Portia labiata
Encyclopedia
Portia labiata is a jumping spider
(family
Salticidae) found in Sri Lanka
, India
, Burma (Myanmar), 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 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 essential in P. labiata′s navigation, hunting and mating.
The genus Portia has been called "Eight-legged Cats", as their hunting tactics are as versatile and adaptable as a lion
's. All members of Portia have instinctive hunting tactics for their most common prey, but often can improvise by trial and error
against unfamiliar prey or in unfamiliar situations, and then remember the new approach. While most jumping spiders prey mainly on insects and by active hunting, females of Portia also build webs
to catch prey directly and sometimes join their own webs on to those of web-based spiders. Both females and males prefer web spiders as prey, followed by other jumping spiders, and finally insects. In all cases females are more effective predators than males.
Populations from Los Baños and from Sagada
, both in the Philippines
, have slightly different hunting tactics. In laboratory tests, Los Baños P. labiatas rely more on trial and error than Sagada P. labiatas in finding ways to vibrate the prey's web and thus lure or distract the prey. Around Los Baños the web-building Scytodes
pallida, which preys on jumping spiders, is very abundant, and spits a sticky gum on prey and potential threats. A P. labiata from Los Baños instinctively detours round the back of S. pallida while with plucking the web in a way that makes the prey believe the threat is in front of it. In areas where S. pallida is absent, the local members of P. labiata do not use this combination of deception and detouring for a stab in the back. In a test to explore P. labiata′s ability to solve a novel problem, a miniature lagoon was set up, and the spiders had to find the best way to cross it. Specimens from Sagada, in the mountains, almost always repeated the first option they tried, even when that was unsuccessful. When specimens from Los Baños, beside a lake, were unsuccessful the first time, about three quarters switched to another option.
Adult P. labiatas sometimes uses "propulsive displays", in which an individual threatens a rival of the same sex, and unreceptive females also threaten males in this way. P. labiata females are extremely aggressive to other females, trying to invade and take over each other's webs, which often results in cannibalism
. A test showed that they minimise the risk of confrontations by using silk
draglines as territory
marks. Another test showed that females can recognise the draglines of the most powerful fighters and prefer to move near the draglines of less powerful ones. Females try to kill and eat their mates during or after copulation, while males use tactics to survive copulation, but sometimes females outwit them. Before being mature enough to mate, juvenile females mimic adult females to attract males as prey. When hunting, P. labiata mature females emit olfactory signals that reduce the risk that any other females, males or juveniles of the same species may contend for the same prey.
s in that the usual body segment
s are fused into only two tagmata
, the cephalothorax
and abdomen
. The top of the cephalothorax is covered by a carapace, that of jumping spiders has a distinctive rectangular shape, and that of the genus
Portia slopes gently upward almost to the back, then steeply down. Spiders' abdomens bear appendages that have been modified into spinnerets that extrude silk
from up to six types of silk glands within their abdomen. The cephalothorax and abdomen are joined by a small, cylindrical pedicel
, which allows the abdomen to move while spinning silk
. While most jumping spiders do not build webs to catch prey, they use silk for other purposes, including resting, moult
ing and laying eggs.
Jumping spiders generally have large forelegs and short, powerful back legs. Unlike most arthropods, spiders have no extensor muscles in their limbs and instead extend them by increasing their blood pressure. Jumping spiders can leap up to 50 times their own length by powerfully extending the third or fourth pairs of legs, reaching up to 200 millimetres with the forelimbs extended to grasp the prey.
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 a male spider's are quite large, and are used for displaying and mating.
As in most species of the genus, the bodies of female Portia labiatas are 7 to 10 millimetres long and and their carapaces are 2.8 to 3.8 millimetres long. Males' bodies are 5 to 7.5 millimetres long, with carapaces 2.4 to 3.3 millimetres long. The carapaces of females are orange-brown, slightly lighter around the eyes, where there are sooty streaks and sometimes a violet to green sheen in certain lights. There is a broad white moustache along the bottom of the carapace, and running back from each main eye is ridge that looks like a horn. Females' chelicerae are dark orange-brown and decorated with sparse white hairs, which form bands near the carapaces. The abdomens of females are mottled brown and black, and bear hairs of gold, white and black, and there are tufts consisting of brown hairs tipped with white. The carapaces of males are orange-brown, slightly lighter around the eyes, and have brown-black hairs lying on the surface but with a white wedge-shape stripe from the highest point down to the back, and white bands just above the legs. Males' chelicerae are also orange-brown with brown-black markings. The abdomens of males are brown with lighter markings and with brown-black hairs lying on the surface, and a short band of white hairs. The legs of both sexes are dark brown, with light markings in the femora (the sections of the legs nearest the body). 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 egg
s.
Spiders groom themselves regularly, and more often if wet or dirty. They moisten their fangs, draw the legs one at a time through the fangs, and "comb" the legs with the fangs and palps. The first and fourth pairs of legs are then used to groom other parts of the body, and the only place they appear not to reach is the dorsal surface of the carapace.
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.
When disturbed, most Portias 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.
When isolated on little islands, Portias can enter the water by slowly placing their 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 head 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 Portias 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. labiata 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 millimetres wide at 20 centimetres away, or up to 18 millimetres wide at 30 centimetres away. Jumping spider's main eyes can see from red to ultraviolet
.
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, members of Portia have vision about as acute as the best of the jumping spiders, for example: 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 a Portia 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"). Unlike insects, spiders and other chelicerates do not have antennae
. 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.
safety line to the surface, using the two pairs of back legs to jump on the victim, and finally biting the prey. Most jumping spiders walk throughout the day, so that they maximize their chances of a catch.
Members of the genus Portia
have hunting tactics 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. If a Portia makes a mistake while hunting another spider, it may itself be killed.
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. The web is initially built in about 2 hours, and then gradually made stronger. A Portia often joins her own web on to one of a web-based non-salticid spider. When not joined to another spiders', a P. labiata female's capture web may be suspended from rigid foundations such as boughs and rocks, or from pliant bases such as stems of shrubs.
A web spider's web is an extension of the web spider's senses, informing the spider of vibrations that signal the arrival of prey and predators. If the intruder is another web spider, these vibrations vary widely depending on the new web spider's species, sex and experience. 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 Portias to take web spiders from 10% to 200% of a Portia′s size, and Portias 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: sticky webs adhere to cursorial spiders and to web-builders of non-sticky webs; builders of cribellate
webs have difficulty with non-cribellate webs, and vice versa. Where the web is sparse, a Portia will use "rotary probing", in which it moves a free leg around until it meets a thread. When hunting in another spider's web, a Portia′s slow, choppy movement and the flaps on its legs make it resemble leaf detritus caught in the web and blown in a breeze. P. labiata and some other Portias 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 does not usually take the insect, but waits for up to a day until the insect stops struggling, even if the prey is thoroughly stuck. When an insect 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.
When catching an insect
outside a web, a Portia sometimes lunges and sometimes uses a "pick up", in which it moves its fangs slowly into contact with the prey. In some pick ups, Portia first slowly uses its forelegs to manipulate the prey before biting. P. labiata and P. schultzi also occasionally jump on an insect. However, Portias are not very good at catching moving insects and often ignore them, while some other salticid genera, especially the quick, agile Brettus
and Cyrba
, perform well against small insects.
When a Portia stalks another jumping spider, the prey generally faces the Portia and then either runs away or displays as it does to another member of its own species.
The webs of spiders on which Portias prey sometimes contain dead insects and other arthropods which are uneaten or partly eaten. P. labiata and some other Portias such as P. fimbriata (in Queensland) and P. schultzi sometimes scavenge these corpses if the corpses are not obviously decayed.
A Portia typically takes 3 to 5 minutes to pursuit prey, but some pursuits can take much longer, and in extreme cases close to 10 hours when pursuing a web-based spider.
All Portias 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 Portias steal eggs from empty nests of cursorial spiders.
Portias' venom 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 runs 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 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. If Portia cannot make further contact, all types of prey usually recover, making sluggish movements several minutes after the stabbing but often starting normal movement only after an hour.
Spiders have a narrow gut that can only cope with liquid food, and have two sets of filters to keep solids out. Some spiders pump digestive enzyme
s from the midgut into the prey and then suck the liquified tissues of the prey into the gut, eventually leaving behind the empty husk of the prey. Others grind the prey to pulp using the fangs and the bases of the pedipalp
s, while flooding it with enzymes; in these species the fangs and the bases of the pedipalps form a preoral cavity that holds the food they are processing.
Occasionally a Portia is killed or injured while pursuing prey up to twice Portia′s size. P. labiata is killed in 2.1% of pursuits and injured but not killed in 3.9%, P. schultzi is killed in 1.7% and injured but not killed in 5.3%, and P. fimbriata in Queensland 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 loses 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 Portias are often seen with missing legs or palps, while other salticids in the same habitat are not seen with missing legs or palps.
, P. schultzi
and three regional variants of P. fimbriata
.
A female P. labiata often hangs a capture web from pliant stems and leaves of shrubs and lower branches of trees, rather than from rocks and tree trunks. Males of Portia do not build capture webs.
A female P. labiata more often pursues small jumping spiders and web spiders than larger prey. While it more often catches small jumping spiders than larger ones, it is about equally effective with all sizes of web spiders up to twice P. labiata′s size. A female P. labiata is effective against insects up to twice P. labiata′s size when the insect is stuck in a non-salticid's web, and against insects not in webs and up to P. labiata′s size, while P. labiata seldom pursues or catches a larger insect in the open. A female P. labiata very seldom pursues or catches a larger insect in her own web, and is slightly less effective against smaller insects in P. labiata′s web than in other situations. Males are less efficient in all cases.
A test in 1997 showed that P. labiata from the Philippines
and from Sri Lanka have similar preferences for different types of prey, and that the order of preference is: web spiders; jumping spiders; and insects. These preferences apply to both live prey and motionless lures, and to P. labiata specimens without prey for 7 days ("well-fed") and without prey for 14 days ("starved"). P. labiata 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.
Unlike the Queensland variant of P. frimbriata, P. labiata has no special tactics when hunting other jumping spiders.
P. labiata does not prey on ant
s, but is preyed on by the ants Oecophylla smaragdina
and Odontomachus
sp. (species uncertain).
P. labiata sometimes approaches a translucent nest contain a spider. Usually P. labiata waits faces the prey for up to several hours. Occasionally P. labiata leaps at the prey in the nest, but this is ineffective.
Populations from Los Baños and from Sagada
, both in the Philippines
, have slightly different hunting tactics, and Los Baños has some very dangerous prey spiders. In laboratory tests, Los Baños P. labiatas rely more on trial and error than Sagada P. labiatas in finding ways to vibrate the prey's web and thus lure or distract the prey. Around Los Baños the web-building Scytodes
pallida, which preys on jumping spiders, is very abundant. All members of the genus Scytodes
spit a sticky gum on prey and potential threats, and this can immobilise a Portia long enough for the Scytodes to wrap the Portia in silk and then bite it. Around Los Baños, P. labiata instinctively detours round the back of S. pallida that is not carrying eggs
while with plucking the web in a way that makes S. pallida believe the threat is in front of it. P. labiata prefers to stalk a female S. pallida carrying eggs, as then S. pallida is reluctant to drop the eggs in order to spit, and in this case P. labiata sometimes uses a direct attack. In areas where S. pallida is absent, the local members of P. labiata do not use this combination of plucking other spiders' webs to deceive the prey and detouring for a stab in the back.
A test in 2001 showed that four jumping species take nectar, either by sucking it from the surface of flowers or biting the flowers with their fangs. The spiders fed in cycles of two to four minutes, then groomed, especially their chelicerae, before another cycle. A more formal part of the test showed that 90 juvenile jumping spiders, including P. labiata, generally prefer to suck from blotting soaked with a 30% solution of sugar in water rather than paper soaked with pure 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). Jumping spiders can benefit from amino acids, lipids, vitamin
s and minerals normally found in nectar.
A test in a deliberately artificial environment explored P. labiata′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 small scoop to make waves toward the atoll when the spiders chose the option the testers preferred (leap and then swim for some spiders, and swim only for others), 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. Specimens from Sagada almost always repeated the first option they tried, even when that was unsuccessful. When specimens from Los Baños were unsuccessful the first time, about three quarters switched to the other option, irrespective of whether the first attempt was by leaping and then swimming or by swimming only.
, 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 into reservoirs on his pedipalp
s, which are larger than those of females.
Females of many spider species, including P. labiata, emit volatile pheromone
s into the air, and these generally attract males from a distance. The silk draglines of female jumping spiders also contain pheromones, which stimulate males to court females and may give information about each female's status, for example whether the female is juvenile, subadult or mature.
Pheromones may help to find jumping spiders' nests, which are usually hidden under rocks or in rolled leaves, making them difficult to be seen.
Portias sometimes use "propulsive displays", with which a member threatens a rival of the same species and sex, and unreceptive females also threaten males in this way. A propulsive display is a series of sudden, quick movements including striking, charging, ramming and leaps.
A laboratory test showed how males of P. labiata minimise the risk of meeting each other, by recognising fresh pieces with blotting paper, some containing their own silk draglines and some containing another male's. 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. fimbriata from Queensland showed the same patterns of responses between the sexes.
Among P. labiata and some other Portias, when adults of the same species but opposite sexes recognise each other, they display at 10 to 30 centimetres. Males usually wait for 2 to 15 minutes before starting a display, but sometimes a female starts a display first.
A female P. labiata that sees a male may approach slowly or wait. The male then walks with erect and displaying 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 may cohabit in the female's capture web. Portias usually mate on a web or on a dragline made by the female. P. labiata typically copulates for about 100 seconds, while other genera can take several minutes or even several hours.
Females of P. labiata and P. schultzi
try to kill and eat their mates during or after copulation, by twisting and lunging. The males wait until the females have hunched their legs, making this attack less likely. Males also try to abseil from a silk thread to approach from above, but females may manoeuvre to get the higher position. If the female moves at all, the male leaps and runs away.
Before being mature enough to mate, females of P. labiata and also P. schultzi mimic adult females to attract males as prey.
P. labiata females are extremely aggressive to other females, trying to invade and take over each other's webs, which often results in cannibalism
. A laboratory test showed how they minimise the risk of meeting each other, by recognising pieces with blotting paper containing their own silk draglines and pieces contain other P. labiata females' draglines. If obstacles make it impossible to see whether the other is physically present, she avoids blotting paper containing the other's draglines, but moves with no constraint if she can see that the other female is not around. Draglines seem to act as territory
marks, much as many mammals identify conspecifics by scent marking. P. labiata females also avoid rival females of higher fighting ability and spend more time around less powerful fighters. A laboratory test collected samples of the draglines of equal-sized females and then pitted some of them in contests. Other females avoided the draglines of the victors, and spent the majority of their time on draglines of the losers. Similar tests showed that females of P. fimbriata
from Australia and P. schultzi
from Kenya do not avoid draglines of a powerful fighter.
In P. labiata 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 violent and embraces in P. labiata typically take 20 to 60 seconds. These occasionally include grappling that sometimes breaks a leg, but more usually one female lunges at the other. Sometimes one knocks the other on her back and the other may be killed and eaten if she does not right herself quickly and run way. If the loser has a nest, the winner takes over and eats any eggs there.
When hunting, mature females of P. labiata, P. africana, P. fimbriata 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.
P. labiata usually lays 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.
Portia females have never been seen eating their own eggs, but in nature females with eggs of their own have been seen eating eggs of other females of the same species. In a test, P. labiata females did not eat their eggs if the testers put them in other female's nests, showing that the test females could identify their own eggs, possibly by chemical means. When the test females and their eggs were restored to their own nests and other females' eggs were also placed in the same nest, the test females ate neither their own eggs nor the "foreign" ones. In nature a female is unlikely to find foreign eggs in her nest, and it might be safest for females to avoid any eggs in their own nests.
For moult
ing, all Portias 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. Portias spin a similar temporary web for resting.
, India
, Burma (Myanmar), Malaysia, Singapore
, Java
, Sumatra
and the Philippines
.
The populations of P. labiata in Los Baños and in Sagada
, both in the Philippines, have different environments: Los Baños is a low-lying tropical rainforest
where there are many species of spiders, some of which are especially dangerous to P. labiata; and Sagada is at higher altitude, with pine-forest and fewer species of spiders, none of which are as dangerous to P. labiata. The Los Baños variant has a slightly wider repertoire of tactics.
In the Philippines, P. labiata does not prey on ant
s, but is preyed on by the ants Oecophylla smaragdina
and Odontomachus
sp. (species uncertain), and a solitary Odontomachus has been seen attacking a P. labiata. In a test the ant Diacamma
vagans usually killed single-handed a P. labiata.
as of May 2011. This species has been named Sinis fimbriatus (Hasselt, 1882; misidentification), Linus labiatus (Thorell, 1887), Linus dentipalpis (Thorell, 1890), Erasinus dentipalpis (Thorell, 1892), Erasinus labiatus (Simon, 1903) and Portia labiata (Wanless, 1978), and the last name has been used since then.
Portia is in the subfamily Spartaeinae
, which is thought to be primitive. Molecular phylogeny
, a technique that compares the DNA
of organisms to reconstruct the tree of life, indicates that Portia is a member of the clade
Spartaeinae, that Spartaeinae is basal (quite similar to the ancestors of all jumping spiders), that Portia′s closest relative is the genus Spartaeus
, and that the next closest are Phaeacius
and Holcolaetis
.
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 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...
, India
India
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...
, Burma (Myanmar), Malaysia, Singapore
Singapore
Singapore , officially the Republic of Singapore, is a Southeast Asian city-state off the southern tip of the Malay Peninsula, north of the equator. An island country made up of 63 islands, it is separated from Malaysia by the Straits of Johor to its north and from Indonesia's Riau Islands by the...
, Java
Java
Java is an island of Indonesia. With a population of 135 million , it is the world's most populous island, and one of the most densely populated regions in the world. It is home to 60% of Indonesia's population. The Indonesian capital city, Jakarta, is in west Java...
, Sumatra
Sumatra
Sumatra is an island in western Indonesia, westernmost of the Sunda Islands. It is the largest island entirely in Indonesia , and the sixth largest island in the world at 473,481 km2 with a population of 50,365,538...
and the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
. In this medium-sized jumping spider, the front part is orange-brown and the back part is brownish. The conspicuous main eyes provide vision more acute than a cat
Cat
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 during the day and 10 times more acute than a dragonfly's
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...
, and this is essential in P. labiata′s navigation, hunting and mating.
The genus Portia has been called "Eight-legged Cats", as their hunting tactics are as versatile and adaptable as a lion
Lion
The lion is one of the four big cats in the genus Panthera, and a member of the family Felidae. With some males exceeding 250 kg in weight, it is the second-largest living cat after the tiger...
's. All members of Portia have instinctive hunting tactics for their most common prey, but often 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. While most jumping spiders prey mainly on insects and by active hunting, females of Portia also build webs
Spider web
A spider web, spiderweb, spider's web or cobweb is a device built by a spider out of proteinaceous spider silk extruded from its spinnerets....
to catch prey directly and sometimes join their own webs on to those of web-based spiders. Both females and males prefer web spiders as prey, followed by other jumping spiders, and finally insects. In all cases females are more effective predators than males.
Populations from Los Baños and from Sagada
Sagada, Mountain Province
Sagada is a 5th class municipality in the province of Mountain Province, Philippines. According to the latest census, it has a population of 10,930 people in 2,158 households....
, both in the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
, have slightly different hunting tactics. In laboratory tests, Los Baños P. labiatas rely more on trial and error than Sagada P. labiatas in finding ways to vibrate the prey's web and thus lure or distract the prey. Around Los Baños the web-building Scytodes
Scytodes
Scytodes is a genus of spitting spider that occurs all around the world. The best known species is Scytodes thoracica which has a holarctic distribution....
pallida, which preys on jumping spiders, is very abundant, and spits a sticky gum on prey and potential threats. A P. labiata from Los Baños instinctively detours round the back of S. pallida while with plucking the web in a way that makes the prey believe the threat is in front of it. In areas where S. pallida is absent, the local members of P. labiata do not use this combination of deception and detouring for a stab in the back. In a test to explore P. labiata′s ability to solve a novel problem, a miniature lagoon was set up, and the spiders had to find the best way to cross it. Specimens from Sagada, in the mountains, almost always repeated the first option they tried, even when that was unsuccessful. When specimens from Los Baños, beside a lake, were unsuccessful the first time, about three quarters switched to another option.
Adult P. labiatas sometimes uses "propulsive displays", in which an individual threatens a rival of the same sex, and unreceptive females also threaten males in this way. P. labiata females are extremely aggressive to other females, trying to invade and take over each other's webs, which often results in cannibalism
Cannibalism
Cannibalism is the act or practice of humans eating the flesh of other human beings. It is also called anthropophagy...
. A test showed that they minimise the risk of confrontations by using silk
Spider silk
Spider silk is a protein fiber spun by spiders. Spiders use their silk to make webs or other structures, which function as nets to catch other animals, or as nests or cocoons for protection for their offspring...
draglines as territory
Territory (animal)
In ethology the term territory refers to any sociographical area that an animal of a particular species consistently defends against conspecifics...
marks. Another test showed that females can recognise the draglines of the most powerful fighters and prefer to move near the draglines of less powerful ones. Females try to kill and eat their mates during or after copulation, while males use tactics to survive copulation, but sometimes females outwit them. Before being mature enough to mate, juvenile females mimic adult females to attract males as prey. When hunting, P. labiata mature females emit olfactory signals that reduce the risk that any other females, males or juveniles of the same species may contend for the same prey.
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...
. The top of the cephalothorax is covered by a carapace, that of jumping spiders has a distinctive rectangular shape, and that of 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 slopes gently upward almost to the back, then steeply down. Spiders' abdomens bear appendages that have been modified into spinnerets that extrude silk
Spider silk
Spider silk is a protein fiber spun by spiders. Spiders use their silk to make webs or other structures, which function as nets to catch other animals, or as nests or cocoons for protection for their offspring...
from up to six types of silk glands within their abdomen. The cephalothorax and abdomen are joined by a small, cylindrical 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
Spider silk
Spider silk is a protein fiber spun by spiders. Spiders use their silk to make webs or other structures, which function as nets to catch other animals, or as nests or cocoons for protection for their offspring...
. While most jumping spiders do not build webs to catch prey, they use silk for other purposes, including resting, 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 and laying eggs.
Jumping spiders generally have large forelegs and short, powerful back legs. Unlike most arthropods, spiders have no extensor muscles in their limbs and instead extend them by increasing their blood pressure. Jumping spiders can leap up to 50 times their own length by powerfully extending the third or fourth pairs of legs, reaching up to 200 millimetres with the forelimbs extended to grasp the prey.
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 a male spider's are quite large, and are used for displaying and mating.
As in most species of the genus, the bodies of female Portia labiatas are 7 to 10 millimetres long and and their carapaces are 2.8 to 3.8 millimetres long. Males' bodies are 5 to 7.5 millimetres long, with carapaces 2.4 to 3.3 millimetres long. The carapaces of females are orange-brown, slightly lighter around the eyes, where there are sooty streaks and sometimes a violet to green sheen in certain lights. There is a broad white moustache along the bottom of the carapace, and running back from each main eye is ridge that looks like a horn. Females' chelicerae are dark orange-brown and decorated with sparse white hairs, which form bands near the carapaces. The abdomens of females are mottled brown and black, and bear hairs of gold, white and black, and there are tufts consisting of brown hairs tipped with white. The carapaces of males are orange-brown, slightly lighter around the eyes, and have brown-black hairs lying on the surface but with a white wedge-shape stripe from the highest point down to the back, and white bands just above the legs. Males' chelicerae are also orange-brown with brown-black markings. The abdomens of males are brown with lighter markings and with brown-black hairs lying on the surface, and a short band of white hairs. The legs of both sexes are dark brown, with light markings in the femora (the sections of the legs nearest the body). 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 egg
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...
s.
Spiders groom themselves regularly, and more often if wet or dirty. They moisten their fangs, draw the legs one at a time through the fangs, and "comb" the legs with the fangs and palps. The first and fourth pairs of legs are then used to groom other parts of the body, and the only place they appear not to reach is the dorsal surface of the carapace.
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 chelicerae ("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 piece of detritus.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.
When disturbed, most Portias 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.
When isolated on little islands, Portias can enter the water by slowly placing their 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 head 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 Portias 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. labiata 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 millimetres wide at 20 centimetres away, or up to 18 millimetres wide at 30 centimetres away. Jumping spider's main eyes can see from red to ultraviolet
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
.
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, members of Portia have vision about as acute as the best of the jumping spiders, for example: 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 a Portia 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"). Unlike insects, spiders and other chelicerates do not have antennae
Antenna (biology)
Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....
. 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.
Tactics used by most jumping spiders and by most of genus Portia
Almost all jumping spiders are predators, mostly preying on insects, on other spiders, and on other arthropods. The most common procedure is sighting the prey, stalking, fastening a silkSpider silk
Spider silk is a protein fiber spun by spiders. Spiders use their silk to make webs or other structures, which function as nets to catch other animals, or as nests or cocoons for protection for their offspring...
safety line to the surface, using the two pairs of back legs to jump on the victim, and finally biting the prey. Most jumping spiders walk throughout the day, so that they maximize their chances of a catch.
Members 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 hunting tactics 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. If a Portia makes a mistake while hunting another spider, it may itself be killed.
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. The web is initially built in about 2 hours, and then gradually made stronger. A Portia often joins her own web on to one of a web-based non-salticid spider. When not joined to another spiders', a P. labiata female's capture web may be suspended from rigid foundations such as boughs and rocks, or from pliant bases such as stems of shrubs.
A web spider's web is an extension of the web spider's senses, informing the spider of vibrations that signal the arrival of prey and predators. If the intruder is another web spider, these vibrations vary widely depending on the new web spider's species, sex and experience. 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 Portias to take web spiders from 10% to 200% of a Portia′s size, and Portias 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: sticky webs adhere to cursorial spiders and to web-builders of non-sticky webs; builders of cribellate
Cribellum
The cribellum is a silk spinning organ found in certain spiders. Unlike normal spinnerets, the cribellum consists of one or more plates covered in thousands of tiny spigots. These spigots produce extremely fine fibers which are combed out by the spider's calamistrum, producing silk with a wooly...
webs have difficulty with non-cribellate webs, and vice versa. Where the web is sparse, a Portia will use "rotary probing", in which it moves a free leg around until it meets a thread. When hunting in another spider's web, a Portia′s slow, choppy movement and the flaps on its legs make it resemble leaf detritus caught in the web and blown in a breeze. P. labiata and some other Portias 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 does not usually take the insect, but waits for up to a day until the insect stops struggling, even if the prey is thoroughly stuck. When an insect 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
Portia fimbriata
Portia fimbriata, sometimes called the fringed jumping spider, is a jumping spider 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...
, 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.
When catching an 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...
outside a web, a Portia sometimes lunges and sometimes uses a "pick up", in which it moves its fangs slowly into contact with the prey. In some pick ups, Portia first slowly uses its forelegs to manipulate the prey before biting. P. labiata and P. schultzi also occasionally jump on an insect. However, Portias are not very good at catching moving insects and often ignore them, while some other salticid genera, especially the quick, agile Brettus
Brettus
Brettus is a genus of jumping spiders. Its name comes from the Greek, βρεττυς, meaning one who does not fight. Its six described species are found in southern Asia from India to China and Sulawesi, with a single species endemic to Madagascar....
and Cyrba
Cyrba
Cyrba is a genus of the spider family Salticidae .-Description:Cyrba spiders are small to medium size spiders that are usually brightly colored. Their cephalothorax is long and moderately high. The eyes are lateral. The abdomen is long with bright colorful patterns. Their legs are thin and slender...
, perform well against small insects.
When a Portia stalks another jumping spider, the prey generally faces the Portia and then either runs away or displays as it does to another member of its own species.
The webs of spiders on which Portias prey sometimes contain dead insects and other arthropods which are uneaten or partly eaten. P. labiata and some other Portias such as P. fimbriata (in Queensland) and P. schultzi sometimes scavenge these corpses if the corpses are not obviously decayed.
A Portia typically takes 3 to 5 minutes to pursuit prey, but some pursuits can take much longer, and in extreme cases close to 10 hours when pursuing a web-based spider.
All Portias 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 Portias steal eggs from empty nests of cursorial spiders.
Portias' venom 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 runs 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 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. If Portia cannot make further contact, all types of prey usually recover, making sluggish movements several minutes after the stabbing but often starting normal movement only after an hour.
Spiders have a narrow gut that can only cope with liquid food, and have two sets of filters to keep solids out. Some spiders pump digestive enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
s from the midgut into the prey and then suck the liquified tissues of the prey into the gut, eventually leaving behind the empty husk of the prey. Others grind the prey to pulp using the fangs and the bases of the 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, while flooding it with enzymes; in these species the fangs and the bases of the pedipalps form a preoral cavity that holds the food they are processing.
Occasionally a Portia is killed or injured while pursuing prey up to twice Portia′s size. P. labiata is killed in 2.1% of pursuits and injured but not killed in 3.9%, P. schultzi is killed in 1.7% and injured but not killed in 5.3%, and P. fimbriata in Queensland 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 loses 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 Portias are often seen with missing legs or palps, while other salticids in the same habitat are not seen with missing legs or palps.
Tactics used by Portia labiata
All performance statistics summarise result of tests in a laboratory, using captive specimens. The following table shows the hunting performance of adult females. In addition to P. labiata, the table shows for comparison the hunting performances of P. africanaPortia 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...
, 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...
and three regional variants of P. fimbriata
Portia fimbriata
Portia fimbriata, sometimes called the fringed jumping spider, is a jumping spider 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...
.
| Prey | | Performance | P. labiata | P. africana | P. schultzi | P. fimbriata (Q) | P. fimbriata (NT) | P. fimbriata (SL) |
|---|---|---|---|---|---|---|---|
| Salticid | Tendency to pursue prey | 63% | 77% | 58% | 87% | 50% | 94% |
| Efficiency in capturing prey | 40% | 29% | 36% | 93% | 10% | 45% | |
| Web-building spider |
Tendency to pursue prey | 83% | 74% | 84% | 91% | 94% | 64% |
| Efficiency in capturing prey | 79% | 65% | 72% | 92% | 81% | 83% | |
| Insect | Tendency to pursue prey | 35% | 48% | 52% | 27% | 30% | 43% |
| Efficiency in capturing prey | 71% | 67% | 69% | 41% | 83% | 78% |
A female P. labiata often hangs a capture web from pliant stems and leaves of shrubs and lower branches of trees, rather than from rocks and tree trunks. Males of Portia do not build capture webs.
A female P. labiata more often pursues small jumping spiders and web spiders than larger prey. While it more often catches small jumping spiders than larger ones, it is about equally effective with all sizes of web spiders up to twice P. labiata′s size. A female P. labiata is effective against insects up to twice P. labiata′s size when the insect is stuck in a non-salticid's web, and against insects not in webs and up to P. labiata′s size, while P. labiata seldom pursues or catches a larger insect in the open. A female P. labiata very seldom pursues or catches a larger insect in her own web, and is slightly less effective against smaller insects in P. labiata′s web than in other situations. Males are less efficient in all cases.
A test in 1997 showed that P. labiata from the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
and from Sri Lanka have similar preferences for different types of prey, and that the order of preference is: web spiders; jumping spiders; and insects. These preferences apply to both live prey and motionless lures, and to P. labiata specimens without prey for 7 days ("well-fed") and without prey for 14 days ("starved"). P. labiata 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.
Unlike the Queensland variant of P. frimbriata, P. labiata has no special tactics when hunting other jumping spiders.
P. labiata does not prey on 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...
s, but is preyed on by the ants Oecophylla smaragdina
Oecophylla smaragdina
Oecophylla smaragdina is a species of arboreal ant found in Asia and Australia. They make nests in trees made of leaves stitched together using the silk produced by their larvae.Weaver ants may be red or green...
and Odontomachus
Odontomachus
Odontomachus is a genus of carnivorous ants found in the tropics and subtropics throughout the world.-Overview:Commonly known as trap-jaw ants, species in Odontomachus have a pair of large, straight mandibles capable of opening 180 degrees...
sp. (species uncertain).
P. labiata sometimes approaches a translucent nest contain a spider. Usually P. labiata waits faces the prey for up to several hours. Occasionally P. labiata leaps at the prey in the nest, but this is ineffective.
Populations from Los Baños and from Sagada
Sagada, Mountain Province
Sagada is a 5th class municipality in the province of Mountain Province, Philippines. According to the latest census, it has a population of 10,930 people in 2,158 households....
, both in the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
, have slightly different hunting tactics, and Los Baños has some very dangerous prey spiders. In laboratory tests, Los Baños P. labiatas rely more on trial and error than Sagada P. labiatas in finding ways to vibrate the prey's web and thus lure or distract the prey. Around Los Baños the web-building Scytodes
Scytodes
Scytodes is a genus of spitting spider that occurs all around the world. The best known species is Scytodes thoracica which has a holarctic distribution....
pallida, which preys on jumping spiders, is very abundant. All members of the genus Scytodes
Scytodes
Scytodes is a genus of spitting spider that occurs all around the world. The best known species is Scytodes thoracica which has a holarctic distribution....
spit a sticky gum on prey and potential threats, and this can immobilise a Portia long enough for the Scytodes to wrap the Portia in silk and then bite it. Around Los Baños, P. labiata instinctively detours round the back of S. pallida that is not carrying 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...
while with plucking the web in a way that makes S. pallida believe the threat is in front of it. P. labiata prefers to stalk a female S. pallida carrying eggs, as then S. pallida is reluctant to drop the eggs in order to spit, and in this case P. labiata sometimes uses a direct attack. In areas where S. pallida is absent, the local members of P. labiata do not use this combination of plucking other spiders' webs to deceive the prey and detouring for a stab in the back.
A test in 2001 showed that four jumping species take nectar, either by sucking it from the surface of flowers or biting the flowers with their fangs. The spiders fed in cycles of two to four minutes, then groomed, especially their chelicerae, before another cycle. A more formal part of the test showed that 90 juvenile jumping spiders, including P. labiata, generally prefer to suck from blotting soaked with a 30% solution of sugar in water rather than paper soaked with pure 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). Jumping spiders can 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.
A test in a deliberately artificial environment explored P. labiata′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 small scoop to make waves toward the atoll when the spiders chose the option the testers preferred (leap and then swim for some spiders, and swim only for others), 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. Specimens from Sagada almost always repeated the first option they tried, even when that was unsuccessful. When specimens from Los Baños were unsuccessful the first time, about three quarters switched to the other option, irrespective of whether the first attempt was by leaping and then swimming or by swimming only.
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 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.
Females of many spider species, including P. labiata, emit volatile pheromone
Pheromone
A pheromone is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting outside the body of the secreting individual to impact the behavior of the receiving individual...
s into the air, and these generally attract males from a distance. The silk draglines of female jumping spiders also contain pheromones, which stimulate males to court females and may give information about each female's status, for example whether the female is juvenile, subadult or mature.
Pheromones may help to find jumping spiders' nests, which are usually hidden under rocks or in rolled leaves, making them difficult to be seen.
Portias sometimes use "propulsive displays", with which a member threatens a rival of the same species and sex, and unreceptive females also threaten males in this way. A propulsive display is a series of sudden, quick movements including striking, charging, ramming and leaps.
A laboratory test showed how males of P. labiata minimise the risk of meeting each other, by recognising fresh pieces with blotting paper, some containing their own silk draglines and some containing another male's. 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. fimbriata from Queensland showed the same patterns of responses between the sexes.
Among P. labiata and some other Portias, when adults of the same species but opposite sexes recognise each other, they display at 10 to 30 centimetres. Males usually wait for 2 to 15 minutes before starting a display, but sometimes a female starts a display first.
A female P. labiata that sees a male may approach slowly or wait. The male then walks with erect and displaying 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 may cohabit in the female's capture web. Portias usually mate on a web or on a dragline made by the female. P. labiata typically copulates for about 100 seconds, while other genera can take several minutes or even several hours.
Females of P. labiata and 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...
try to kill and eat their mates during or after copulation, by twisting and lunging. The males wait until the females have hunched their legs, making this attack less likely. Males also try to abseil from a silk thread to approach from above, but females may manoeuvre to get the higher position. If the female moves at all, the male leaps and runs away.
Before being mature enough to mate, females of P. labiata and also P. schultzi mimic adult females to attract males as prey.
P. labiata females are extremely aggressive to other females, trying to invade and take over each other's webs, which often results in cannibalism
Cannibalism (zoology)
In zoology, cannibalism is the act of one individual of a species consuming all or part of another individual of the same species as food. Cannibalism is a common ecological interaction in the animal kingdom and has been recorded for more than 1500 species...
. A laboratory test showed how they minimise the risk of meeting each other, by recognising pieces with blotting paper containing their own silk draglines and pieces contain other P. labiata females' draglines. If obstacles make it impossible to see whether the other is physically present, she avoids blotting paper containing the other's draglines, but moves with no constraint if she can see that the other female is not around. Draglines seem to act as territory
Territory (animal)
In ethology the term territory refers to any sociographical area that an animal of a particular species consistently defends against conspecifics...
marks, much as many mammals identify conspecifics by scent marking. P. labiata females also avoid rival females of higher fighting ability and spend more time around less powerful fighters. A laboratory test collected samples of the draglines of equal-sized females and then pitted some of them in contests. Other females avoided the draglines of the victors, and spent the majority of their time on draglines of the losers. Similar tests showed that females of P. fimbriata
Portia fimbriata
Portia fimbriata, sometimes called the fringed jumping spider, is a jumping spider 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...
from Australia and 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...
from Kenya do not avoid draglines of a powerful fighter.
In P. labiata 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 violent and embraces in P. labiata typically take 20 to 60 seconds. These occasionally include grappling that sometimes breaks a leg, but more usually one female lunges at the other. Sometimes one knocks the other on her back and the other may be killed and eaten if she does not right herself quickly and run way. If the loser has a nest, the winner takes over and eats any eggs there.
When hunting, mature females of P. labiata, P. africana, P. fimbriata 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.
P. labiata usually lays 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.
Portia females have never been seen eating their own eggs, but in nature females with eggs of their own have been seen eating eggs of other females of the same species. In a test, P. labiata females did not eat their eggs if the testers put them in other female's nests, showing that the test females could identify their own eggs, possibly by chemical means. When the test females and their eggs were restored to their own nests and other females' eggs were also placed in the same nest, the test females ate neither their own eggs nor the "foreign" ones. In nature a female is unlikely to find foreign eggs in her nest, and it might be safest for females to avoid any eggs in their own nests.
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 Portias 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. Portias spin a similar temporary web for resting.
Ecology
P. labiata is found in Sri LankaSri 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...
, India
India
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...
, Burma (Myanmar), Malaysia, Singapore
Singapore
Singapore , officially the Republic of Singapore, is a Southeast Asian city-state off the southern tip of the Malay Peninsula, north of the equator. An island country made up of 63 islands, it is separated from Malaysia by the Straits of Johor to its north and from Indonesia's Riau Islands by the...
, Java
Java
Java is an island of Indonesia. With a population of 135 million , it is the world's most populous island, and one of the most densely populated regions in the world. It is home to 60% of Indonesia's population. The Indonesian capital city, Jakarta, is in west Java...
, Sumatra
Sumatra
Sumatra is an island in western Indonesia, westernmost of the Sunda Islands. It is the largest island entirely in Indonesia , and the sixth largest island in the world at 473,481 km2 with a population of 50,365,538...
and the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
.
The populations of P. labiata in Los Baños and in Sagada
Sagada, Mountain Province
Sagada is a 5th class municipality in the province of Mountain Province, Philippines. According to the latest census, it has a population of 10,930 people in 2,158 households....
, both in the Philippines, have different environments: Los Baños is a low-lying tropical rainforest
Rainforest
Rainforests are forests characterized by high rainfall, with definitions based on a minimum normal annual rainfall of 1750-2000 mm...
where there are many species of spiders, some of which are especially dangerous to P. labiata; and Sagada is at higher altitude, with pine-forest and fewer species of spiders, none of which are as dangerous to P. labiata. The Los Baños variant has a slightly wider repertoire of tactics.
In the Philippines, P. labiata does not prey on 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...
s, but is preyed on by the ants Oecophylla smaragdina
Oecophylla smaragdina
Oecophylla smaragdina is a species of arboreal ant found in Asia and Australia. They make nests in trees made of leaves stitched together using the silk produced by their larvae.Weaver ants may be red or green...
and Odontomachus
Odontomachus
Odontomachus is a genus of carnivorous ants found in the tropics and subtropics throughout the world.-Overview:Commonly known as trap-jaw ants, species in Odontomachus have a pair of large, straight mandibles capable of opening 180 degrees...
sp. (species uncertain), and a solitary Odontomachus has been seen attacking a P. labiata. In a test the ant Diacamma
Diacamma
Diacamma is a genus of queenless ants belonging to the subfamily Ponerinae. It is distributed from India to Australia and contains about 50 species.Diacamma species of India include:* Diacamma assamense Forel, 1897...
vagans usually killed single-handed a P. labiata.
Taxonomy
P. labiata 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. This species has been named Sinis fimbriatus (Hasselt, 1882; misidentification), Linus labiatus (Thorell, 1887), Linus dentipalpis (Thorell, 1890), Erasinus dentipalpis (Thorell, 1892), Erasinus labiatus (Simon, 1903) and Portia labiata (Wanless, 1978), and the last name has been used since then.
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), that Portia′s closest relative is the genus 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...
, and that the next closest are 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...
.