Portia fimbriata
Encyclopedia
Portia fimbriata, sometimes called the fringed jumping spider, is a jumping spider
(family
Salticidae) found in Australia
and Southeast Asia
. Adult females have bodies 6.8 to 10.5 millimetres long, while those of adult males are 5.2 to 6.5 millimetres long. Both sexes have a generally dark brown carapace
, reddish brown chelicerae
("fangs"), a brown underside, dark brown palps
with white hairs, and dark brown abdomens with white spots on the upper side. Both sexes have fine, faint markings and soft fringes of hair, and the legs are spindly and fringed. However, specimens from New Guinea
and Indonesia
have orange-brown carapace
s and yellowish abdomen
s. In all species of the genus Portia
, the abdomen distends when the spider is well fed or producing eggs.
The hunting tactics of Portia are versatile and adaptable. All members of Portia have instinctive hunting tactics for their most common prey, but can improvise by trial and error against unfamiliar prey or in unfamiliar situations, and then remember the new approach. There are differences in the hunting tactics of the regional populations of P. fimbriata. Those in Australia's Northern Territory
are poor at hunting jumping spiders and better against non-salticid web-building spiders and against insect
s. The Sri Lanka
variant is fair against other jumping spiders, and good against web spiders and insects. P. fimbriata in Queensland
is an outstanding predator of other jumping spiders and of web spiders, but poor against insects. The Queensland variant use a unique "cryptic stalking" technique which prevents most jumping spider prey from identifying this P. fimbriata as a predator, or even as an animal at all. Some jumping spider prey have partial defences against the cryptic stalking technique. All types of prey spiders occasionally counter-attack, but all Portia species have very good defences, starting with especially tough skin.
When meeting another of the same species, P. fimbriata does not use cryptic stalking but displays by moving quickly and smoothly. In P. fimbriata from Queensland, contests between males usually are very brief and do no damage. Contests between Portia females are usually long and violent, and the victor may evict a loser and then eat the loser's eggs – but victorious females of P. fimbriata from Queensland do not kill and eat the losing female. If a P. fimbriata male from Queensland displays to a female, she may run away or she may charge at him. If the pair reach agreement after this, they will copulate if she is mature, and if she is sub-adult he will cohabit in her nest until she finishes moulting, and then they copulate. P. fimbriata typically copulates much quicker than other jumping spiders. Unlike in other Portia species, females of P. fimbriata do not eat their mates during courting, nor during or after copulation.
s in that the usual body segment
s are fused into only two tagmata
, the cephalothorax
and abdomen
. These are joined by a small, flexible pedicel
, which allows the abdomen to move while spinning silk. The top of the cephalothorax is covered by a carapace. In the genus
Portia
, the carapace slopes gently upward almost to the back, then steeply down.
In spiders and other chelicerates, there is only one pair of appendages before the mouth, the chelicerae
, and in spiders these house fangs that inject poison into the prey. Behind the mouth is a pair of pedipalp
s ("palps" for short), and those of male spiders are quite large and are used for displaying and mating.
Females of the jumping spider Portia fimbriata have bodies 6.8 to 10.5 millimetres long, while those of adult males are 5.2 to 6.5 millimetres long. The Queensland
variety is typically smaller than the Northern Territory variety. The cephalothorax
is about 4 millimetres long and 3 millimetres wide, and the abdomen about 4 millimetres long and 2.2 millimetres wide. The front of the cephalothorax is large and angular, and the face is broad, high and flat. In Australia
and Taiwan
, both sexes have a generally dark brown carapace
, reddish brown chelicerae ("jaws"), a brown underside, and dark brown palps
with white hairs. Both sexes also have fine, faint markings and soft fringes of hair. However, the female has a white fringe just above the chelicerae, while the back half of the male's cephalothorax has a white band round the bottom edge and a white groove down the back. While male spiders' palps are larger than females', the palps of P.fimbriata females have a fringe of hair that makes them look about as larger as males'. The abdomens of both sexes are dark brown, with white spots on the upper side. Wanless' female from New Guinea
has an orange carapace and chelicerae with sooty markings, palps mainly light yellow, legs orange-brown legs, and abdomen light yellow. Wanless also found a male from the Amboina area in Indonesia
, showing an orange-brown carapace and chelicerae, yellow-brown to orange-brown palps, orange-brown legs and a light yellowish abdomen. Like many spiders, all species of the genus Portia
have elastic abdomens, so that those of both sexes can become almost spherical when well fed, and females' can stretch as much when producing eggs.
("jaws"), which obscures the outlines of these appendages. When walking, all Portia species have a slow, "choppy" gait that preserves their concealment: pausing often and at irregular intervals; waving their legs continuously and their palps jerkily up and down; and moving each appendage out of time with the others and continuously varying the speed and timing. Portia′s walk is unlike that of any other spider, and this gait and the spider's fringes gives the appearance of light flickering through the forest canopy and reflecting from a piece of detritus. In Queensland
, P. fimbriata walks and waves more jerkily and about twice as slowly as other Portia species, including P. fimbriata in other areas.
In most species of spider, an individual lays a continuous dragline of non-sticky silk as the spider moves, and from time anchors the dragline to a surface with a spot of sticky silk. This allows the spider to return to the surface if the spider is dislodged. A spider about to jump first lays a sticky silk anchor, and then pays out a dragline as it flies.
If disturbed, most Portia species leap upwards about 100 to 150 millimetres, often from the cryptic rest pose, and often over a wide trajectory. Usually Portia then either freezes or runs about 100 millimetres and then freezes. However, P. fimbriata in Queensland rarely runs or leaps.
When isolated on little islands, Portia species can enter the water by slowly placing the forelegs in the surface of the water, pushing off with the back legs, and adopting a spreadeagle
position. A Portia then swims by moving one leg forward at a time.
's and 10 times more acute than a dragonfly
's. Jumping spiders have eight eyes, the two large ones in the center-and-front position (the anterior-median eyes, also called "principal eyes") housed in tubes in the cephalothorax and providing acute vision. The other six are secondary eyes, positioned along the sides of the carapace and acting mainly as movement detectors. In most jumping spiders, the middle pair of secondary eyes are very small and have no known function, but those of Portia species are relatively large, and function as well as those of the other secondary eyes.
The main eyes focus accurately on an object at distances from approximately 2 centimetres to infinity, and in practice can see up to about 75 centimetres. Like all jumping spiders, P. fimbriata can take in only a small visual field at one time, as the most acute part of a main eye can see all of a circle up to 12 millimeters wide at 20 centimeters away, or up to 18 millimeters wide at 30 centimeters away.
Generally the jumping spider
subfamily Spartaeinae
, which includes the genus
Portia
, cannot discriminate objects at such long distances as the members of subfamilies Salticinae or Lyssomaninae
can. However, the main eyes of Portia have vision about as acute as the best of the jumping spiders: the salticine Mogrus neglectus can distinguish prey and conspecifics up to 320 millimetres away (42 times its own body length), while P. fimbriata can distinguish these up to 280 millimetres (47 times its own body length). The main eyes of P. fimbriata can also identify features of the scenery up to 85 times its own body length, which helps the spider to find detours.
However, a Portia takes a relatively long time to see objects, possibly because getting a good image out of such tiny eyes is a complex process and needs a lot of scanning. This makes a Portia vulnerable to much larger predators such as bird
s, frog
s and mantis
es, which a Portia often cannot identify because of the other predator's size.
Spiders, like other arthropod
s, have sensors, often modified setae (bristles), for smell, taste, touch and vibration, protruding through their cuticle
("skin"). A Portia can sense vibrations from surfaces, and use these for mating and for hunting other spiders in total darkness. It can use air- and surface "smells" to detect prey which it often meets, to identify members of the same species, to recognise familiar members, and to determine the sex of other member of the same species.
have been called "eight-legged cats", as their hunting tactics are as versatile and adaptable as a lion's. All members of Portia have instinctive tactics for their most common prey, but can improvise by trial and error
against unfamiliar prey or in unfamiliar situations, and then remember the new approach. They can also make detours to find the best attack angle against dangerous prey, even when the best detour takes a Portia out of visual contact with the prey, and sometimes the planned route leads to abseiling
down a silk thread and biting the prey from behind. Such detours may take up to an hour, and a Portia usually picks the best route even if it needs to walk past an incorrect route.
While most jumping spiders prey mainly on insects and by active hunting, females of Portia also build webs to catch prey directly. These "capture webs" are funnel-shaped and widest at the top and are about 4,000 cubic centimetres in volume. A Portia often builds her own web on to one of a web-based non-salticid spider. When not joined to another spiders', a P. fimbriata female's capture web is generally suspended from rigid foundations such as boughs and rocks. Males of Portia do not build capture webs.
A Portia can pluck another spider's web with a virtually unlimited range of signals, either to lure the prey out into the open or calming the prey by monotonously repeating the same signal while the Portia walks slowly close enough to bite it. Such tactics enable Portia species to take web spiders from 10% to 200% of a Portia′s size, and Portia species hunt in all types of webs. In contrast, other cursorial spiders generally have difficulty moving on webs, and web-building spiders find it difficult to move in webs unlike those they build. When hunting in another spider's web, a Portia′s slow, choppy movements and the flaps on its legs make it resemble leaf detritus caught in the web and blown in a breeze. P. fimbriata and some other Portia species use breezes and other disturbances as "smokescreens" in which these predators can approach web spiders more quickly, and revert to a more cautious approach when the disturbance disappears. A few web spiders run far away when they sense the un-rhythmical gait of a Portia entering the web – a reaction Wilcox and Jackson call "Portia panic".
If a large insect is struggling in a web, Portia usually waits for up to a day until the insect stops struggling, even if the prey is thoroughly stuck. When an insect is stuck in a web owned by P. labiata, P. schultzi
or any regional variant of P. fimbriata, and next to a web spider's web, the web spider sometimes enters the Portia′s web, and the Portia pursues and catches the web spider.
The webs of spiders on which Portia species prey sometimes contain dead insects and other arthropods which are uneaten or partly eaten. P. fimbriata (in Queensland) and some other Portia species such as P. labiata and P. schultzi sometimes scavenge these corpses if the corpses are not obviously decayed.
When using its own web to catch other species of salticids, P. fimbriata conceals its conspicuous palps, which it does not do when stalking a web-spider or occasionally a moving fly.
All Portia species eat eggs of other spiders, including eggs of their own species and of other cursorial spiders, and can extract eggs from cases ranging from the flimsy ones of Pholcus
to the tough papery ones of Philoponella
. While only P. fimbriata (in Queensland) captures cursorial spiders in their nests, all Portia species steal eggs from empty nests of cursorial spiders.
The venom of Portia is unusually powerful against spiders. When a Portia stabs a small to medium spider (up to the Portia′s weight), including another Portia, the prey usually rans away for about 100 to 200 millimetres, enters convulsions, becomes paralysed after 10 to 30 seconds, and continues convulsing for 10 seconds to 4 minutes. Portia slowly approaches the prey and and takes it. Portia usually needs to inflict up to 15 stabbings to completely immobilise a larger spider (1.5 to 2 times to the Portia′s weight), and then Portia may wait about 20 to 200 millimetres away for 15 to 30 minutes from seizing the prey. Insects are usually not immobilised so quickly but continue to struggle, sometimes for several minutes.
Occasionally a Portia is killed or injured while pursuing prey up to twice Portia′s size. In tests, Portia labiata
is killed in 2.1% of pursuits and injured but not killed in 3.9%, while P. schultzi is killed in 1.7% and injured but not killed in 5.3%. In Queensland
, P. fimbriata is killed in 0.06% of its pursuits and injured but not killed in another 0.06%. A Portia′s especially tough skin often prevents injury, even when its body is caught in the other spider's fangs. When injured, Portia bleeds and may sometimes lose one or more legs. Spiders' palps and legs break off easily when attacked, Portia′s palps and legs break off exceptionally easily, which may be a defence mechanism, and Portia species are often seen with missing legs or palps, while other salticids in the same habitat are not seen with missing legs or palps. A P. fimbriata specimen, now in the Australian Museum collection, regenerated a lost limb about 7 days after moulting.
, the Northern Territory
and Sri Lanka
. The table also includes females of P. africana
around Lake Victoria
, of P. schultzi
elsewhere in Kenya
and of P. labiata
in Sri Lanka
for comparison.
(Q) !! P. fimbriata
(NT) !! P. fimbriata
(SL) !! P. africana !! P. labiata !! P. schultzi
|-
! rowspan="2" style="text-align:left; background:white;"| Salticid
| Tendency to pursue prey || style="text-align:center;"| 87% || style="text-align:center;"| 50% || style="text-align:center;"| 94% || style="text-align:center;"| 77% || style="text-align:center;"| 63% || style="text-align:center;"| 58%
|-
| Efficiency in capturing prey || style="text-align:center;"| 93% || style="text-align:center;"| 10% || style="text-align:center;"| 45% || style="text-align:center;"| 29% || style="text-align:center;"| 40% || style="text-align:center;"| 36%
|- style="background:#f4f4ff;"
! rowspan="2" style="text-align:left;"| Web-building
spider
| Tendency to pursue prey|| style="text-align:center;"| 91% || style="text-align:center;"| 94% || style="text-align:center;"| 64% || style="text-align:center;"| 74% || style="text-align:center;"| 83% || style="text-align:center;"| 84%
|- style="background:#f4f4ff;"
| Efficiency in capturing prey || style="text-align:center;"| 92% || style="text-align:center;"| 81% || style="text-align:center;"| 83% || style="text-align:center;"| 65% || style="text-align:center;"| 79% || style="text-align:center;"| 72%
|-
! rowspan="2" style="text-align:left; background:white;"| Insect
| Tendency to pursue prey || style="text-align:center;"| 27% || style="text-align:center;"| 30% || style="text-align:center;"| 43% || style="text-align:center;"| 48% || style="text-align:center;"| 35% || style="text-align:center;"| 52%
|-
| Efficiency in capturing prey || style="text-align:center;"| 41% || style="text-align:center;"| 83% || style="text-align:center;"| 78% || style="text-align:center;"| 67% || style="text-align:center;"| 71% || style="text-align:center;"| 69%
|-
| colspan="8" style="text-align:left;"|Notes on this table:
|}
Jumping spider
The jumping spider family contains more than 500 described genera and about 5,000 described species, making it the largest family of spiders with about 13% of all species. Jumping spiders have some of the best vision among invertebrates and use it in courtship, hunting and navigation...
(family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Salticidae) found in 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...
and Southeast Asia
Southeast Asia
Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...
. Adult females have bodies 6.8 to 10.5 millimetres long, while those of adult males are 5.2 to 6.5 millimetres long. Both sexes have a generally dark brown carapace
Carapace
A carapace is a dorsal section of the exoskeleton or shell in a number of animal groups, including arthropods such as crustaceans and arachnids, as well as vertebrates such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron.-Crustaceans:In crustaceans, the...
, reddish brown chelicerae
Chelicerae
The chelicerae are mouthparts of the Chelicerata, an arthropod subphylum that includes arachnids, Merostomata , and Pycnogonida . Chelicerae are pointed appendages which are used to grasp food, and are found in place of the chewing mandibles most other arthropods have...
("fangs"), a brown underside, dark brown palps
Pedipalp
Pedipalps , are the second pair of appendages of the prosoma in the subphylum Chelicerata. They are traditionally thought to be homologous with mandibles in Crustacea and insects, although more recent studies Pedipalps (commonly shortened to palps or palpi), are the second pair of appendages of the...
with white hairs, and dark brown abdomens with white spots on the upper side. Both sexes have fine, faint markings and soft fringes of hair, and the legs are spindly and fringed. However, specimens from 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...
and Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
have orange-brown carapace
Carapace
A carapace is a dorsal section of the exoskeleton or shell in a number of animal groups, including arthropods such as crustaceans and arachnids, as well as vertebrates such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron.-Crustaceans:In crustaceans, the...
s and yellowish abdomen
Abdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...
s. In all species of the genus Portia
Portia (genus)
Portia is a genus of jumping spider which feeds on other spiders . They are remarkable for their hunting behaviour which suggests they are capable of learning and problem solving, traits normally attributed to much larger animals....
, the abdomen distends when the spider is well fed or producing eggs.
The hunting tactics of Portia are versatile and adaptable. All members of Portia have instinctive hunting tactics for their most common prey, but can improvise by trial and error against unfamiliar prey or in unfamiliar situations, and then remember the new approach. There are differences in the hunting tactics of the regional populations of P. fimbriata. Those in Australia's Northern Territory
Northern Territory
The Northern Territory is a federal territory of Australia, occupying much of the centre of the mainland continent, as well as the central northern regions...
are poor at hunting jumping spiders and better against non-salticid web-building spiders and against insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s. The Sri Lanka
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...
variant is fair against other jumping spiders, and good against web spiders and insects. P. fimbriata in Queensland
Queensland
Queensland 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...
is an outstanding predator of other jumping spiders and of web spiders, but poor against insects. The Queensland variant use a unique "cryptic stalking" technique which prevents most jumping spider prey from identifying this P. fimbriata as a predator, or even as an animal at all. Some jumping spider prey have partial defences against the cryptic stalking technique. All types of prey spiders occasionally counter-attack, but all Portia species have very good defences, starting with especially tough skin.
When meeting another of the same species, P. fimbriata does not use cryptic stalking but displays by moving quickly and smoothly. In P. fimbriata from Queensland, contests between males usually are very brief and do no damage. Contests between Portia females are usually long and violent, and the victor may evict a loser and then eat the loser's eggs – but victorious females of P. fimbriata from Queensland do not kill and eat the losing female. If a P. fimbriata male from Queensland displays to a female, she may run away or she may charge at him. If the pair reach agreement after this, they will copulate if she is mature, and if she is sub-adult he will cohabit in her nest until she finishes moulting, and then they copulate. P. fimbriata typically copulates much quicker than other jumping spiders. Unlike in other Portia species, females of P. fimbriata do not eat their mates during courting, nor during or after copulation.
Body structure and appearance
Spiders are chelicerates, which differ from other arthropodArthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
s in that the usual body segment
Segmentation (biology)
Segmentation in biology refers to either a type of gastrointestinal motility or the division of some animal and plant body plans into a series of repetitive segments. This article will focus on the segmentation of animal body plans, specifically using the examples of the phyla Arthropoda,...
s are fused into only two tagmata
Tagma (biology)
In invertebrate biology, a tagma is a specialized grouping of arthropod segments, such as the head, the thorax, and the abdomen with a common function. The segments of a tagma may be either fused or moveable.-Tagmata:...
, the cephalothorax
Cephalothorax
The cephalothorax is a tagma of various arthropods, comprising the head and the thorax fused together, as distinct from the abdomen behind. The word cephalothorax is derived from the Greek words for head and thorax...
and abdomen
Abdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...
. These are joined by a small, flexible pedicel
Pedicel (spider)
The pedicel of a spider is a small, flexible cylinder that joins the cephalothorax and abdomen. This helps the spider to spin silk without moving the cephalothorax....
, which allows the abdomen to move while spinning silk. The top of the cephalothorax is covered by a carapace. In the 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...
Portia
Portia (genus)
Portia is a genus of jumping spider which feeds on other spiders . They are remarkable for their hunting behaviour which suggests they are capable of learning and problem solving, traits normally attributed to much larger animals....
, the carapace slopes gently upward almost to the back, then steeply down.
In spiders and other chelicerates, there is only one pair of appendages before the mouth, the chelicerae
Chelicerae
The chelicerae are mouthparts of the Chelicerata, an arthropod subphylum that includes arachnids, Merostomata , and Pycnogonida . Chelicerae are pointed appendages which are used to grasp food, and are found in place of the chewing mandibles most other arthropods have...
, and in spiders these house fangs that inject poison into the prey. Behind the mouth is a pair of pedipalp
Pedipalp
Pedipalps , are the second pair of appendages of the prosoma in the subphylum Chelicerata. They are traditionally thought to be homologous with mandibles in Crustacea and insects, although more recent studies Pedipalps (commonly shortened to palps or palpi), are the second pair of appendages of the...
s ("palps" for short), and those of male spiders are quite large and are used for displaying and mating.
Females of the jumping spider Portia fimbriata have bodies 6.8 to 10.5 millimetres long, while those of adult males are 5.2 to 6.5 millimetres long. The Queensland
Queensland
Queensland 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...
variety is typically smaller than the Northern Territory variety. The cephalothorax
Cephalothorax
The cephalothorax is a tagma of various arthropods, comprising the head and the thorax fused together, as distinct from the abdomen behind. The word cephalothorax is derived from the Greek words for head and thorax...
is about 4 millimetres long and 3 millimetres wide, and the abdomen about 4 millimetres long and 2.2 millimetres wide. The front of the cephalothorax is large and angular, and the face is broad, high and flat. In 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...
and Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
, both sexes have a generally dark brown carapace
Carapace
A carapace is a dorsal section of the exoskeleton or shell in a number of animal groups, including arthropods such as crustaceans and arachnids, as well as vertebrates such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron.-Crustaceans:In crustaceans, the...
, reddish brown chelicerae ("jaws"), a brown underside, and dark brown palps
Pedipalp
Pedipalps , are the second pair of appendages of the prosoma in the subphylum Chelicerata. They are traditionally thought to be homologous with mandibles in Crustacea and insects, although more recent studies Pedipalps (commonly shortened to palps or palpi), are the second pair of appendages of the...
with white hairs. Both sexes also have fine, faint markings and soft fringes of hair. However, the female has a white fringe just above the chelicerae, while the back half of the male's cephalothorax has a white band round the bottom edge and a white groove down the back. While male spiders' palps are larger than females', the palps of P.fimbriata females have a fringe of hair that makes them look about as larger as males'. The abdomens of both sexes are dark brown, with white spots on the upper side. Wanless' female from 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...
has an orange carapace and chelicerae with sooty markings, palps mainly light yellow, legs orange-brown legs, and abdomen light yellow. Wanless also found a male from the Amboina area in Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
, showing an orange-brown carapace and chelicerae, yellow-brown to orange-brown palps, orange-brown legs and a light yellowish abdomen. Like many spiders, all species of the genus Portia
Portia (genus)
Portia is a genus of jumping spider which feeds on other spiders . They are remarkable for their hunting behaviour which suggests they are capable of learning and problem solving, traits normally attributed to much larger animals....
have elastic abdomens, so that those of both sexes can become almost spherical when well fed, and females' can stretch as much when producing eggs.
Movement
When not hunting for prey or a mate, Portia species adopt a special posture, called the "cryptic rest posture", pulling their legs in close to the body and their palps back beside the cheliceraeChelicerae
The chelicerae are mouthparts of the Chelicerata, an arthropod subphylum that includes arachnids, Merostomata , and Pycnogonida . Chelicerae are pointed appendages which are used to grasp food, and are found in place of the chewing mandibles most other arthropods have...
("jaws"), which obscures the outlines of these appendages. When walking, all Portia species have a slow, "choppy" gait that preserves their concealment: pausing often and at irregular intervals; waving their legs continuously and their palps jerkily up and down; and moving each appendage out of time with the others and continuously varying the speed and timing. Portia′s walk is unlike that of any other spider, and this gait and the spider's fringes gives the appearance of light flickering through the forest canopy and reflecting from a piece of detritus. In Queensland
Queensland
Queensland 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...
, P. fimbriata walks and waves more jerkily and about twice as slowly as other Portia species, including P. fimbriata in other areas.
In most species of spider, an individual lays a continuous dragline of non-sticky silk as the spider moves, and from time anchors the dragline to a surface with a spot of sticky silk. This allows the spider to return to the surface if the spider is dislodged. A spider about to jump first lays a sticky silk anchor, and then pays out a dragline as it flies.
If disturbed, most Portia species leap upwards about 100 to 150 millimetres, often from the cryptic rest pose, and often over a wide trajectory. Usually Portia then either freezes or runs about 100 millimetres and then freezes. However, P. fimbriata in Queensland rarely runs or leaps.
When isolated on little islands, Portia species can enter the water by slowly placing the forelegs in the surface of the water, pushing off with the back legs, and adopting a spreadeagle
Spreadeagle (position)
The spread eagle is the position in which a person has his or her arms outstretched and legs apart, figuratively resembling an eagle with wings spread. It is a style that appears commonly in nature and geometry. In human style it is represented by the letter "X".A spreadeagle is a common position...
position. A Portia then swims by moving one leg forward at a time.
Senses
Although other spiders can also jump, salticids including Portia fimbriata have significantly better vision than other spiders, and their main eyes are more acute in daylight than a catCat
The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...
's and 10 times more acute than a dragonfly
Dragonfly
A dragonfly is a winged insect belonging to the order Odonata, the suborder Epiprocta or, in the strict sense, the infraorder Anisoptera . It is characterized by large multifaceted eyes, two pairs of strong transparent wings, and an elongated body...
's. Jumping spiders have eight eyes, the two large ones in the center-and-front position (the anterior-median eyes, also called "principal eyes") housed in tubes in the cephalothorax and providing acute vision. The other six are secondary eyes, positioned along the sides of the carapace and acting mainly as movement detectors. In most jumping spiders, the middle pair of secondary eyes are very small and have no known function, but those of Portia species are relatively large, and function as well as those of the other secondary eyes.
The main eyes focus accurately on an object at distances from approximately 2 centimetres to infinity, and in practice can see up to about 75 centimetres. Like all jumping spiders, P. fimbriata can take in only a small visual field at one time, as the most acute part of a main eye can see all of a circle up to 12 millimeters wide at 20 centimeters away, or up to 18 millimeters wide at 30 centimeters away.
Generally the jumping spider
Jumping spider
The jumping spider family contains more than 500 described genera and about 5,000 described species, making it the largest family of spiders with about 13% of all species. Jumping spiders have some of the best vision among invertebrates and use it in courtship, hunting and navigation...
subfamily Spartaeinae
Spartaeinae
The Spartaeinae are a subfamily of the spider family Salticidae . It was established by Fred R. Wanless in 1984 to include the groups Boetheae, Cocaleae, Lineae, Codeteae and Cyrbeae, which in turn were defined by Eugène Simon....
, which includes the 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...
Portia
Portia (genus)
Portia is a genus of jumping spider which feeds on other spiders . They are remarkable for their hunting behaviour which suggests they are capable of learning and problem solving, traits normally attributed to much larger animals....
, cannot discriminate objects at such long distances as the members of subfamilies Salticinae or Lyssomaninae
Lyssomaninae
The Lyssomaninae are a subfamily of jumping spiders, with eight described genera.The Lyssomaninae are not part of the Salticoida, to which over 90% of all salticid species belong.Six of these genera occur only in the Old World:* Asemonea O...
can. However, the main eyes of Portia have vision about as acute as the best of the jumping spiders: the salticine Mogrus neglectus can distinguish prey and conspecifics up to 320 millimetres away (42 times its own body length), while P. fimbriata can distinguish these up to 280 millimetres (47 times its own body length). The main eyes of P. fimbriata can also identify features of the scenery up to 85 times its own body length, which helps the spider to find detours.
However, a Portia takes a relatively long time to see objects, possibly because getting a good image out of such tiny eyes is a complex process and needs a lot of scanning. This makes a Portia vulnerable to much larger predators such as bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s, frog
Frog
Frogs are amphibians in the order Anura , formerly referred to as Salientia . Most frogs are characterized by a short body, webbed digits , protruding eyes and the absence of a tail...
s and mantis
Mantis
Mantis is the common name of any insect in the order Mantodea, also commonly known as praying mantises. The word itself means "prophet" in Latin and Greek...
es, which a Portia often cannot identify because of the other predator's size.
Spiders, like other arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
s, have sensors, often modified setae (bristles), for smell, taste, touch and vibration, protruding through their cuticle
Cuticle
A cuticle , or cuticula, is a term used for any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticles" are non-homologous; differing in their origin, structure, function, and chemical composition...
("skin"). A Portia can sense vibrations from surfaces, and use these for mating and for hunting other spiders in total darkness. It can use air- and surface "smells" to detect prey which it often meets, to identify members of the same species, to recognise familiar members, and to determine the sex of other member of the same species.
Hunting tactics of the genus Portia
Members of the genus PortiaPortia (genus)
Portia is a genus of jumping spider which feeds on other spiders . They are remarkable for their hunting behaviour which suggests they are capable of learning and problem solving, traits normally attributed to much larger animals....
have been called "eight-legged cats", as their hunting tactics are as versatile and adaptable as a lion's. All members of Portia have instinctive tactics for their most common prey, but can improvise by trial and error
Trial and error
Trial and error, or trial by error, is a general method of problem solving, fixing things, or for obtaining knowledge."Learning doesn't happen from failure itself but rather from analyzing the failure, making a change, and then trying again."...
against unfamiliar prey or in unfamiliar situations, and then remember the new approach. They can also make detours to find the best attack angle against dangerous prey, even when the best detour takes a Portia out of visual contact with the prey, and sometimes the planned route leads to abseiling
Abseiling
Abseiling , rappelling in American English, is the controlled descent down a rock face using a rope; climbers use this technique when a cliff or slope is too steep and/or dangerous to descend without protection.- Slang terms :...
down a silk thread and biting the prey from behind. Such detours may take up to an hour, and a Portia usually picks the best route even if it needs to walk past an incorrect route.
A Portia can pluck another spider's web with a virtually unlimited range of signals, either to lure the prey out into the open or calming the prey by monotonously repeating the same signal while the Portia walks slowly close enough to bite it. Such tactics enable Portia species to take web spiders from 10% to 200% of a Portia′s size, and Portia species hunt in all types of webs. In contrast, other cursorial spiders generally have difficulty moving on webs, and web-building spiders find it difficult to move in webs unlike those they build. When hunting in another spider's web, a Portia′s slow, choppy movements and the flaps on its legs make it resemble leaf detritus caught in the web and blown in a breeze. P. fimbriata and some other Portia species use breezes and other disturbances as "smokescreens" in which these predators can approach web spiders more quickly, and revert to a more cautious approach when the disturbance disappears. A few web spiders run far away when they sense the un-rhythmical gait of a Portia entering the web – a reaction Wilcox and Jackson call "Portia panic".
If a large insect is struggling in a web, Portia usually waits for up to a day until the insect stops struggling, even if the prey is thoroughly stuck. When an insect is stuck in a web owned by P. labiata, P. schultzi
Portia schultzi
Portia schultzi is a jumping spider which ranges from South Africa in the south to Kenya in the north, and also is found in West Africa and Madagascar. In this species, which is slightly smaller than some other species of the genus Portia, the bodies of females are 5 to 7 millimetres long, while...
or any regional variant of P. fimbriata, and next to a web spider's web, the web spider sometimes enters the Portia′s web, and the Portia pursues and catches the web spider.
The webs of spiders on which Portia species prey sometimes contain dead insects and other arthropods which are uneaten or partly eaten. P. fimbriata (in Queensland) and some other Portia species such as P. labiata and P. schultzi sometimes scavenge these corpses if the corpses are not obviously decayed.
When using its own web to catch other species of salticids, P. fimbriata conceals its conspicuous palps, which it does not do when stalking a web-spider or occasionally a moving fly.
All Portia species eat eggs of other spiders, including eggs of their own species and of other cursorial spiders, and can extract eggs from cases ranging from the flimsy ones of Pholcus
Pholcus
The spider genus Pholcus contains the Daddy long-legs spider P. phalangioides.Confusion often arises because the name "Daddy longlegs" is also applied to two other unrelated arthropods: the Harvestman and the Crane Fly....
to the tough papery ones of Philoponella
Philoponella
Philoponella is a genus of uloborid spiders. Like all Uloboridae, these species have no venom.The species P. vicinus uses its silk to crush its victims to death.-Cooperation:...
. While only P. fimbriata (in Queensland) captures cursorial spiders in their nests, all Portia species steal eggs from empty nests of cursorial spiders.
The venom of Portia is unusually powerful against spiders. When a Portia stabs a small to medium spider (up to the Portia′s weight), including another Portia, the prey usually rans away for about 100 to 200 millimetres, enters convulsions, becomes paralysed after 10 to 30 seconds, and continues convulsing for 10 seconds to 4 minutes. Portia slowly approaches the prey and and takes it. Portia usually needs to inflict up to 15 stabbings to completely immobilise a larger spider (1.5 to 2 times to the Portia′s weight), and then Portia may wait about 20 to 200 millimetres away for 15 to 30 minutes from seizing the prey. Insects are usually not immobilised so quickly but continue to struggle, sometimes for several minutes.
Occasionally a Portia is killed or injured while pursuing prey up to twice Portia′s size. In tests, Portia labiata
Portia labiata
Portia labiata is a jumping spider found in Sri Lanka, India, Burma , Malaysia, Singapore, Java, Sumatra and the Philippines. In this medium-sized jumping spider, the front part is orange-brown and the back part is brownish...
is killed in 2.1% of pursuits and injured but not killed in 3.9%, while P. schultzi is killed in 1.7% and injured but not killed in 5.3%. In Queensland
Queensland
Queensland 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...
, P. fimbriata is killed in 0.06% of its pursuits and injured but not killed in another 0.06%. A Portia′s especially tough skin often prevents injury, even when its body is caught in the other spider's fangs. When injured, Portia bleeds and may sometimes lose one or more legs. Spiders' palps and legs break off easily when attacked, Portia′s palps and legs break off exceptionally easily, which may be a defence mechanism, and Portia species are often seen with missing legs or palps, while other salticids in the same habitat are not seen with missing legs or palps. A P. fimbriata specimen, now in the Australian Museum collection, regenerated a lost limb about 7 days after moulting.
Hunting tactics of P. fimbriata
All performance statistics summarise result of tests in a laboratory, using captive specimens. Female P. fimbriatas' tactics and performance show regional differences between the populations in QueenslandQueensland
Queensland 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...
, the Northern Territory
Northern Territory
The 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 Sri Lanka
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...
. The table also includes females of P. africana
Portia africana
Portia africana is a jumping spider found in Angola, Cameroon, the Central African Republic, Gabon, Ghana, the Ivory Coast, Sierra Leone, Zaire and Zambia. Its conspicuous main eyes provide vision more acute than a cat's during the day and 10 times more acute than a dragonfly's, and this is...
around Lake Victoria
Lake Victoria
Lake Victoria is one of the African Great Lakes. The lake was named for Queen Victoria of the United Kingdom, by John Hanning Speke, the first European to discover this lake....
, of P. schultzi
Portia schultzi
Portia schultzi is a jumping spider which ranges from South Africa in the south to Kenya in the north, and also is found in West Africa and Madagascar. In this species, which is slightly smaller than some other species of the genus Portia, the bodies of females are 5 to 7 millimetres long, while...
elsewhere in Kenya
Kenya
Kenya , officially known as the Republic of Kenya, is a country in East Africa that lies on the equator, with the Indian Ocean to its south-east...
and of P. labiata
Portia labiata
Portia labiata is a jumping spider found in Sri Lanka, India, Burma , Malaysia, Singapore, Java, Sumatra and the Philippines. In this medium-sized jumping spider, the front part is orange-brown and the back part is brownish...
in Sri Lanka
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...
for comparison.
(Q) !! P. fimbriata
(NT) !! P. fimbriata
(SL) !! P. africana !! P. labiata !! P. schultzi
|-
! rowspan="2" style="text-align:left; background:white;"| Salticid
| Tendency to pursue prey || style="text-align:center;"| 87% || style="text-align:center;"| 50% || style="text-align:center;"| 94% || style="text-align:center;"| 77% || style="text-align:center;"| 63% || style="text-align:center;"| 58%
|-
| Efficiency in capturing prey || style="text-align:center;"| 93% || style="text-align:center;"| 10% || style="text-align:center;"| 45% || style="text-align:center;"| 29% || style="text-align:center;"| 40% || style="text-align:center;"| 36%
|- style="background:#f4f4ff;"
! rowspan="2" style="text-align:left;"| Web-building
spider
| Tendency to pursue prey|| style="text-align:center;"| 91% || style="text-align:center;"| 94% || style="text-align:center;"| 64% || style="text-align:center;"| 74% || style="text-align:center;"| 83% || style="text-align:center;"| 84%
|- style="background:#f4f4ff;"
| Efficiency in capturing prey || style="text-align:center;"| 92% || style="text-align:center;"| 81% || style="text-align:center;"| 83% || style="text-align:center;"| 65% || style="text-align:center;"| 79% || style="text-align:center;"| 72%
|-
! rowspan="2" style="text-align:left; background:white;"| Insect
| Tendency to pursue prey || style="text-align:center;"| 27% || style="text-align:center;"| 30% || style="text-align:center;"| 43% || style="text-align:center;"| 48% || style="text-align:center;"| 35% || style="text-align:center;"| 52%
|-
| Efficiency in capturing prey || style="text-align:center;"| 41% || style="text-align:center;"| 83% || style="text-align:center;"| 78% || style="text-align:center;"| 67% || style="text-align:center;"| 71% || style="text-align:center;"| 69%
|-
| colspan="8" style="text-align:left;"|Notes on this table:
- "Tendency to pursue prey" is the percentage of tests in which the subject pursues the potential prey, and a pursuit starts when the Portia either approaches the prey or shakes the prey's web.
- "Efficiency in capturing prey" is the percentage of pursuits in which the subject captures the prey.
- "(Q)", "(NT)" and "(SL)" identify P. fimbriatas from Queensland, Northern Territory and Sri Lanka.
- The prey used were: unspecified jumping spiders; amaurobiid and theridiidTheridiidaeTheridiidae is a large family of spiders, also known as the tangle-web spiders, cobweb spiders and comb-footed spiders. The diverse family includes over 2200 species in over 100 genera) of three-dimensional space-web-builders found throughout the world...
web-based spiders; and housefliesHouseflyThe housefly , Musca domestica, is a fly of the suborder Cyclorrhapha...
.
|}
P. fimbriata in all regions fix their own webs to solid surfaces such as rocks and tree trunks and boughs, while some other Portia species often fix their webs to pliant stems and leaves and on the lower branches of trees.
A test in 2001 showed that four jumping species take nectar, either by sucking free nectar from the surface of flowers or biting the flowers with their fangs. The spiders fed in cycles of two to four minutes, then groomed their bodies and especially their chelicerae, before another cycle. A more formal part of the test showed that 90 juvenile jumping spiders, including P. fimbriata, generally prefer to suck from blotting soaked with a 30% solution of sugar rather than paper soaked with distilled water. The authors suggest that, in the wild, nectar may be a frequent, convenient way to get some nutrients, as it would avoid the work, risks and costs (such as making venom) of predation. Jumping spiders may benefit from amino acids, lipids, vitamin
Vitamin
A vitamin is an organic compound required as a nutrient in tiny amounts by an organism. In other words, an organic chemical compound is called a vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained from the diet. Thus, the term is conditional both on...
s and minerals normally found in nectar.
Tactics in Queensland
Portia fimbriata from Queensland is the most thoroughly studied araneophagic (spider-eating) salticid. Robinson (2010) said that the Queensland P. fimbriata has the most varied prey capture techniques of any animal in the world except humans and other simianSimian
The simians are the "higher primates" familiar to most people: the Old World monkeys and apes, including humans, , and the New World monkeys or platyrrhines. Simians tend to be larger than the "lower primates" or prosimians.- Classification and evolution :The simians are split into three groups...
s. When not using its own web, the Queensland P. fimbriata preys mainly on salticids of other genera, generally using against them a special tactic called "cryptic stalking".
More likely to vibrate the web
Less likely to leap
| Less efficient
Less likely to vibrate the web
More likely to leap
|-
! Abundance of local salticids
| Higher || Lower
|-
! Preying on cursorial salticids
| More efficient
Uses cryptic stalking
Usually swoops
| Less efficient
No use of cryptic stalking
Never swoops
|-
! Pursuing and catching insects
| Less efficient || More efficient
|-
! Slow, mechanical walking
| Exaggerated || Less pronounced
|-
! When mildly disturbed
| Adopts cryptic pose || Makes wild leaps
|-
! While mating
| Courtship uses less vibrations
Female seldom twists to
lunge and eat the male
| Courtship uses more vibrations
Female twists and lunges
and often eats the male
|-
| colspan="3" style="text-align:left;"|Notes on this table:
- In a swoop, P. fimbriata in Queensland slowly moves its cephalothorax above the prey, and then quickly drives down with its fangs open. This type of attack is not used by other Portia species, including P. fimbriata from Northern Territory and Sri Lanka.
- Other Portia species, including P. fimbriata outside Queensland, occasionally use isolated aspects of cryptic stalking, such as briefly keeping the palps down or being still for a moment when very close to prey.
|}
Adult males are less ready to pursue and less efficient at catching than adult females, especially against larger prey. Males are quite effective against small web spiders, and reluctant to tackle large ones although they catch them in about 50% of attempts. Against other jumping spiders, males do not pursue large ones and pursue about 48% of small ones, catching 84% of those they pursue. Males of Portia do not build large webs for catching prey ("capture webs").
A test in 1997 showed that P. fimbriata′s preferences for different types of prey are in the order: web spiders; jumping spiders; and insects. These preferences apply to both live prey and motionless lures, and to P. fimbriata specimens without prey for 7 days ("well-fed") and without prey for 14 days ("starved"). P. fimbriata specimens without prey for 21 days ("extra-starved") showed no preference for different types of prey. The test included as prey several species of web spiders and jumping spiders, and the selection of the prey species showed no evidence of affecting the results. Insects were represented by the house fly Musca domestica.
| Prey | P. fimbriata (Q) | Other Portia species | |
|---|---|---|---|
| Salticid | Median Median In probability theory and statistics, a median is described as the numerical value separating the higher half of a sample, a population, or a probability distribution, from the lower half. The median of a finite list of numbers can be found by arranging all the observations from lowest value to... |
26 min | 3 min |
| Range | 1 to 318 min | 0 to 41 min | |
| Web spider | Median Median In probability theory and statistics, a median is described as the numerical value separating the higher half of a sample, a population, or a probability distribution, from the lower half. The median of a finite list of numbers can be found by arranging all the observations from lowest value to... |
16 min | 5 min |
| Range | 0 to 583 min | 0 to 465 min | |
| Insect | Median Median In probability theory and statistics, a median is described as the numerical value separating the higher half of a sample, a population, or a probability distribution, from the lower half. The median of a finite list of numbers can be found by arranging all the observations from lowest value to... |
3 min | 3 min |
| Range | 0 to 34 min | 0 to 45 min |
When hunting most other salticids in Queensland, P. fimbriata exaggerates the slowness and "choppiness" of its normal gait (sometimes called "robotlike") and holds its palps retracted beside its fangs, as it also does in the cryptic rest pose. If the salticid prey faces P. fimbriata, P. fimbriata freezes until the prey turns away. This "cryptic stalking" appears unique to Queensland, where most other jumping spiders fail to recognize a disguised stalking P. fimbriata as a predator, or even as an animal at all. P. fimbriata from Queensland uses cryptic stalking against both salticids native to Queensland and against imported salticids. Other salticids often defend themselves when stalked by other species of Portia or by P. fimbriata outside Queensland, and the Queensland P. fimbriata′s cryptic stalking may be a regional adaptation to the abundant but dangerous salticid prey, especially Jacksonoides queenslandicus, in the local rainforest. P. fimbriata uses cryptic stalking even against some oddly-shaped salticids such as the flattened Holoplatys and the elongated, mantis
Mantis
Mantis is the common name of any insect in the order Mantodea, also commonly known as praying mantises. The word itself means "prophet" in Latin and Greek...
-like Mantisatta longicauda. All of P. fimbriata′s salticid prey have a pair of large, forward-facing principal eyes, a feature that arachnologists also use to distinguish salticids from all other spiders.
Euryattus
Euryattus
Euryattus is a genus of the spider family Salticidae .Like Holcolaetis and Thiania bhamoensis, these spiders build a flat, densely woven egg sac that is not contiguous with the silk of the nest. Euryattus posits the egg sac in rolled up leaves, similar to T...
, another jumping spider from Queensland, has a partly overlapping range with P. fimbriata′s and is abundant in their common range, and adult and large juvenile P. fimbriatas hunt Euryattus adopting specific tactics. Unlike most jumping spiders, Euryattus makes a nest by suspending a dead rolled-up leaf by silk lines from vegetation. P. fimbriata catches Euryattus females by mimicking the vibrations made by Euryattus males as part of their courtship, and this deception lures Euryattus females out of their nests. In tests, a Euryattus from P. fimbriata′s range recognises the predator and defends itself, while Euryattus specimens from outside P. fimbriata′s range seldom recognise the threat. P. fimbriata finds it easier to catch a Euryattus from outside the predator's home range than to capture the same species from P. fimbriata′s range. This may be an example of a evolutionary arms race
Evolutionary arms race
In evolutionary biology, an evolutionary arms race is an evolutionary struggle between competing sets of co-evolving genes that develop adaptations and counter-adaptations against each other, resembling an arms race, which are also examples of positive feedback...
.
P. fimbriata does not stalk at all species of the ant
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...
-mimic
Mimic
In evolutionary biology, mimicry is the similarity of one species to another which protects one or both. This similarity can be in appearance, behaviour, sound, scent and even location, with the mimics found in similar places to their models....
jumping spider genus Myrmarachne
Myrmarachne
Myrmarachne is a genus of jumping spiders which imitate an ant by waving their front legs in the air to simulate antennae. Some species also look strikingly like ants....
, and uses cryptic stalking only about 20% of the time against other ant-mimicking salticids and against beetle
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
-mimicking salticids. P. fimbriata also sometimes does not use cryptic stalking against females of the salticid subfamily Lyssomaninae
Lyssomaninae
The Lyssomaninae are a subfamily of jumping spiders, with eight described genera.The Lyssomaninae are not part of the Salticoida, to which over 90% of all salticid species belong.Six of these genera occur only in the Old World:* Asemonea O...
. These females are unusually translucent, and the translucent cuticle makes the anterior-median eyes (front-and-center) show light and dark regions that flicker in and out when viewed head on. Lyssomanine males are not translucent and do not produce this flickering, and P. fimbriata uses cryptic stalking consistently against the males. This suggests that the flickering anterior-median eyes of lyssomanine females may reduce the ability of P. fimbriata to identify these females as jumping spiders.
When encountering J. queenlandicus, P. fimbriata often first notices chemical cues on J. queenlandicus′ silken safety lines and then looks for its prey. The smell makes P. fimbriata to quicker to see the prey, possibly by lowering thresholds
Sensory threshold
Sensory threshold is a theoretical concept used in psychophysics. A stimulus that is less intense than the sensory threshold will not elicit any sensation...
in the visual system. Sometimes P. fimbriata cannot see J. queenlandicus through the prey's camouflage, and "hunts by speculation", jumping high in the air, so that J. queenlandicus betrays itself by turning and looking for the disturbance. P. fimbriata then turns toward J. queenslandicus and waves its palps. It appears that only P. fimbriatas from Queensland behaves this way while Portia species from other areas did not, that P. fimbriata from Queensland reacts this way only to J. queenslandicus, and that J. queenslandicus perceives no chemical warnings that P. fimbriata is around.
When stalking any non-salticid, P. fimbriata does not use cryptic stalking and does not consistently pull its palps back nor consistently freeze when faced by the prey. P. fimbriata adopts cryptic stalking only after recognizing prey as a jumping spider.
In Queensland, P. fimbriata is reluctant to jump into the webs of prey spiders, while other Portia species do this at any opportunity. The Queensland orb web spider Argiope appensa shakes it web violently to shake of intruders, and P. fimbriata finds a detour that allows it to abseil on to the prey. When the web spider Zosis genicularis is busy wrapping up its own prey and is less aware of other predators, P. fimbriata uses this activity as a type of smokescreen to approach the web spider.
P. fimbriata uses non-cryptic stalking against lycosid, clubionid, theridiid
Theridiidae
Theridiidae is a large family of spiders, also known as the tangle-web spiders, cobweb spiders and comb-footed spiders. The diverse family includes over 2200 species in over 100 genera) of three-dimensional space-web-builders found throughout the world...
and desid spiders, and against flies, but does not stalk beetles or ants.
Unlike other Portia species, P. fimbriata in Queensland readily invades the nests of cursorial
Cursorial
Cursorial is a biological term that describes an organism as being adapted specifically to run. It is typically used in conjunction with an animal's feeding habits or another important adaptation. For example, a horse can be considered a "cursorial grazer", while a wolf may be considered a...
spiders, plucking or cutting the nest. If the resident spider eventually leaves the nest, P. fimbriata stalks it. If the resident spider tries to counterattack and then retreats into the nest, P. fimbriata may attack the other spider as it re-enters the nest, or may wait motionless until the prey exits. If a stabbed prey spider retreats into the nest, P. fimbriata in Queensland never enters the nest, but waits for the prey to move out, and then P. fimbriata kills it.
A test in a deliberately artificial environment explored the Queensland P. fimbriata′s ability to solve a novel problem by trial and error. A little island was set up in the middle of a miniature atoll, and the space between with them was filled with water. The gap was too wide for the spiders to jump all the way, and the spiders' options were to leap and then swim or to swim only. The testers encouraged some specimens by using a tiny scoop to make waves toward the atoll when the spiders chose the option the testers preferred (leap and then swim, or swim only), and discouraged some specimens by making waves back toward the island when the spiders chose the option the testers did not want – in other words, the testers "rewarded" one group for "successful" behaviour and "penalised" the other group for "unwanted" behaviour. The Queensland P. fimbriata specimens generally repeated successful behaviour and switched if the first try was unsuccessful, irrespective of which option (leap and then swim or to swim only) the testers chose as "good" for each specimen.
Tactics in Northern Territory
In the Northern Territory, P. fimbriata has no special tactics against other jumping spiders and tries to treat them as if they were web spiders, and then either tries to jump on them or gives up. Hence this variant is poor at catching other jumping spiders. The Northern Territory variant of P. fimbriata is not as good as the Queensland one as catching web spiders, but better than the Sri Lanka variant and some other species of Portia. It is not enthusiastic about pursuing insects, but very good at catching those it pursues, as the performance table above shows While pursuits by the Queensland variant typically take 26 minutes, those of the Northern Territory variant typically take 3 to 5 minutes, like some other species of Portia.Tactics in Sri Lanka
The Sri Lanka variant enthusiastically pursues other jumping spiders and is slightly better than most Portia species in tests, but about half as effective as the Queensland variant. In Sri Lanka, P. fimbriata is not a prolific hunter of web spiders or insects, but quite efficiently catches those it pursues. Like other Portia species, the Sri Lanka P. fimbriata typically take 3 to 5 minutes for a pursuit.Reproduction and lifecycle
Before courtshipCourtship
Courtship is the period in a couple's relationship which precedes their engagement and marriage, or establishment of an agreed relationship of a more enduring kind. In courtship, a couple get to know each other and decide if there will be an engagement or other such agreement...
, a male Portia spins a small web between boughs or twigs, and he hangs under that and ejaculates on to it. He then soaks the semen
Semen
Semen is an organic fluid, also known as seminal fluid, that may contain spermatozoa. It is secreted by the gonads and other sexual organs of male or hermaphroditic animals and can fertilize female ova...
into reservoirs on his pedipalp
Pedipalp
Pedipalps , are the second pair of appendages of the prosoma in the subphylum Chelicerata. They are traditionally thought to be homologous with mandibles in Crustacea and insects, although more recent studies Pedipalps (commonly shortened to palps or palpi), are the second pair of appendages of the...
s, which are larger than those of females.
A laboratory test showed how males of P. fimbriata from Queensland minimise the risk of meeting each other, by recognising fresh pieces of blotting paper, some containing their own silk draglines and some containing another male's draglines. Males also were attracted by fresh blotting paper containing females' draglines, while females do not response to fresh blotting paper containing males' draglines. This suggested that the males usually search for females, rather than vice versa. Neither sex responded to one week-old blotting paper, irrespective of whether it contained males' or females' draglines. A similar series of tests showed that P. labiata showed the same patterns of responses between the sexes.
When meeting another of the same species, P. fimbriata does not stalk but displays by moving quickly and smoothly, and displays at 4 to 27 centimetres away. It raises its legs, its body sways from side to side, and the palps are lowered below the chelicerae ("fangs"). This is very different from the stalking it uses when encountering another salticid of a different species, despite receiving the same visual stimulus, the sight of the other's large anterior-median eyes. Although P. fimbriata is influenced by pheromones much more than is usual among salticids, visual cues alone are enough to start displays and distinguish members of the same species from other salticids, even if neither partner moves. The spindly, fringed legs of Portia species may identify members of the same species, as well as concealing these spiders from other salticid species.
In P. fimbriata from Queensland and in some other species, contests between males usually last only 5 to 10 seconds, and only their legs make contact. Contests between Portia females are usually long and violent, and in P. fimbriata from Queensland these often including grappling that sometimes breaks a leg. A victor may evict a loser, and then eat the loser's eggs and take over the loser's web. Unlike in some other Portia species, victorious females of P. fimbriata from Queensland do not kill and eat the losers.
A female that sees a male may approach slowly or wait. The male then walks erect and displays by waving his legs and palps. If the female does not run away, she gives a "propulsive display" first. If the male stands his ground and she does not ran away or repeat the propulsive display, he approaches and, if she is mature, they copulate. If the female is sub-adult (one moult from maturity), a male or sometimes a sub-adult male of P. fimbriata may cohabit in the female's capture web. Portia species usually mate on a web or on a dragline made by the female. P. fimbriata typically copulates for about 100 seconds, while other genera can take several minutes or even several hours. Unlike in some other Portia species, females of P. fimbriata from Queensland do not eat their mates during courting, nor during or after copulation.
When hunting, mature females of P. fimbriata, P. africana, P. fimbriata, P. labiata, and P. schultzi emit olfactory signals that reduce the risk that any other females, males or juveniles of the same species may contend for the same prey. The effect inhibits aggressive mimicry against a prey spider even if the prey spider is visible, and also if the prey is inhabiting any part of a web. If a female of one of these Portias smells a male of the same species, the female stimulates the males to court. These Portia species do not show this behaviour when they receive olfactory signals from members of other Portia species.
In laboratory tests, Portia species including P. fimbriata mate with other species, but the females then produce no eggs.
P. fimbriata in Queensland prefers to lay eggs on dead, brown leaves about 20 millimetres long, suspended near the top of its capture web, and then cover the eggs with a sheet of silk. If there is no dead leaf available, the female will make a small horizontal silk platform in the capture web, lay the eggs on it, and then cover the eggs. In Northern Territory, P. fimbriata occasionally lays eggs in a dead leaf, but more usually in a silk egg sac on a small horizontal web suspended on the main web.
Like all all arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
s, spiders moult and, after hatching, the life stage before each moult is called an "instar
Instar
An instar is a developmental stage of arthropods, such as insects, between each molt , until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or assume a new form. Differences between instars can often be seen in altered body proportions, colors, patterns, or...
". Specimens of P. fimbriata become mature at instar 7, 8 or 9. In an experiment using P. fimbriata spiderlings from Queensland, 64% of those fed only on spiders survived to maturity, 37% of those fed on a mixture of spiders and insects survived, and all those fed solely on insects died before reaching the 6th instar. For moult
Moult
In biology, moulting or molting , also known as sloughing, shedding, or for some species, ecdysis, is the manner in which an animal routinely casts off a part of its body , either at specific times of year, or at specific points in its life cycle.Moulting can involve the epidermis , pelage...
ing, all Portia species spin a horizontal web whose diameter is about twice the spider's body length and is suspended only 1 to 4 millimetres below a leaf. The spider lies head down, and often slides down 20 to 30 millimetres during moulting. Portia species spin a similar temporary web for resting. P. fimbriata in Queensland can be very sedentary, in some cases remaining in the same web for over 48 days during a series of moults.
Ecology
P. fimbriata is found in the rain forests of IndiaIndia
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
, Nepal
Nepal
Nepal , officially the Federal Democratic Republic of Nepal, is a landlocked sovereign state located in South Asia. It is located in the Himalayas and bordered to the north by the People's Republic of China, and to the south, east, and west by the Republic of India...
, Sri Lanka
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...
, Hong Kong
Hong Kong
Hong Kong is one of two Special Administrative Regions of the People's Republic of China , the other being Macau. A city-state situated on China's south coast and enclosed by the Pearl River Delta and South China Sea, it is renowned for its expansive skyline and deep natural harbour...
, Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
, 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...
, the Solomon Islands
Solomon Islands
Solomon Islands is a sovereign state in Oceania, east of Papua New Guinea, consisting of nearly one thousand islands. It covers a land mass of . The capital, Honiara, is located on the island of Guadalcanal...
, Malayasia including Malacca
Malacca
Malacca , dubbed The Historic State or Negeri Bersejarah among locals) is the third smallest Malaysian state, after Perlis and Penang. It is located in the southern region of the Malay Peninsula, on the Straits of Malacca. It borders Negeri Sembilan to the north and the state of Johor to the south...
, Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
, and in 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...
's Northern Territory
Northern Territory
The 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 Queensland
Queensland
Queensland 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...
. It lives on foliage, tree trunks, boulders, and rock walls. Throughout its range, this is the most common species of the genus Portia. Queensland specimens of P. fimbriata live near running water and where there is moderate light, while Northern Territory specimens live in caves where the light varies from rather dark at the back to much brighter around the mouths. Other populations of Portia also live with higher light levels than in Queensland, and some members of these other populations are found in webs exposed to direct sunlight for part of the day. In Queensland
Queensland
Queensland 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...
, P. fimbriata shares its environment with a common prey, the very abundant Jacksonoides queenslandicus, and with large populations of other non-Portia salticids and non-salticid web-building spiders.
Ants prey on P. fimbriata while P. fimbriata does not stalk ants, regarding them as poisonous or very unpleasant. P. fimbriata is also preyed upon by bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s, frog
Frog
Frogs are amphibians in the order Anura , formerly referred to as Salientia . Most frogs are characterized by a short body, webbed digits , protruding eyes and the absence of a tail...
s, and mantis
Mantis
Mantis is the common name of any insect in the order Mantodea, also commonly known as praying mantises. The word itself means "prophet" in Latin and Greek...
es.
It is often difficult to find P. fimbriata in the wild, as its shape and movements are well disguised. The Queensland variety is quite easy to raise, while the Northern Territory variety is quite troublesome to maintain.
Taxonomy
P. fimbriata is one of 17 species in the genus PortiaPortia (genus)
Portia is a genus of jumping spider which feeds on other spiders . They are remarkable for their hunting behaviour which suggests they are capable of learning and problem solving, traits normally attributed to much larger animals....
as of May 2011. Wanless divided the genus Portia into two species group
Species group
A species group is an informal taxonomic rank into which an assemblage of closely related species within a genus are grouped because of their morphological similarities and their identity as a biological unit with a single monophyletic origin.-Use:...
s: the schultzi group, in which males' palps have a fixed tibia
Tibia
The tibia , shinbone, or shankbone is the larger and stronger of the two bones in the leg below the knee in vertebrates , and connects the knee with the ankle bones....
l apophysis
Tubercle
A tubercle is generally a wart-like projection, but it has slightly different meaning depending on which family of plants or animals it is used to refer to....
; and the kenti group, in which the apophysis of each palp in the males has a joint separated by a membrane. The schultzi group includes P. schultzi, P. africana, P. fimbriata, and P. labiata
Portia labiata
Portia labiata is a jumping spider found in Sri Lanka, India, Burma , Malaysia, Singapore, Java, Sumatra and the Philippines. In this medium-sized jumping spider, the front part is orange-brown and the back part is brownish...
.
The species P. fimbriata was originally described by Carl Ludwig Doleschall
Carl Ludwig Doleschall
Carl Ludwig Doleschall was born in Nové Mesto nad Váhom , Slovakia , as the son of the theologian Michael Doleschall, and died in Ambon Island, Moluccas, only 31 years old...
as Salticus fimbriata in 1859. The species has also been named Attus fimbriatus (Hasselt, 1877), Sinis fimbriatus (Thorell, 1878), Linus fimbriatus (Peckham & Peckham, 1886), Boethoportia ocellata (Hogg, 1915), and Portia fimbriata (Wanless, 1978), and the last is now used. According to Jackson and Hallas, P. fimbriata, as currently defined, probably includes two or more distinct species. In particular, Queensland P. fimbriata are probably a distinct species from Sri Lankan P. fimbriata, as matings between the two groups are infertile.
Portia is in the subfamily Spartaeinae
Spartaeinae
The Spartaeinae are a subfamily of the spider family Salticidae . It was established by Fred R. Wanless in 1984 to include the groups Boetheae, Cocaleae, Lineae, Codeteae and Cyrbeae, which in turn were defined by Eugène Simon....
, which is thought to be primitive. Molecular phylogeny
Molecular phylogeny
Molecular phylogenetics is the analysis of hereditary molecular differences, mainly in DNA sequences, to gain information on an organism's evolutionary relationships. The result of a molecular phylogenetic analysis is expressed in a phylogenetic tree...
, a technique that compares the DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
of organisms to reconstruct the tree of life, indicates that Portia is a member of the clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
Spartaeinae, that Spartaeinae is basal (quite similar to the ancestors of all jumping spiders), and that Portia′s closest relatives are the genera Spartaeus
Spartaeus
Spartaeus is a spider genus of the Salticidae family .The genus was renamed from Boethus in 1984 because the name was found to be preoccupied.-Species:* Spartaeus abramovi Logunov & Azarkina, 2008 — Vietnam...
, Phaeacius
Phaeacius
Phaeacius is a spider genus of the family Salticidae , found in sub-tropical China and between India and the Malay Peninsula, including Sri Lanka, Sumatra and the Philippines...
, and Holcolaetis
Holcolaetis
Holcolaetis is a genus of the spider family Salticidae .Like Euryattus and Thiania bhamoensis, these spiders build a flat, densely woven egg sac that is not contiguous with the silk of the nest...
.
External links
- HowStuffWorks Videos "Fooled by Nature: Australian Jumping Spider" – Portia fimbriata catches a web spider
- Salticidae: Diagnostic Drawings Library - Portia fimbriata by Jerzy Proszynski