Short-beaked Echidna
Encyclopedia
The short-beaked echidna (Tachyglossus aculeatus), also known as the spiny anteater because of its diet of ant
s and termites, is one of four living species of echidna
and the only member of the genus Tachyglossus. The short-beaked echidna is covered in fur and spines, and has a distinctive snout and a specialized tongue, which it uses to catch its prey at a great speed. Like the other extant monotreme
s, the short-beaked echidna lays eggs
; the monotremes are the only group of mammal
s to do so.
This echidna has extremely strong front limbs and claws due to its mechanical advantage
, which allows it to burrow quickly with great power. As it needs to be able to survive underground, it has a great tolerance to high levels of carbon dioxide and a lack of oxygen. It has no weapons or fighting ability, and repels predators by curling into a ball and deterring opponent with its spines. The echidna lacks the ability to sweat and cannot deal with heat well, so it tends to avoid daytime activity in hot weather; it can swim if needed. The snout has mechanical and electroreceptors that help it to detect what is around it, and it also has the ability to reason.
During the winter, it goes into deep torpor and hibernation to save energy and reduce metabolism, before emerging, as the temperature increases, to breed. Female echidnas only lay one egg a year, and the mating period is the only time the otherwise solitary animals meet one another; the male has no further contact with the female after mating. After the young are born, they are only the size of a grape, but grow rapidly on the mothers' milk, which is very rich in nutrients. After a period, they are too large and spiky to stay in the pouch, and after around six months they leave the burrow and have no more contact with their mothers.
The species is found throughout Australia
, where it is the most widespread native mammal, and in coastal and highland regions of southwestern New Guinea
, where it is known as the mungwe in the Daribi
and Chimbu
languages. It is not threatened with extinction, but human activities, such as hunting, habitat destruction, and the introduction
of foreign predatory species and parasites, have reduced the distribution of the short-beaked echidna in Australia. Attempts to breed the echidna in captivity have not been successful to date, with none reaching maturity. However, as the echidna can survive merely by foraging dead logs for ants and termites, it can survive in environments with restricted resources.
in 1792. He named the species
Myrmecophaga aculeata, thinking it might be related to the South American anteater
. Since Shaw first described the species, its name has undergone four revisions: from M. aculeata to Ornithorhynchus hystrix, Echidna hystrix, Echidna aculeata and finally, Tachyglossus aculeatus. The name Tachyglossus means "quick tongue", in reference to the speed with which the echidna uses its tongue to catch ants and termites, and aculeatus means "spiny" or "equipped with spines".
The short-beaked echidna is the only member of its genus
, sharing the family Tachyglossidae
with the extant species of the genus Zaglossus that occur in New Guinea. Zaglossus species, which include the western long-beaked
, Sir David's long-beaked
and eastern long-beaked echidnas
, are all significantly larger than T. aculeatus, and their diets consist mostly of worms and grubs rather than ants and termites. Species of the Tachyglossidae are egg-laying mammals; together with the related family Ornithorhynchidae
, they are the only extant monotreme
s in the world.
The five subspecies of the short-beaked echidna are each found in different geographical locations. The subspecies also differ from one another in their hairiness, spine length and width, and the size of the grooming claws on their hind feet.
The earliest fossils of the short-beaked echidna date back around 15 million years ago to the Pleistocene
era, and the oldest specimens were found in caves in South Australia
, often with fossils of the long-beaked echidna from the same period. The ancient short-beaked echidnas are considered to be identical to their contemporary descendants apart from the fact that the ancestors are around 10% smaller. This "post-Pleistocene dwarfing" affects many Australian mammals. Part of the last radiation of monotreme mammals, echidnas are believed to have evolutionally diverged from the platypus around 65 million years ago, between the Cretacious and Tertiary periods. However, the echidna's pre-Pleistocene heritage has not been traced yet, and the lack of teeth on the fossils found thus far have made it impossible to use dental evidence.
The short-beaked echidna was commonly called the spiny anteater in older books, though this term has fallen out of fashion since the echidna bears no relation to the true anteaters. It has a variety of names in the indigenous languages of the regions where it is found. The Noongar people
from southwestern Western Australia
call it the nyingarn. In Central Australia
southwest of Alice Springs, the Pitjantjatjara term is tjilkamata or tjirili, from the word tjiri for spike of porcupine grass (Triodia irritans
). The word can also mean slowpoke. In central Cape York Peninsula
, it is called (minha) kekoywa in Pakanh, where minha is a qualifier meaning 'meat' or 'animal', (inh-)ekorak in Uw Oykangand and (inh-)egorag in Uw Olkola, where inh- is a qualifier meaning 'meat' or 'animal'.
In the highland regions of southwestern New Guinea
, it is known as the mungwe in the Daribi
and Chimbu
languages.
. Insulation is provided by fur
between the spines, which ranges in colour from honey to a dark reddish-brown and even black; the underside and short tail are also covered in fur. Colouration of the fur and spines varies with geographic location. The echidna's fur may be infested with what is said to be the world's largest flea
, Bradiopsylla echidnae
, which is about 4 mm (0.15748031496063 in) long.
The limbs of the short-beaked echidna are adapted for rapid digging: they are short and have strong claw
s. These strong and stout limbs allow the it to tear apart large logs and move paving stones, and one has been recorded moving a 13.5 kilograms (29.8 lb) stone; there has also been a report of a captive echidna moving a refrigerator in the home of a scientist around the room. The power of the limbs are based on strong musculature, particularly around the shoulder and torso area. The mechanical advantage
of its arm is greater than that of humans, as its biceps connect the shoulder to forearm at a point further down than for humans, and the chunky humerus
allows for larger areas for more muscle to form.
The claws on the hind feet are elongated and curve backward to enable cleaning and grooming between the spines. Like the Platypus, the Echidna has a low body temperature—between 30 and 32 °C (86 and 89.6 °F)—but, unlike the Platypus, which shows no evidence of torpor
or hibernation, the body temperature of the Echidna may fall as low as 5 °C (41 °F). The Echidna does not pant or sweat and normally seeks shelter in hot conditions. Despite the inability to sweat, echidnas still lose water as they exhale. The snout is believed to be crucial in restricting this loss to sustainable levels, through a bony labyrinth that has a refrigerator effect
and helps to condense water vapour in the breath. The echidna does not have highly concentrated urine, and around half of the estimated daily water loss of 120 grams (4.2 oz) occurs in this manner, while most of the rest is through the skin and respiratory system. Most of this is replenished by its substantial eating of termites—one laboratory study reported it would ingest around 147 grams (5.2 oz) a day, most of which was water. This can be supplemented by drinking water if available, or licking morning dew from flora.
In autumn and winter the echidna shows periods of torpor or deep hibernation
. Because of the low body temperature, it becomes sluggish in very hot and very cold weather.
Like all monotremes, it has one orifice
, known as the cloaca
, for the passage of faeces
, urine
and reproductive products. The male has internal testes, no external scrotum
and a highly unusual penis with four knobs on the tip. The gestating
female develops a pouch on its underside, where it raises its young.
The musculature
of the short-beaked echidna has a number of unusual aspects. The panniculus carnosus
is an enormous muscle, just beneath the skin, covers the entire body. By contraction of various parts of the panniculus carnosus, the short-beaked echidna can change shape, the most characteristic shape change being achieved by rolling itself into a ball when threatened, so protecting its belly and presenting a defensive array of sharp spines. It has one of the shortest spinal cord
s of any mammal, extending only as far as the thorax
. Whereas the human spinal cord ends at the first or second lumbar vertebra, for the echidna it occurs at the seventh thoracic vertebra. The shorter spinal cord is thought to allow it the flexibility to wrap into a ball.
The musculature of the face, jaw and tongue is specialised to allow the echidna to feed. The tongue is the animal's sole means of catching prey, and can protrude up to 180 mm (7 in) outside the snout. The snout's shape, resembling a double wedge, gives it a significant mechanical advantage
in generating a large moment, and therefore makes it efficient for digging to reach prey or to build a shelter. The tongue is sticky because of the presence of glycoprotein
-rich mucous, which both lubricates movement in and out of the snout and helps to catch ants and termites, which adhere to it. Protrusion of the tongue is achieved by contracting circular muscles that change the shape of the tongue and force it forwards and contracting two genioglossal muscles attached to the caudal end of the tongue and to the mandible
. The protruded tongue is stiffened by the rapid flow of blood, allowing it to penetrate wood and soil. Retraction requires the contraction of two internal longitudinal muscles, known as the sternoglossi. When the tongue is retracted, the prey is caught on backward-facing keratin
ous "teeth", located along the roof of the buccal cavity, allowing the animal both to capture and grind food. The tongue moves with great speed, and has been measured to move in and out of the snout 100 times a minute. This is partly achieved through the elasticity of the tongue and the conversion of elastic potential energy into kinetic energy
. The tongue is very flexible, particularly at the end, allowing it to bend in U-turns and catch insects attempting to flee in their twisty nests or mounds. The tongue also has an ability to avoid picking up splinters while foraging in logs; the reason for this ability is unknown. It can eat quickly; a specimen of around 3 kilograms (6.6 lb) can ingest 200 grams (7.1 oz) of termites in ten minutes.
The echidna has a stomach that is quite apart from other mammals. It is devoid of secretory glands and has cornified stratified epithelium, which resembles horny skin. Unlike other mammals, which typically have highly acidic stomachs, the Echidna has low levels of acidity, almost neutral with pH
in the 6.2–7.4 range. The stomach is elastic and the gastric peristalsis grinds dirt particulates and shredded insects together. The digestion occurs in the small intestine, which is around 3.4 metres (11.2 ft) in length. The insect exoskeletons and dirt are not digested and ejected in the waste.
Numerous physiological adaptations aid the lifestyle of the short-beaked echidna. Because the animal burrows, it must tolerate very high levels of carbon dioxide
in inspired air, and will voluntarily remain in situations where carbon dioxide concentrations are high. It can dig up to a metre into the ground to retrieve ants or evade predators, and can survive with low oxygen when the area is engulfed by bushfires. The echidna can also dive underwater, an ability that can help it to survive sudden floods. During these situations, the heart rate drops to around 12 beats per minute, around one fifth of the rate at rest. This process is believed to save oxygen for the heart and brain, which are the most sensitive to such a shortage, and laboratory testing has revealed its cardiovascular system is similar to that of the seal.
The echidna's optical system is an uncommon hybrid of both mammalian and reptilian characteristics. The cartilaginous layer beneath the scleral layer of the eyeball is similar to that of reptiles and avians. The small cornea
's surface is keratinised and hardened, possibly an evolution to protect it from chemicals secreted by preyed insects or self-impalement when it rolls itself up, something that has been observed. The echidna has the flattest lens of any animal, giving it the longest focal length
. This similarity to primates and humans allows it to see distant objects clearly. Unlike placental mammals, including humans, the echidna does not have a ciliary muscle to distort the geometry of the lens and thereby change the focal length and allow objects at different distances to be viewed clearly; the whole eye is believed to distort so the distance between the lens and screen instead changes to allow focusing. The visual ability of an echidna is not great, and it is not known whether it can perceive colour; however, it can distinguish between black and white, and horizontal and vertical stripes. Eyesight is not a crucial factor in the animal's ability to survive, as blind echidnas are able to live healthily.
Its ear is sensitive to low-frequency
sound, which may be ideal for detecting sounds emitted by termites and ants underground. The pinnae are obscured and covered by hair, so opponents can not grab them in an attack, and prey or foreign material cannot enter, although tick
s are known to reside there. The ear has a macula
which is very large compared to other animals. It is used as a gravity sensor to orient the echidna. The large size is speculated to be due to importance of burrowing downwards for an echidna.
The leathery snout is keratinised and covered in mechano- and thermoreceptors, which provide information about the surrounding environment. These nerves protrude through microscopic holes at the end of the snout. It also has mucous glands on the end of the snout that act as electroreceptors. It can detect electric field
s of 1.8 mV/cm—1,000 times more sensitive than humans—and dig up buried batteries. Echidnaa have a series of push rods protruding from their snouts. These are columns of flattened, spinous cells, with roughly an average diameter of 50 micrometres and a length of 300 micrometres. The number of push rods per square millimetre of skin is estimated to be 30 to 40. Longitudinal waves are believed to be picked up and transmitted through the rods, acting as mechanical sensors, to allow prey detection.
The short-beaked echidna has a well-developed olfactory system
, which may be used to detect mates and prey. It has a highly sensitive optic nerve
, and has been shown to have visual discrimination and spatial memory
comparable to those of a rat
. The brain
and central nervous system
have been extensively studied for evolutionary comparison with placental mammals, particularly with its fellow monotreme, the platypus. The average brain volume is 25 mL, similar to a cat of approximately the same size; while the platypus has a largely lissencephalic and smooth brain, the echidna has a heavily folded and fissured, gyrencephalic brain similar to humans, which is seen as a sign of a highly neurologically advanced animal. The cerebral cortex is thinner, the brain cells larger and more densely packed and organised in the echidna than the platypus, suggesting evolutionary divergence must have occurred long ago. Almost half of the sensory area in the brain is devoted to the snout and tongue, and the part devoted to smell is relatively large compared to other animals.
The short-beaked echidna has the largest prefrontal cortex
relative to body size of any mammal, taking up 50% of the cerebral cortex in comparison to 29% for humans. This part of the brain in humans is though to be used for planning and analytical behaviour, leading to debate as to whether the echidna has reasoning and strategising ability. Experiments in a simple maze and with a test on whether the animal can open a trap door to access food, and the echidna's ability to remember what it has learnt about the task for over a month, has led scientists to conclude its learning ability is similar to that of a cat or a rat.
The echidna shows rapid eye movement during sleep, usually around its thermoneutral temperature of 25°C, and this effect is suppressed at other temperatures. Its brain has been shown to contain a claustrum
similar to that of placental mammals, so linking this structure to their common ancestor
.
Short-beaked echidnas are typically active in the daytime, though they are ill-equipped to deal with heat because they have no sweat gland
s and do not pant. Therefore, in warm weather, they change their patterns of activity, becoming crepuscular
or nocturnal. Body temperatures above 34 °C (93.2 °F) are believed to be fatal, and in addition to avoiding heat, the animal adjusts its circulation to maintain a sustainable temperature by moving blood to and from the skin to increase or lower heat loss. In areas where water is present, they can also swim to keep their body temperatures low. The "thermoneutral zone" for the environment is around 25 °C (77 °F), at which point metabolism needed to maintain body temperature is minimized. Echidnas can tolerate cold temperatures, and they hibernate during the winter both in cold regions and in regions with a more temperate climate. The echidna is endothermic, and can maintain body temperatures of around 32°C. It can also reduce its metabolism and heart rate and body temperature. In addition to brief and light bouts of torpor throughout the year, the echidna enters periods during winter when it hibernates. During periods of hibernation, the body temperature drops to as low as 4 °C (39.2 °F). The heart rate falls to 4–7 beats per minute—down from 50–68 at rest&mdash, and the echidna can breathe as infrequently as once every three minutes, 80 to 90% slower than when it is active. Metabolism can drop to one-eighth of the normal rate. Echidnas begin to prepare for the hibernation phase of the year between February and April, when they reduce their consumption and enter brief periods of torpor. Males begin hibernating first, while females that have reproduced start later. During the period of hibernation, the animals average 13 separate bouts of torpor, which are broken up by periods of arousal lasting 1.2 days on average. These interruptions tend to coincide with warmer periods. Males end their hibernation period in mid-June, while reproductive females return to full activity in July and August; nonreproductive females and immature echidnas may not end hibernation until two months later. During euthermia, the body temperature can vary by 4 °C (39.2 °F) per day. The metabolic rate is around 30% of that of placental mammals, making it the lowest energy-consuming mammal. This figure is similar to that of other animals that eat ants and termites; burrowing animals also tend to have low metabolism generally.
Questions have arisen as to why echidnas hibernate, as it is seemingly unnecessary for survival; they begin their hibernation period while the weather is still warm, and food is generally always plentiful. One explanation of this phenomenon is echidnas want to be cautious with their energy reserves to maximize their foraging productivity. Another hypothesis is they are descended from ectothermic ancestors, but have taken to periodic endothermy for reproductive reasons, so the young can develop more quickly. Supporters of this theory argue that males hibernate earlier than females because they finish their contribution to reproduction first, and they awake earlier to undergo spermatogenosis in preparation for mating, while females and young lag in their annual cycle. During the hibernation period, the animals stay in entirely covered shelter.
Short-beaked echidnas can live anywhere that has a good supply of food. They locate food by smell, using sensors in the tips of their snouts, and regularly feast on ants and termites. This view is based on the echidna's method of shuffling around seemingly arbitrarily, and using its snout in a probing manner. A study of Echidnas in New England has shown that they tend to dig up scarab beetle
larvae in spring when the prey are active, but eschew this prey when it is inactive; this has been used to support the conjecture that Echidnas detect their prey using hearing. Vision is not believed to be significant in hunting, as blind animals have been observed to survive in the wild.
Echidnas use their strong claws to pull apart nests and rotting logs to gain access to their prey. They are selective of what types of ants and termites they target because some of their would-be prey secrete repulsive liquids. They also have a preference for the eggs, pupae and winged phases of the insects. Echidnas hunt most vigorously towards the end of winter and early in spring, when their fat reserves have been depleted after hibernation and/or nursing. At this time of the year, ants have high body fat, and the echidna targets their mounds. The animal also hunts beetles and earthworms, providing they are small enough to fit in a 5 mm gap. The proportion of ants and termites in their diet depends on the availability of prey, and termites make up a larger part in drier areas where they are more plentiful. However, termites are preferred, if available, as their bodies contain a smaller proportion of indigestible exoskeleton. Termites from the Rhinotermitidae
family, however, are avoided due to their chemical defenses. Scarab beetle larvae are also a large part of the diet when and where available. In a study conducted in New England
in New South Wales
, 37% of the food intake consisted of beetle larvae, although the echidna had to squash the prey in its snout as it ingested it, due to size.
Echidnas are powerful diggers, using their clawed front paws to dig out prey and create burrows for shelter. They may rapidly dig themselves into the ground if they cannot find cover when in danger. They bend their belly together to shield the soft, unprotected part, and can also urinate, giving off a pungent liquid, in an attempt to deter attackers. Males also have single small spurs on each rear leg that is believed to a defensive weapon that has since been lost to the evolutionary process. Echidnas typically try to avoid confrontation with predators due to their lack of anatomical weaponry. Instead, they use the colour of their spines, which is similar to the vegetation of the dry Australian environment, to avoid detection. They have good hearing and tend to become stationary if sound is detected.
In Australia, they are most common in forested areas where there are abundant, termite-filled, fallen logs. In agricultural areas, they are most likely to be found in uncleared scrub; they may be found in grassland, arid areas, and in the outer suburbs of the capital cities. Little is known about their distribution in New Guinea. They have been found in southern New Guinea between Merauke in the west and the Kelp Welsh River, east of Port Moresby
, in the east, where they may be found in open woodland.
Echidnas have the ability to swim, and have been seen cooling off near dams during high temperatures. They have also been seen crossing streams and swimming for brief periods in seas off Kangaroo Island. They swim with only the snout above water, using it as a snorkel.
The solitary short-beaked echidna looks for a mate between May and September; the precise timing of the mating season varies with geographic location. In the months before the mating season, the size of the male's testes increases by a factor of three or more before spermatogenesis occurs. Both males and females give off a strong, musky odour during the mating season, by turning their cloacas inside out and wiping them on the ground, secreting a glossly liquid believed to be an aphrodisiac. During courtship—observed for the first time in 1989—males locate and pursue females. Trains of up to ten males—often with the youngest and smallest male at the end of the queue—may follow a single female in a courtship ritual that may last for up to four weeks; the duration of the courtship period varies with location. During this time, they forage for food together, and the train often changes composition, as some males leave and other join the pursuit. In cooler parts of their range, such as Tasmania, females may mate within a few hours of arousal from hibernation.
Before mating, the male smells the female, paying particular attention to the cloaca
. This process can take a few hours, and the female can reject the suitor by rolling herself into a ball. After prodding and sniffing her back, the male is often observed to roll the female onto her side and then assume a similar position himself so that the two animals are abdomen to abdomen, having dug a small crater to lie in. They can lie with heads facing one another, or head to rear. If more than one male is in the vicinity, there may be fighting over the female. Each side of the bilaterally symmetrical, rosette-like, four-headed penis [similar to that of reptiles and 7 centimetres (2.8 in) in length] is used alternately, with the other half being shut down between ejaculations. Sperm bundles of around 100 each appear to confer increased sperm motility, which may provide the potential for sperm competition between males. This process takes between a half an hour and three hours. Each mating results in the production of a single egg, and females are known to mate only once during the breeding season; each mating is successful.
Fertilisation occurs in the oviduct
. Gestation
takes between 21 and 28 days after copulation, during which time the female constructs a nursery burrow. Following the gestation period, a single, rubbery-skinned egg between 13 and 17 mm (0.511811023622047 and 0.669291338582677 ) in diameter and 1.5 and 2 g (0.0529109431576679 and 0.0705479242102239 oz) in weight is laid from her cloaca directly into a small, backward-facing pouch that has developed on her abdomen. The egg is ovoid, leathery, soft and cream-coloured. Between laying and hatching, some females continue to forage for food, while others dig burrows and rest there until hatching. Ten days after it is laid, the egg hatches within the pouch. The embryo develops an "egg tooth" during incubation, which it uses to tear open the egg; the tooth disappears soon after hatching.
Hatchlings are about 1.5 centimetre (0.590551181102362 in) long and weigh between 0.3 and 0.4 g (0.0105821886315336 and 0.0141095848420448 oz). After hatching, young echidnas are known as "puggles". Although newborns are still semitranslucent and still surrounded by the remains of the egg yolk, and the eyes are still barely developed, they already have well-defined front limbs and digits that allow them to climb on their mothers' bodies. Hatchlings attach themselves to their mothers' milk areolae, specialised patches on the skin that secrete milk—monotremes lack nipples—through approximately 100–150 pores. The puggles were thought to have imbibed the milk by licking the mother's skin, but this has been superseded by a belief they feed by sucking the areolae.
They have been observed ingesting large amounts during each feeding period, and mothers may leave them unattended in the burrow for between five and 10 days to find food. Studies of captives have shown they can ingest milk once every two or three days and then increase their mass by 20% in one milk-drinking session lasting between one and two hours. Around 40% of the milk weight is converted into body mass, and as such, a high proportion of milk is converted into growth; a correlation with the growth of the puggle and its mother's size has been observed. By the time the puggle is around 200 grams (7.1 oz), it is left in the burrow while the mother forages for food, and it reaches around 400 grams (14.1 oz) after around two months. Juveniles are eventually ejected from the pouch at around two to three months of age, because of the continuing growth in the length of their spines. During this period, the young are left in covered burrows while the mothers forage, and the young are often preyed upon. Suckling gradually decreases until juveniles are weaned at about six months of age. The duration of lactation is about 200 days, and the young leave the burrow after 180 to 205 days, usually in January or February, at which time they are around 800 and 1300 g (28.2 and 45.9 oz). There is no contact between the mother and young after this point.
The composition of the milk secreted by the mother changes over time. At the moment of birth, the solution is dilute and contains 1.25% fat, 7.85% protein, and 2.85% carbohydrates and minerals. Mature milk has much more concentrated nutrients, with 31.0, 12.4 and 2.8% of the aforementioned nutrients, respectively. Near weaning, the protein level continues to increase; this is conjectured to be due to the need for keratin synthesis for hair and spines, to provide defences against the cold weather and predators.
The principal carbohydrate components of the milk are fucosyllactose and saialyllactose; it has a high iron content, which gives it a pink colour. The high iron content and low levels of free lactose contrasts with other eutherian mammals. Lactose production is believed to proceed along the same lines as in the platypus.
The age of sexual maturity is uncertain, but may be four to five years. A 12-year field study, published in 2003, found the short-beaked echidna reaches sexual maturity between five and 12 years of age, and that the frequency of reproduction varies from once every two years to once every six years. The short-beaked echidna can live as long as 45 years in the wild, and the longest-lived echidna in captivity reached 49 years of age in a zoo in Philadelphia in the US. Echidnas contrast to other mammals in that their rates of reproduction and metabolism are lower, and they live longer, as though in slow motion, something caused, at least in part, by their low body temperature, which rarely exceeds 33°C, even when they are not hibernating.
Like its fellow monotreme the platypus, the short-beaked echidna has a system of multiple sex chromosomes
, in which males have four Y chromosome
s and five X chromosome
s. Male individuals appear to be X1Y1X2Y2X3Y3X4Y4X5 (figure), while females are X1X1X2X2X3X3X4X4X5X5. Weak identity between chromosomes results in meiotic pairing
that yields only two possible genotype
s of sperm, X1X2X3X4X5 or Y1Y2Y3Y4, thus preserving this complex system.
The short-beaked echidna is common throughout most of temperate Australia and lowland New Guinea, and is not listed as endangered. In Australia, it remains widespread across a wide range of conditions, including urban outskirts, coastal forests and dry inland areas, and is especially widespread in Tasmania and on Kangaroo Island
.
The most common threats to the animal in Australia are motor vehicles and habitat destruction, which have led to localized extinctions. In Australia, the number of short-beaked echidnas has been less affected by land clearance than have some other species, since they do not require a specialized habitat beyond a good supply of ants and termites. As a result, they can survive in cleared land if the cut-down wood is left in the area, as the logs can be used as shelter and a source of insects. However, areas where the land has been completely cleared for single crops that can be mechanically harvested, such as wheatfields, have seen extinctions. Over a decade-long period, around one-third of Echidna deaths reported to wildlife authorities in Victoria were due to motor vehicles, and the majority of wounded animals handed in were traffic accident victims. Studies have shown they often choose to traverse drainage culverts under roads, so this is seen as a viable means of reducing deaths on busy roads in rural areas or national parks where the animals are more common.
Despite their spines, they are preyed on by birds, the Tasmanian devil
, dingoes, snakes, lizards, goannas, cats and foxes, although almost all victims are young. Goannas are known for their digging abilities and strong sense of smell, and are believed to be have been the main predators of the echidna before the introduction of most of the other predators by European settlers. Dingoes are known to kill echidnas by rolling them over onto their backs and attacking their underbellies. A tracking study of a small number of echidnas on Kangaroo Island concluded goannas and cats were the main predators, although foxes—absent in Kangaroo Island—would be expected to be a major threat, also, as the echidna density in Tasmania—which is free from foxes—is higher in other parts of Australia.
They were eaten by indigenous Australians
and the early European settlers of Australia. In contrast, hunting and eating of the echidna in New Guinea has increased over time and caused a decline in the population and distribution areas; it is now believed to have disappeared from highland areas. The killing of echidnas was a taboo in traditional culture, but since the tribespeople have become increasingly Christianised by western missionaries, hunting has increased, and the animals have been more easily tracked down due to the use of dogs.
Infection with the introduced parasite Spirometra erinaceieuropaei
is considered fatal for the echidna. This is a waterborne infection contracted through sharing drinking areas with infected dogs, foxes, cats and dingos, which do not die from the parasite. The infection is seen as being more dangerous in drier areas, where more animals are sharing fewer bodies of water, increasing the chance of transmission. The Wildlife Preservation Society of Queensland runs an Australia-wide survey, called Echidna Watch, to monitor the species in Australia. Echidnas are also known to be affected by tapeworms, protozoans and herpes-like viral infections, but there is little knowledge of how infections affect the health of the animals or the populations.
Although it considered easy to keep echidnas healthy in captivity, breeding is difficult, partly due to the relatively infrequent cycle. In 2009, Perth Zoo
managed to breed some captive short-beaked echidnas. Until 2006, only five zoos have managed to breed a captive short-beaked echidna, but no captive-bred young have survived to maturity. Of these five institutions, only one in Australia—Sydney
's Taronga Zoo
—managed to breed echidnas, in 1977. The other four cases occurred in the Northern Hemisphere, two in the United States and the others in western Europe. In these cases, breeding occurred six months out of phase compared to Australia, after the animals had adapted to Northern Hemisphere seasons. The failure of captive breeding programs has conservation implications for the endangered species of echidna from the genus Zaglossus, and to a lesser extent for the short-beaked echidna.
culture of indigenous Australians, including their visual arts
and stories. The species was a totem for some groups, including the Noongar people
from Western Australia. Many groups have myths about the animal; one myth explains it was created when a group of hungry young men went hunting at night and stumbled across a wombat
. They threw spears at the wombat, but lost sight of it in the darkness. The wombat adapted the spears for its own defence and turned into an echidna. Another story tells of a greedy man who kept food from his tribe; warriors speared him and he crawled away into the bushes, where he turned into an echidna, the spears becoming his spines.
The short-beaked echidna is an iconic animal in contemporary Australia, notably appearing on the Australian five-cent coin (the smallest denomination), and on a AU
$200 commemorative coin released in 1992. The short-beaked echidna has been included in several postal issues: it was one of four native species to appear on Australian postage stamps in 1974, when it was on the 25-cent stamp; it appeared on a 37-cent stamp in 1987, and in 1992 it was on the 35-cent stamp. The anthropomorphic echidna Millie was a mascot for the 2000 Summer Olympics. Knuckles the Echidna
, from the Sonic the Hedgehog
series is also based on the short-beaked echidna.
Ant
Ants are social insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the mid-Cretaceous period between 110 and 130 million years ago and diversified after the rise of flowering plants. More than...
s and termites, is one of four living species of echidna
Echidna
Echidnas , also known as spiny anteaters, belong to the family Tachyglossidae in the monotreme order of egg-laying mammals. There are four extant species, which, together with the platypus, are the only surviving members of that order and are the only extant mammals that lay eggs...
and the only member of the genus Tachyglossus. The short-beaked echidna is covered in fur and spines, and has a distinctive snout and a specialized tongue, which it uses to catch its prey at a great speed. Like the other extant monotreme
Monotreme
Monotremes are mammals that lay eggs instead of giving birth to live young like marsupials and placental mammals...
s, the short-beaked echidna lays eggs
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
; the monotremes are the only group of mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s to do so.
This echidna has extremely strong front limbs and claws due to its mechanical advantage
Mechanical advantage
Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. Ideally, the device preserves the input power and simply trades off forces against movement to obtain a desired amplification in the output force...
, which allows it to burrow quickly with great power. As it needs to be able to survive underground, it has a great tolerance to high levels of carbon dioxide and a lack of oxygen. It has no weapons or fighting ability, and repels predators by curling into a ball and deterring opponent with its spines. The echidna lacks the ability to sweat and cannot deal with heat well, so it tends to avoid daytime activity in hot weather; it can swim if needed. The snout has mechanical and electroreceptors that help it to detect what is around it, and it also has the ability to reason.
During the winter, it goes into deep torpor and hibernation to save energy and reduce metabolism, before emerging, as the temperature increases, to breed. Female echidnas only lay one egg a year, and the mating period is the only time the otherwise solitary animals meet one another; the male has no further contact with the female after mating. After the young are born, they are only the size of a grape, but grow rapidly on the mothers' milk, which is very rich in nutrients. After a period, they are too large and spiky to stay in the pouch, and after around six months they leave the burrow and have no more contact with their mothers.
The species is found throughout Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, where it is the most widespread native mammal, and in coastal and highland regions of southwestern New Guinea
New Guinea
New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...
, where it is known as the mungwe in the Daribi
Dadibi language
Dadibi is a language of Papua New Guinea....
and Chimbu
Kuman language (New Guinea)
Kuman is a language of Simbu Province, Papua New Guinea. , it was spoken by about 80,000 people, 10,000 of which were monolinguals. In 2000 the number of speakers increased to 115,000.-References:...
languages. It is not threatened with extinction, but human activities, such as hunting, habitat destruction, and the introduction
Invasive species in Australia
Invasive species are a serious threat to the native biodiversity of Australia and are an ongoing cost to Australian agriculture.Management and the prevention of the introduction of new invasive species are key environmental and agricultural policy issues for the Australian federal and state...
of foreign predatory species and parasites, have reduced the distribution of the short-beaked echidna in Australia. Attempts to breed the echidna in captivity have not been successful to date, with none reaching maturity. However, as the echidna can survive merely by foraging dead logs for ants and termites, it can survive in environments with restricted resources.
Taxonomy and naming
The short-beaked echidna was first described by George ShawGeorge Shaw
George Shaw was an English botanist and zoologist.Shaw was born at Bierton, Buckinghamshire and was educated at Magdalen Hall, Oxford, receiving his M.A. in 1772. He took up the profession of medical practitioner. In 1786 he became the assistant lecturer in botany at Oxford University...
in 1792. He named the species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
Myrmecophaga aculeata, thinking it might be related to the South American anteater
Anteater
Anteaters, also known as antbear, are the four mammal species of the suborder Vermilingua commonly known for eating ants and termites. Together with the sloths, they compose the order Pilosa...
. Since Shaw first described the species, its name has undergone four revisions: from M. aculeata to Ornithorhynchus hystrix, Echidna hystrix, Echidna aculeata and finally, Tachyglossus aculeatus. The name Tachyglossus means "quick tongue", in reference to the speed with which the echidna uses its tongue to catch ants and termites, and aculeatus means "spiny" or "equipped with spines".
The short-beaked echidna is the only member of its genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
, sharing the family Tachyglossidae
Echidna
Echidnas , also known as spiny anteaters, belong to the family Tachyglossidae in the monotreme order of egg-laying mammals. There are four extant species, which, together with the platypus, are the only surviving members of that order and are the only extant mammals that lay eggs...
with the extant species of the genus Zaglossus that occur in New Guinea. Zaglossus species, which include the western long-beaked
Western Long-beaked Echidna
The western long-beaked echidna is one of the four extant echidnas and one of three species of Zaglossus that occur in New Guinea. As Tachyglossus bruijni, this is the type species of Zaglossus....
, Sir David's long-beaked
Sir David's Long-beaked Echidna
Sir David's long-beaked echidna , also known as Attenborough's long-beaked echidna or the Cyclops long-beaked echidna, is one of three species from the genus Zaglossus to occur in New Guinea. It is named in honour of Sir David Attenborough, the eminent naturalist...
and eastern long-beaked echidnas
Eastern Long-beaked Echidna
The eastern long-beaked echidna , also known as Barton's long-beaked echidna, is one of three species from the genus Zaglossus to occur in New Guinea...
, are all significantly larger than T. aculeatus, and their diets consist mostly of worms and grubs rather than ants and termites. Species of the Tachyglossidae are egg-laying mammals; together with the related family Ornithorhynchidae
Platypus
The platypus is a semi-aquatic mammal endemic to eastern Australia, including Tasmania. Together with the four species of echidna, it is one of the five extant species of monotremes, the only mammals that lay eggs instead of giving birth to live young...
, they are the only extant monotreme
Monotreme
Monotremes are mammals that lay eggs instead of giving birth to live young like marsupials and placental mammals...
s in the world.
The five subspecies of the short-beaked echidna are each found in different geographical locations. The subspecies also differ from one another in their hairiness, spine length and width, and the size of the grooming claws on their hind feet.
- T. a. acanthion is found in Northern TerritoryNorthern TerritoryThe Northern Territory is a federal territory of Australia, occupying much of the centre of the mainland continent, as well as the central northern regions...
and Western AustraliaWestern AustraliaWestern Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
; - T. a. aculeatus is found in QueenslandQueenslandQueensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
, New South WalesNew South WalesNew South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
, South AustraliaSouth AustraliaSouth Australia is a state of Australia in the southern central part of the country. It covers some of the most arid parts of the continent; with a total land area of , it is the fourth largest of Australia's six states and two territories.South Australia shares borders with all of the mainland...
and VictoriaVictoria (Australia)Victoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales, South Australia, and Tasmania on Boundary Islet to the north, west and south respectively....
; - T. a. lawesii is found in coastal regions and the highlands of New Guinea, and possibly in the rainforests of Northeast Queensland;
- T. a. multiaculeatus is found on Kangaroo IslandKangaroo IslandKangaroo Island is Australia's third-largest island after Tasmania and Melville Island. It is southwest of Adelaide at the entrance of Gulf St Vincent. Its closest point to the mainland is off Cape Jervis, on the tip of the Fleurieu Peninsula in the state of South Australia. The island is long...
; - T. a. setosus is found on TasmaniaTasmaniaTasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...
and some islands in Bass StraitBass StraitBass Strait is a sea strait separating Tasmania from the south of the Australian mainland, specifically the state of Victoria.-Extent:The International Hydrographic Organization defines the limits of the Bass Strait as follows:...
.
The earliest fossils of the short-beaked echidna date back around 15 million years ago to the Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
era, and the oldest specimens were found in caves in South Australia
South Australia
South Australia is a state of Australia in the southern central part of the country. It covers some of the most arid parts of the continent; with a total land area of , it is the fourth largest of Australia's six states and two territories.South Australia shares borders with all of the mainland...
, often with fossils of the long-beaked echidna from the same period. The ancient short-beaked echidnas are considered to be identical to their contemporary descendants apart from the fact that the ancestors are around 10% smaller. This "post-Pleistocene dwarfing" affects many Australian mammals. Part of the last radiation of monotreme mammals, echidnas are believed to have evolutionally diverged from the platypus around 65 million years ago, between the Cretacious and Tertiary periods. However, the echidna's pre-Pleistocene heritage has not been traced yet, and the lack of teeth on the fossils found thus far have made it impossible to use dental evidence.
The short-beaked echidna was commonly called the spiny anteater in older books, though this term has fallen out of fashion since the echidna bears no relation to the true anteaters. It has a variety of names in the indigenous languages of the regions where it is found. The Noongar people
Noongar
The Noongar are an indigenous Australian people who live in the south-west corner of Western Australia from Geraldton on the west coast to Esperance on the south coast...
from southwestern Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
call it the nyingarn. In Central Australia
Central Australia
Central Australia/Alice Springs Region is one of the five regions in the Northern Territory. The term Central Australia is used to describe an area centred on Alice Springs in Australia. It is sometimes referred to as Centralia; likewise the people of the area are sometimes called Centralians...
southwest of Alice Springs, the Pitjantjatjara term is tjilkamata or tjirili, from the word tjiri for spike of porcupine grass (Triodia irritans
Triodia (plant genus)
Triodia is a large genus of hummock-forming grass endemic to Australia; they are commonly known as spinifex, although they are not a part of the coastal genus Spinifex. There are currently 64 recognised species...
). The word can also mean slowpoke. In central Cape York Peninsula
Cape York Peninsula
Cape York Peninsula is a large remote peninsula located in Far North Queensland at the tip of the state of Queensland, Australia, the largest unspoilt wilderness in northern Australia and one of the last remaining wilderness areas on Earth...
, it is called (minha) kekoywa in Pakanh, where minha is a qualifier meaning 'meat' or 'animal', (inh-)ekorak in Uw Oykangand and (inh-)egorag in Uw Olkola, where inh- is a qualifier meaning 'meat' or 'animal'.
In the highland regions of southwestern New Guinea
New Guinea
New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...
, it is known as the mungwe in the Daribi
Dadibi language
Dadibi is a language of Papua New Guinea....
and Chimbu
Kuman language (New Guinea)
Kuman is a language of Simbu Province, Papua New Guinea. , it was spoken by about 80,000 people, 10,000 of which were monolinguals. In 2000 the number of speakers increased to 115,000.-References:...
languages.
Description
Short-beaked echidnas are typically 30 to 45 cm (11.8 to 17.7 in) in length, have a 75 millimetres (3 in) snout, and weigh between 2 and 5 kg (4.4 and 11 lb). However, the Tasmanian subspecies, T. a. setosus, is smaller than its Australian mainland counterparts. Because the neck is not externally visible, the head and body appear to merge together. The earholes are on either side of the head, with no external pinnae. The eyes are small, approximately a 9 mm (0.354330708661417 in)-diameter sphere and at the base of the wedge-shaped snout. The nostrils and the mouth are at the distal end of the snout; the mouth of the Short-beaked Echidna cannot open wider than 5 mm (0.196850393700787 in). The body of the Short-beaked Echidna is, with the exception of the underside, face and legs, covered with cream-coloured spines. The spines, which may be up to 50 mm (2 in) long, are modified hairs, mostly made of keratinKeratin
Keratin refers to a family of fibrous structural proteins. Keratin is the key of structural material making up the outer layer of human skin. It is also the key structural component of hair and nails...
. Insulation is provided by fur
Fur
Fur is a synonym for hair, used more in reference to non-human animals, usually mammals; particularly those with extensives body hair coverage. The term is sometimes used to refer to the body hair of an animal as a complete coat, also known as the "pelage". Fur is also used to refer to animal...
between the spines, which ranges in colour from honey to a dark reddish-brown and even black; the underside and short tail are also covered in fur. Colouration of the fur and spines varies with geographic location. The echidna's fur may be infested with what is said to be the world's largest flea
Flea
Flea is the common name for insects of the order Siphonaptera which are wingless insects with mouthparts adapted for piercing skin and sucking blood...
, Bradiopsylla echidnae
Echidna flea
The echidna flea is thought to be the world's largest flea and it parasitises the short-beaked echidna. It reaches 4 millimetres in length.-References:*...
, which is about 4 mm (0.15748031496063 in) long.
The limbs of the short-beaked echidna are adapted for rapid digging: they are short and have strong claw
Claw
A claw is a curved, pointed appendage, found at the end of a toe or finger in most mammals, birds, and some reptiles. However, the word "claw" is also often used in reference to an invertebrate. Somewhat similar fine hooked structures are found in arthropods such as beetles and spiders, at the end...
s. These strong and stout limbs allow the it to tear apart large logs and move paving stones, and one has been recorded moving a 13.5 kilograms (29.8 lb) stone; there has also been a report of a captive echidna moving a refrigerator in the home of a scientist around the room. The power of the limbs are based on strong musculature, particularly around the shoulder and torso area. The mechanical advantage
Mechanical advantage
Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. Ideally, the device preserves the input power and simply trades off forces against movement to obtain a desired amplification in the output force...
of its arm is greater than that of humans, as its biceps connect the shoulder to forearm at a point further down than for humans, and the chunky humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
allows for larger areas for more muscle to form.
The claws on the hind feet are elongated and curve backward to enable cleaning and grooming between the spines. Like the Platypus, the Echidna has a low body temperature—between 30 and 32 °C (86 and 89.6 °F)—but, unlike the Platypus, which shows no evidence of torpor
Torpor
Torpor, sometimes called temporary hibernation is a state of decreased physiological activity in an animal, usually characterized by a reduced body temperature and rate of metabolism. Animals that go through torpor include birds and some mammals such as mice and bats...
or hibernation, the body temperature of the Echidna may fall as low as 5 °C (41 °F). The Echidna does not pant or sweat and normally seeks shelter in hot conditions. Despite the inability to sweat, echidnas still lose water as they exhale. The snout is believed to be crucial in restricting this loss to sustainable levels, through a bony labyrinth that has a refrigerator effect
Thermodynamic cycle
A thermodynamic cycle consists of a series of thermodynamic processes transferring heat and work, while varying pressure, temperature, and other state variables, eventually returning a system to its initial state...
and helps to condense water vapour in the breath. The echidna does not have highly concentrated urine, and around half of the estimated daily water loss of 120 grams (4.2 oz) occurs in this manner, while most of the rest is through the skin and respiratory system. Most of this is replenished by its substantial eating of termites—one laboratory study reported it would ingest around 147 grams (5.2 oz) a day, most of which was water. This can be supplemented by drinking water if available, or licking morning dew from flora.
In autumn and winter the echidna shows periods of torpor or deep hibernation
Hibernation
Hibernation is a state of inactivity and metabolic depression in animals, characterized by lower body temperature, slower breathing, and lower metabolic rate. Hibernating animals conserve food, especially during winter when food supplies are limited, tapping energy reserves, body fat, at a slow rate...
. Because of the low body temperature, it becomes sluggish in very hot and very cold weather.
Like all monotremes, it has one orifice
Body orifice
-External orifices:In a typical mammalian body such as the human body, the external body orifices are:* The nostrils, for breathing and the associated sense of smell.* The eyes, for the sense of sight and crying....
, known as the cloaca
Cloaca
In zoological anatomy, a cloaca is the posterior opening that serves as the only such opening for the intestinal, reproductive, and urinary tracts of certain animal species...
, for the passage of faeces
Feces
Feces, faeces, or fæces is a waste product from an animal's digestive tract expelled through the anus or cloaca during defecation.-Etymology:...
, urine
Urine
Urine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream...
and reproductive products. The male has internal testes, no external scrotum
Scrotum
In some male mammals the scrotum is a dual-chambered protuberance of skin and muscle containing the testicles and divided by a septum. It is an extension of the perineum, and is located between the penis and anus. In humans and some other mammals, the base of the scrotum becomes covered with curly...
and a highly unusual penis with four knobs on the tip. The gestating
Gestation
Gestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals during pregnancy can have one or more gestations at the same time ....
female develops a pouch on its underside, where it raises its young.
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
of the short-beaked echidna has a number of unusual aspects. The panniculus carnosus
Panniculus carnosus
The panniculus carnosus is a part of the subcutaneous tissues in the study of animal anatomy. It is a layer of striated muscle deep to the panniculus adiposus. In humans the platysma muscle of the neck, palmaris brevis in the hand, and the dartos muscle in the scrotum are described as a discrete...
is an enormous muscle, just beneath the skin, covers the entire body. By contraction of various parts of the panniculus carnosus, the short-beaked echidna can change shape, the most characteristic shape change being achieved by rolling itself into a ball when threatened, so protecting its belly and presenting a defensive array of sharp spines. It has one of the shortest spinal cord
Spinal cord
The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain . The brain and spinal cord together make up the central nervous system...
s of any mammal, extending only as far as the thorax
Thorax
The thorax is a division of an animal's body that lies between the head and the abdomen.-In tetrapods:...
. Whereas the human spinal cord ends at the first or second lumbar vertebra, for the echidna it occurs at the seventh thoracic vertebra. The shorter spinal cord is thought to allow it the flexibility to wrap into a ball.
The musculature of the face, jaw and tongue is specialised to allow the echidna to feed. The tongue is the animal's sole means of catching prey, and can protrude up to 180 mm (7 in) outside the snout. The snout's shape, resembling a double wedge, gives it a significant mechanical advantage
Mechanical advantage
Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. Ideally, the device preserves the input power and simply trades off forces against movement to obtain a desired amplification in the output force...
in generating a large moment, and therefore makes it efficient for digging to reach prey or to build a shelter. The tongue is sticky because of the presence of glycoprotein
Glycoprotein
Glycoproteins are proteins that contain oligosaccharide chains covalently attached to polypeptide side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycosylation. In proteins that have segments extending...
-rich mucous, which both lubricates movement in and out of the snout and helps to catch ants and termites, which adhere to it. Protrusion of the tongue is achieved by contracting circular muscles that change the shape of the tongue and force it forwards and contracting two genioglossal muscles attached to the caudal end of the tongue and to the mandible
Mandible
The mandible pronunciation or inferior maxillary bone forms the lower jaw and holds the lower teeth in place...
. The protruded tongue is stiffened by the rapid flow of blood, allowing it to penetrate wood and soil. Retraction requires the contraction of two internal longitudinal muscles, known as the sternoglossi. When the tongue is retracted, the prey is caught on backward-facing keratin
Keratin
Keratin refers to a family of fibrous structural proteins. Keratin is the key of structural material making up the outer layer of human skin. It is also the key structural component of hair and nails...
ous "teeth", located along the roof of the buccal cavity, allowing the animal both to capture and grind food. The tongue moves with great speed, and has been measured to move in and out of the snout 100 times a minute. This is partly achieved through the elasticity of the tongue and the conversion of elastic potential energy into kinetic energy
Kinetic energy
The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...
. The tongue is very flexible, particularly at the end, allowing it to bend in U-turns and catch insects attempting to flee in their twisty nests or mounds. The tongue also has an ability to avoid picking up splinters while foraging in logs; the reason for this ability is unknown. It can eat quickly; a specimen of around 3 kilograms (6.6 lb) can ingest 200 grams (7.1 oz) of termites in ten minutes.
The echidna has a stomach that is quite apart from other mammals. It is devoid of secretory glands and has cornified stratified epithelium, which resembles horny skin. Unlike other mammals, which typically have highly acidic stomachs, the Echidna has low levels of acidity, almost neutral with pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
in the 6.2–7.4 range. The stomach is elastic and the gastric peristalsis grinds dirt particulates and shredded insects together. The digestion occurs in the small intestine, which is around 3.4 metres (11.2 ft) in length. The insect exoskeletons and dirt are not digested and ejected in the waste.
Numerous physiological adaptations aid the lifestyle of the short-beaked echidna. Because the animal burrows, it must tolerate very high levels of carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
in inspired air, and will voluntarily remain in situations where carbon dioxide concentrations are high. It can dig up to a metre into the ground to retrieve ants or evade predators, and can survive with low oxygen when the area is engulfed by bushfires. The echidna can also dive underwater, an ability that can help it to survive sudden floods. During these situations, the heart rate drops to around 12 beats per minute, around one fifth of the rate at rest. This process is believed to save oxygen for the heart and brain, which are the most sensitive to such a shortage, and laboratory testing has revealed its cardiovascular system is similar to that of the seal.
The echidna's optical system is an uncommon hybrid of both mammalian and reptilian characteristics. The cartilaginous layer beneath the scleral layer of the eyeball is similar to that of reptiles and avians. The small cornea
Cornea
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Together with the lens, the cornea refracts light, with the cornea accounting for approximately two-thirds of the eye's total optical power. In humans, the refractive power of the cornea is...
's surface is keratinised and hardened, possibly an evolution to protect it from chemicals secreted by preyed insects or self-impalement when it rolls itself up, something that has been observed. The echidna has the flattest lens of any animal, giving it the longest focal length
Focal length
The focal length of an optical system is a measure of how strongly the system converges or diverges light. For an optical system in air, it is the distance over which initially collimated rays are brought to a focus...
. This similarity to primates and humans allows it to see distant objects clearly. Unlike placental mammals, including humans, the echidna does not have a ciliary muscle to distort the geometry of the lens and thereby change the focal length and allow objects at different distances to be viewed clearly; the whole eye is believed to distort so the distance between the lens and screen instead changes to allow focusing. The visual ability of an echidna is not great, and it is not known whether it can perceive colour; however, it can distinguish between black and white, and horizontal and vertical stripes. Eyesight is not a crucial factor in the animal's ability to survive, as blind echidnas are able to live healthily.
Its ear is sensitive to low-frequency
Frequency
Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...
sound, which may be ideal for detecting sounds emitted by termites and ants underground. The pinnae are obscured and covered by hair, so opponents can not grab them in an attack, and prey or foreign material cannot enter, although tick
Tick
Ticks are small arachnids in the order Ixodida, along with mites, constitute the subclass Acarina. Ticks are ectoparasites , living by hematophagy on the blood of mammals, birds, and sometimes reptiles and amphibians...
s are known to reside there. The ear has a macula
Macula
The macula or macula lutea is an oval-shaped highly pigmented yellow spot near the center of the retina of the human eye. It has a diameter of around 5 mm and is often histologically defined as having two or more layers of ganglion cells...
which is very large compared to other animals. It is used as a gravity sensor to orient the echidna. The large size is speculated to be due to importance of burrowing downwards for an echidna.
The leathery snout is keratinised and covered in mechano- and thermoreceptors, which provide information about the surrounding environment. These nerves protrude through microscopic holes at the end of the snout. It also has mucous glands on the end of the snout that act as electroreceptors. It can detect electric field
Electric field
In physics, an electric field surrounds electrically charged particles and time-varying magnetic fields. The electric field depicts the force exerted on other electrically charged objects by the electrically charged particle the field is surrounding...
s of 1.8 mV/cm—1,000 times more sensitive than humans—and dig up buried batteries. Echidnaa have a series of push rods protruding from their snouts. These are columns of flattened, spinous cells, with roughly an average diameter of 50 micrometres and a length of 300 micrometres. The number of push rods per square millimetre of skin is estimated to be 30 to 40. Longitudinal waves are believed to be picked up and transmitted through the rods, acting as mechanical sensors, to allow prey detection.
The short-beaked echidna has a well-developed olfactory system
Olfactory system
The olfactory system is the sensory system used for olfaction, or the sense of smell. Most mammals and reptiles have two distinct parts to their olfactory system: a main olfactory system and an accessory olfactory system. The main olfactory system detects volatile, airborne substances, while the...
, which may be used to detect mates and prey. It has a highly sensitive optic nerve
Optic nerve
The optic nerve, also called cranial nerve 2, transmits visual information from the retina to the brain. Derived from the embryonic retinal ganglion cell, a diverticulum located in the diencephalon, the optic nerve doesn't regenerate after transection.-Anatomy:The optic nerve is the second of...
, and has been shown to have visual discrimination and spatial memory
Spatial memory
In cognitive psychology and neuroscience, spatial memory is the part of memory responsible for recording information about one's environment and its spatial orientation. For example, a person's spatial memory is required in order to navigate around a familiar city, just as a rat's spatial memory is...
comparable to those of a rat
Rat
Rats are various medium-sized, long-tailed rodents of the superfamily Muroidea. "True rats" are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, and the brown rat, Rattus norvegicus...
. The brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
and central nervous system
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
have been extensively studied for evolutionary comparison with placental mammals, particularly with its fellow monotreme, the platypus. The average brain volume is 25 mL, similar to a cat of approximately the same size; while the platypus has a largely lissencephalic and smooth brain, the echidna has a heavily folded and fissured, gyrencephalic brain similar to humans, which is seen as a sign of a highly neurologically advanced animal. The cerebral cortex is thinner, the brain cells larger and more densely packed and organised in the echidna than the platypus, suggesting evolutionary divergence must have occurred long ago. Almost half of the sensory area in the brain is devoted to the snout and tongue, and the part devoted to smell is relatively large compared to other animals.
The short-beaked echidna has the largest prefrontal cortex
Prefrontal cortex
The prefrontal cortex is the anterior part of the frontal lobes of the brain, lying in front of the motor and premotor areas.This brain region has been implicated in planning complex cognitive behaviors, personality expression, decision making and moderating correct social behavior...
relative to body size of any mammal, taking up 50% of the cerebral cortex in comparison to 29% for humans. This part of the brain in humans is though to be used for planning and analytical behaviour, leading to debate as to whether the echidna has reasoning and strategising ability. Experiments in a simple maze and with a test on whether the animal can open a trap door to access food, and the echidna's ability to remember what it has learnt about the task for over a month, has led scientists to conclude its learning ability is similar to that of a cat or a rat.
The echidna shows rapid eye movement during sleep, usually around its thermoneutral temperature of 25°C, and this effect is suppressed at other temperatures. Its brain has been shown to contain a claustrum
Claustrum
The claustrum, which is suspected to be present in all mammals, is a fairly thin vertical curved sheet of subcortical gray matter...
similar to that of placental mammals, so linking this structure to their common ancestor
Common descent
In evolutionary biology, a group of organisms share common descent if they have a common ancestor. There is strong quantitative support for the theory that all living organisms on Earth are descended from a common ancestor....
.
Ecology and behaviour
No systematic study of the ecology of the short-beaked echidna has been published. There have, however, been studies of several aspects of their ecological behaviour. Short-beaked echidnas live alone, and, apart from the burrow created for rearing young, they have no fixed shelter or nest site. They do not have a home territory they defend against other echidnas, but range over a wide area. The range area has been observed to be between 21 and 93 ha, although one study in Kangaroo Island found the animals there covered an area between 9 and 192 ha. Overall, the mean range areas across the various regions of Australia were 40–60 ha. There was no correlation between gender and range area, but a weak one with size. Echidnas can share home ranges without incident, and sometimes share shelter sites if there are not enough for or each animal to have one individually.Short-beaked echidnas are typically active in the daytime, though they are ill-equipped to deal with heat because they have no sweat gland
Sweat gland
Sweat glands, or sudoriferous glands, are small tubular structures of the skin that produce sweat. There are two kinds of sweat glands:...
s and do not pant. Therefore, in warm weather, they change their patterns of activity, becoming crepuscular
Crepuscular
Crepuscular animals are those that are active primarily during twilight, that is during dawn and dusk. The word is derived from the Latin word crepusculum, meaning "twilight." Crepuscular is, thus, in contrast with diurnal and nocturnal behavior. Crepuscular animals may also be active on a bright...
or nocturnal. Body temperatures above 34 °C (93.2 °F) are believed to be fatal, and in addition to avoiding heat, the animal adjusts its circulation to maintain a sustainable temperature by moving blood to and from the skin to increase or lower heat loss. In areas where water is present, they can also swim to keep their body temperatures low. The "thermoneutral zone" for the environment is around 25 °C (77 °F), at which point metabolism needed to maintain body temperature is minimized. Echidnas can tolerate cold temperatures, and they hibernate during the winter both in cold regions and in regions with a more temperate climate. The echidna is endothermic, and can maintain body temperatures of around 32°C. It can also reduce its metabolism and heart rate and body temperature. In addition to brief and light bouts of torpor throughout the year, the echidna enters periods during winter when it hibernates. During periods of hibernation, the body temperature drops to as low as 4 °C (39.2 °F). The heart rate falls to 4–7 beats per minute—down from 50–68 at rest&mdash, and the echidna can breathe as infrequently as once every three minutes, 80 to 90% slower than when it is active. Metabolism can drop to one-eighth of the normal rate. Echidnas begin to prepare for the hibernation phase of the year between February and April, when they reduce their consumption and enter brief periods of torpor. Males begin hibernating first, while females that have reproduced start later. During the period of hibernation, the animals average 13 separate bouts of torpor, which are broken up by periods of arousal lasting 1.2 days on average. These interruptions tend to coincide with warmer periods. Males end their hibernation period in mid-June, while reproductive females return to full activity in July and August; nonreproductive females and immature echidnas may not end hibernation until two months later. During euthermia, the body temperature can vary by 4 °C (39.2 °F) per day. The metabolic rate is around 30% of that of placental mammals, making it the lowest energy-consuming mammal. This figure is similar to that of other animals that eat ants and termites; burrowing animals also tend to have low metabolism generally.
Questions have arisen as to why echidnas hibernate, as it is seemingly unnecessary for survival; they begin their hibernation period while the weather is still warm, and food is generally always plentiful. One explanation of this phenomenon is echidnas want to be cautious with their energy reserves to maximize their foraging productivity. Another hypothesis is they are descended from ectothermic ancestors, but have taken to periodic endothermy for reproductive reasons, so the young can develop more quickly. Supporters of this theory argue that males hibernate earlier than females because they finish their contribution to reproduction first, and they awake earlier to undergo spermatogenosis in preparation for mating, while females and young lag in their annual cycle. During the hibernation period, the animals stay in entirely covered shelter.
Short-beaked echidnas can live anywhere that has a good supply of food. They locate food by smell, using sensors in the tips of their snouts, and regularly feast on ants and termites. This view is based on the echidna's method of shuffling around seemingly arbitrarily, and using its snout in a probing manner. A study of Echidnas in New England has shown that they tend to dig up scarab beetle
Scarabaeidae
The family Scarabaeidae as currently defined consists of over 30,000 species of beetles worldwide. The species in this large family are often called scarabs or scarab beetles. The classification of this family is fairly unstable, with numerous competing theories, and new proposals appearing quite...
larvae in spring when the prey are active, but eschew this prey when it is inactive; this has been used to support the conjecture that Echidnas detect their prey using hearing. Vision is not believed to be significant in hunting, as blind animals have been observed to survive in the wild.
Echidnas use their strong claws to pull apart nests and rotting logs to gain access to their prey. They are selective of what types of ants and termites they target because some of their would-be prey secrete repulsive liquids. They also have a preference for the eggs, pupae and winged phases of the insects. Echidnas hunt most vigorously towards the end of winter and early in spring, when their fat reserves have been depleted after hibernation and/or nursing. At this time of the year, ants have high body fat, and the echidna targets their mounds. The animal also hunts beetles and earthworms, providing they are small enough to fit in a 5 mm gap. The proportion of ants and termites in their diet depends on the availability of prey, and termites make up a larger part in drier areas where they are more plentiful. However, termites are preferred, if available, as their bodies contain a smaller proportion of indigestible exoskeleton. Termites from the Rhinotermitidae
Rhinotermitidae
Rhinotermitidae is a family of termites . They feed on wood and can cause extensive damage to buildings or other wooden structures. About 345 species are recognized, among these are severe pests like Coptotermes formosanus, Coptotermes gestroi and Reticulitermes flavipes....
family, however, are avoided due to their chemical defenses. Scarab beetle larvae are also a large part of the diet when and where available. In a study conducted in New England
New England
New England is a region in the northeastern corner of the United States consisting of the six states of Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, and Connecticut...
in New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
, 37% of the food intake consisted of beetle larvae, although the echidna had to squash the prey in its snout as it ingested it, due to size.
Echidnas are powerful diggers, using their clawed front paws to dig out prey and create burrows for shelter. They may rapidly dig themselves into the ground if they cannot find cover when in danger. They bend their belly together to shield the soft, unprotected part, and can also urinate, giving off a pungent liquid, in an attempt to deter attackers. Males also have single small spurs on each rear leg that is believed to a defensive weapon that has since been lost to the evolutionary process. Echidnas typically try to avoid confrontation with predators due to their lack of anatomical weaponry. Instead, they use the colour of their spines, which is similar to the vegetation of the dry Australian environment, to avoid detection. They have good hearing and tend to become stationary if sound is detected.
In Australia, they are most common in forested areas where there are abundant, termite-filled, fallen logs. In agricultural areas, they are most likely to be found in uncleared scrub; they may be found in grassland, arid areas, and in the outer suburbs of the capital cities. Little is known about their distribution in New Guinea. They have been found in southern New Guinea between Merauke in the west and the Kelp Welsh River, east of Port Moresby
Port Moresby
Port Moresby , or Pot Mosbi in Tok Pisin, is the capital and largest city of Papua New Guinea . It is located on the shores of the Gulf of Papua, on the southeastern coast of the island of New Guinea, which made it a prime objective for conquest by the Imperial Japanese forces during 1942–43...
, in the east, where they may be found in open woodland.
Echidnas have the ability to swim, and have been seen cooling off near dams during high temperatures. They have also been seen crossing streams and swimming for brief periods in seas off Kangaroo Island. They swim with only the snout above water, using it as a snorkel.
Reproduction
Before mating, the male smells the female, paying particular attention to the cloaca
Cloaca
In zoological anatomy, a cloaca is the posterior opening that serves as the only such opening for the intestinal, reproductive, and urinary tracts of certain animal species...
. This process can take a few hours, and the female can reject the suitor by rolling herself into a ball. After prodding and sniffing her back, the male is often observed to roll the female onto her side and then assume a similar position himself so that the two animals are abdomen to abdomen, having dug a small crater to lie in. They can lie with heads facing one another, or head to rear. If more than one male is in the vicinity, there may be fighting over the female. Each side of the bilaterally symmetrical, rosette-like, four-headed penis [similar to that of reptiles and 7 centimetres (2.8 in) in length] is used alternately, with the other half being shut down between ejaculations. Sperm bundles of around 100 each appear to confer increased sperm motility, which may provide the potential for sperm competition between males. This process takes between a half an hour and three hours. Each mating results in the production of a single egg, and females are known to mate only once during the breeding season; each mating is successful.
Fertilisation occurs in the oviduct
Oviduct
In non-mammalian vertebrates, the passageway from the ovaries to the outside of the body is known as the oviduct. The eggs travel along the oviduct. These eggs will either be fertilized by sperm to become a zygote, or will degenerate in the body...
. Gestation
Gestation
Gestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals during pregnancy can have one or more gestations at the same time ....
takes between 21 and 28 days after copulation, during which time the female constructs a nursery burrow. Following the gestation period, a single, rubbery-skinned egg between 13 and 17 mm (0.511811023622047 and 0.669291338582677 ) in diameter and 1.5 and 2 g (0.0529109431576679 and 0.0705479242102239 oz) in weight is laid from her cloaca directly into a small, backward-facing pouch that has developed on her abdomen. The egg is ovoid, leathery, soft and cream-coloured. Between laying and hatching, some females continue to forage for food, while others dig burrows and rest there until hatching. Ten days after it is laid, the egg hatches within the pouch. The embryo develops an "egg tooth" during incubation, which it uses to tear open the egg; the tooth disappears soon after hatching.
Hatchlings are about 1.5 centimetre (0.590551181102362 in) long and weigh between 0.3 and 0.4 g (0.0105821886315336 and 0.0141095848420448 oz). After hatching, young echidnas are known as "puggles". Although newborns are still semitranslucent and still surrounded by the remains of the egg yolk, and the eyes are still barely developed, they already have well-defined front limbs and digits that allow them to climb on their mothers' bodies. Hatchlings attach themselves to their mothers' milk areolae, specialised patches on the skin that secrete milk—monotremes lack nipples—through approximately 100–150 pores. The puggles were thought to have imbibed the milk by licking the mother's skin, but this has been superseded by a belief they feed by sucking the areolae.
They have been observed ingesting large amounts during each feeding period, and mothers may leave them unattended in the burrow for between five and 10 days to find food. Studies of captives have shown they can ingest milk once every two or three days and then increase their mass by 20% in one milk-drinking session lasting between one and two hours. Around 40% of the milk weight is converted into body mass, and as such, a high proportion of milk is converted into growth; a correlation with the growth of the puggle and its mother's size has been observed. By the time the puggle is around 200 grams (7.1 oz), it is left in the burrow while the mother forages for food, and it reaches around 400 grams (14.1 oz) after around two months. Juveniles are eventually ejected from the pouch at around two to three months of age, because of the continuing growth in the length of their spines. During this period, the young are left in covered burrows while the mothers forage, and the young are often preyed upon. Suckling gradually decreases until juveniles are weaned at about six months of age. The duration of lactation is about 200 days, and the young leave the burrow after 180 to 205 days, usually in January or February, at which time they are around 800 and 1300 g (28.2 and 45.9 oz). There is no contact between the mother and young after this point.
The composition of the milk secreted by the mother changes over time. At the moment of birth, the solution is dilute and contains 1.25% fat, 7.85% protein, and 2.85% carbohydrates and minerals. Mature milk has much more concentrated nutrients, with 31.0, 12.4 and 2.8% of the aforementioned nutrients, respectively. Near weaning, the protein level continues to increase; this is conjectured to be due to the need for keratin synthesis for hair and spines, to provide defences against the cold weather and predators.
The principal carbohydrate components of the milk are fucosyllactose and saialyllactose; it has a high iron content, which gives it a pink colour. The high iron content and low levels of free lactose contrasts with other eutherian mammals. Lactose production is believed to proceed along the same lines as in the platypus.
The age of sexual maturity is uncertain, but may be four to five years. A 12-year field study, published in 2003, found the short-beaked echidna reaches sexual maturity between five and 12 years of age, and that the frequency of reproduction varies from once every two years to once every six years. The short-beaked echidna can live as long as 45 years in the wild, and the longest-lived echidna in captivity reached 49 years of age in a zoo in Philadelphia in the US. Echidnas contrast to other mammals in that their rates of reproduction and metabolism are lower, and they live longer, as though in slow motion, something caused, at least in part, by their low body temperature, which rarely exceeds 33°C, even when they are not hibernating.
Like its fellow monotreme the platypus, the short-beaked echidna has a system of multiple sex chromosomes
Sex-determination system
A sex-determination system is a biological system that determines the development of sexual characteristics in an organism. Most sexual organisms have two sexes. In many cases, sex determination is genetic: males and females have different alleles or even different genes that specify their sexual...
, in which males have four Y chromosome
Y chromosome
The Y chromosome is one of the two sex-determining chromosomes in most mammals, including humans. In mammals, it contains the gene SRY, which triggers testis development if present. The human Y chromosome is composed of about 60 million base pairs...
s and five X chromosome
X chromosome
The X chromosome is one of the two sex-determining chromosomes in many animal species, including mammals and is common in both males and females. It is a part of the XY sex-determination system and X0 sex-determination system...
s. Male individuals appear to be X1Y1X2Y2X3Y3X4Y4X5 (figure), while females are X1X1X2X2X3X3X4X4X5X5. Weak identity between chromosomes results in meiotic pairing
Meiosis
Meiosis is a special type of cell division necessary for sexual reproduction. The cells produced by meiosis are gametes or spores. The animals' gametes are called sperm and egg cells....
that yields only two possible genotype
Genotype
The genotype is the genetic makeup of a cell, an organism, or an individual usually with reference to a specific character under consideration...
s of sperm, X1X2X3X4X5 or Y1Y2Y3Y4, thus preserving this complex system.
Conservation status
Kangaroo Island
Kangaroo Island is Australia's third-largest island after Tasmania and Melville Island. It is southwest of Adelaide at the entrance of Gulf St Vincent. Its closest point to the mainland is off Cape Jervis, on the tip of the Fleurieu Peninsula in the state of South Australia. The island is long...
.
The most common threats to the animal in Australia are motor vehicles and habitat destruction, which have led to localized extinctions. In Australia, the number of short-beaked echidnas has been less affected by land clearance than have some other species, since they do not require a specialized habitat beyond a good supply of ants and termites. As a result, they can survive in cleared land if the cut-down wood is left in the area, as the logs can be used as shelter and a source of insects. However, areas where the land has been completely cleared for single crops that can be mechanically harvested, such as wheatfields, have seen extinctions. Over a decade-long period, around one-third of Echidna deaths reported to wildlife authorities in Victoria were due to motor vehicles, and the majority of wounded animals handed in were traffic accident victims. Studies have shown they often choose to traverse drainage culverts under roads, so this is seen as a viable means of reducing deaths on busy roads in rural areas or national parks where the animals are more common.
Despite their spines, they are preyed on by birds, the Tasmanian devil
Tasmanian Devil
The Tasmanian devil is a carnivorous marsupial of the family Dasyuridae, now found in the wild only on the Australian island state of Tasmania. The size of a small dog, it became the largest carnivorous marsupial in the world following the extinction of the thylacine in 1936...
, dingoes, snakes, lizards, goannas, cats and foxes, although almost all victims are young. Goannas are known for their digging abilities and strong sense of smell, and are believed to be have been the main predators of the echidna before the introduction of most of the other predators by European settlers. Dingoes are known to kill echidnas by rolling them over onto their backs and attacking their underbellies. A tracking study of a small number of echidnas on Kangaroo Island concluded goannas and cats were the main predators, although foxes—absent in Kangaroo Island—would be expected to be a major threat, also, as the echidna density in Tasmania—which is free from foxes—is higher in other parts of Australia.
They were eaten by indigenous Australians
Indigenous Australians
Indigenous Australians are the original inhabitants of the Australian continent and nearby islands. The Aboriginal Indigenous Australians migrated from the Indian continent around 75,000 to 100,000 years ago....
and the early European settlers of Australia. In contrast, hunting and eating of the echidna in New Guinea has increased over time and caused a decline in the population and distribution areas; it is now believed to have disappeared from highland areas. The killing of echidnas was a taboo in traditional culture, but since the tribespeople have become increasingly Christianised by western missionaries, hunting has increased, and the animals have been more easily tracked down due to the use of dogs.
Infection with the introduced parasite Spirometra erinaceieuropaei
Spirometra erinaceieuropaei
Spirometra erinaceieuropaei is a tapeworm that infects domestic animals and humans. In humans infection is called sparganosis. The worm has an interesting lifecycle, the adult worm is present in the small intestine of cats and dogs where it may grow as long as 1.5 metres. Eggs from the worm are...
is considered fatal for the echidna. This is a waterborne infection contracted through sharing drinking areas with infected dogs, foxes, cats and dingos, which do not die from the parasite. The infection is seen as being more dangerous in drier areas, where more animals are sharing fewer bodies of water, increasing the chance of transmission. The Wildlife Preservation Society of Queensland runs an Australia-wide survey, called Echidna Watch, to monitor the species in Australia. Echidnas are also known to be affected by tapeworms, protozoans and herpes-like viral infections, but there is little knowledge of how infections affect the health of the animals or the populations.
Although it considered easy to keep echidnas healthy in captivity, breeding is difficult, partly due to the relatively infrequent cycle. In 2009, Perth Zoo
Perth Zoo
The Perth Zoo is a zoo that opened in 1898 in South Perth, Western Australia. As of January 2011, it is home to 1258 animals of 164 species and includes an extensive botanical collection....
managed to breed some captive short-beaked echidnas. Until 2006, only five zoos have managed to breed a captive short-beaked echidna, but no captive-bred young have survived to maturity. Of these five institutions, only one in Australia—Sydney
Sydney
Sydney is the most populous city in Australia and the state capital of New South Wales. Sydney is located on Australia's south-east coast of the Tasman Sea. As of June 2010, the greater metropolitan area had an approximate population of 4.6 million people...
's Taronga Zoo
Taronga Zoo
Taronga Zoo is the city zoo of Sydney, New South Wales, Australia. Officially opened on 7 October 1916, it is located on the shores of Sydney Harbour in the suburb of Mosman...
—managed to breed echidnas, in 1977. The other four cases occurred in the Northern Hemisphere, two in the United States and the others in western Europe. In these cases, breeding occurred six months out of phase compared to Australia, after the animals had adapted to Northern Hemisphere seasons. The failure of captive breeding programs has conservation implications for the endangered species of echidna from the genus Zaglossus, and to a lesser extent for the short-beaked echidna.
Cultural references
Short-beaked echidnas feature in the animisticAnimism
Animism refers to the belief that non-human entities are spiritual beings, or at least embody some kind of life-principle....
culture of indigenous Australians, including their visual arts
Australian Aboriginal art
Indigenous Australian art is art made by the Indigenous peoples of Australia and in collaborations between Indigenous and Non-Indigenous Australians . It includes works in a wide range of media including painting on leaves, wood carving, rock carving, sculpture, ceremonial clothing and sandpainting...
and stories. The species was a totem for some groups, including the Noongar people
Noongar
The Noongar are an indigenous Australian people who live in the south-west corner of Western Australia from Geraldton on the west coast to Esperance on the south coast...
from Western Australia. Many groups have myths about the animal; one myth explains it was created when a group of hungry young men went hunting at night and stumbled across a wombat
Wombat
Wombats are Australian marsupials; they are short-legged, muscular quadrupeds, approximately in length with a short, stubby tail. They are adaptable in their habitat tolerances, and are found in forested, mountainous, and heathland areas of south-eastern Australia, including Tasmania, as well as...
. They threw spears at the wombat, but lost sight of it in the darkness. The wombat adapted the spears for its own defence and turned into an echidna. Another story tells of a greedy man who kept food from his tribe; warriors speared him and he crawled away into the bushes, where he turned into an echidna, the spears becoming his spines.
The short-beaked echidna is an iconic animal in contemporary Australia, notably appearing on the Australian five-cent coin (the smallest denomination), and on a AU
Australian dollar
The Australian dollar is the currency of the Commonwealth of Australia, including Christmas Island, Cocos Islands, and Norfolk Island, as well as the independent Pacific Island states of Kiribati, Nauru and Tuvalu...
$200 commemorative coin released in 1992. The short-beaked echidna has been included in several postal issues: it was one of four native species to appear on Australian postage stamps in 1974, when it was on the 25-cent stamp; it appeared on a 37-cent stamp in 1987, and in 1992 it was on the 35-cent stamp. The anthropomorphic echidna Millie was a mascot for the 2000 Summer Olympics. Knuckles the Echidna
Knuckles the Echidna
Knuckles the Echidna is a video game character of the Sonic the Hedgehog game series, including spin-off games and comics. His first appearance was in Sonic the Hedgehog 3, released in 1994 to introduce a new rival for Sonic. He was presented as an antagonist who was tricked by Dr. Eggman into...
, from the Sonic the Hedgehog
Sonic the Hedgehog
Sonic the Hedgehog may refer to:* Sonic the Hedgehog , a video game series released by Sega starring its eponymous mascot** Sonic the Hedgehog , a video game character and the main protagonist of the Sonic video game series released by Sega** Sonic the Hedgehog , a 1991 platform game developed by...
series is also based on the short-beaked echidna.
General references
- Augee, M. L. and Gooden, B. A. 1993. Echidnas of Australia and New Guinea. Australian National History Press, Sydney ISBN 978-0-86840-046-4
- Augee, M. L., Gooden, B. A. and Musser, A. 2006. Echidna : extraordinary egg-laying mammal. Collingwood, Victoria, CSIRO Publishing ISBN 0643092048
- Augee, M. L. 1983. R. Strahan Ed. The Australian Museum Complete Book of Australian Mammals. pp. 8–9. Angus & Robertson ISBN 0-207-14454-0
- Egerton, L. ed. 2005. Encyclopedia of Australian wildlife. Reader's Digest ISBN 1-876689-34-X
- Griffiths, M. 1989. Tachyglossidae. pp. 407–435 in Fauna of Australia (D. W. Walton and B. J. Richardson, eds.). Mammalia, Canberra, Australian Capital Territory 1B:1–1227.
External links
- Tasmanian Department of Water, Primary Industries and Environment - Short-beaked echidna
- Echidna Love Trains, article with sound clips and images of puggles
- Wildlife Preservation Society of Queensland - Echidna Watch
- Australian Mammal Species Files