User:Philcha/Sandbox/Portia (spider) 2

Range
Species in the genus Portia live the Old World, from Sierra Leone in the west to Australia in the east, and south to South Africa, and in India, China, Taiwan and Vietnam.

As of mid-2011, the Museum and Institute of Zoology in Warsaw acknowledges 18 species of Portia.

Some well-researched species live in forests, which may be inland or near bodies of water. However, one subspecies inhabits the mouths and interiors of caves, and another species lives in patches of shrubs around savannah.

Body structure and appearance
Spiders are chelicerates, which differ from other arthropods in that the usual body segments 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, and either side has a steep slope with a slight "devil's horn" ridge along the top.

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 pedipalps ("palps" for short), and those of male spiders are quite large and are used for displaying and mating.

In many Portia species, females bodies grow to about 10 millimetres long, while males can reach about 8 millimetres. However, females of P. schultzi grow to about 7 millimetres long, while males do not exceed 6 millimetres.

Where described, the carapacs of both sexes of all species are orange-brown, but each species and sex has a different decoration of patches and hairs. The abdomens vary by species and sex: females' ranges from light yellow to mottled brown and black, while males' ranges from yellow-orange to brown. The body is also decorated with smooth hairs, which vary by species and sex. The legs have spikes on the upper parts and smooth hairs on the lower.

Movement
When not hunting for prey or a mate, Portias 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, most 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. P. schultzi uses what Forster and Murphy (1986) call a "lolloping" gait, flexing and stretching the legs. They suggest that the long legs are advantageous for moving through webs, and that lolloping enables P. schultzi to use the long legs while keeping the body near the surface.

Like many species of spider, a Portia lays a continuous dragline of silk as it moves, and from time to time anchors the dragline to a surface with a spot of sticky silk. This allows the spider to return to the surface if the animal is dislodged. A spider about to jump first lays a sticky silk anchor, and then lays out a dragline as it flies. Unlike those of most jumping spiders, P. schultzi′s draglines stick to each other and, when a P. schultzi has laid a few lines across a gap, it uses these as walkways and reinforces them with additional silk as it moves.

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.

Senses
Jumping spiders have significantly better vision than other spiders,, much more acute than that of other animals of similar size, , and clearer in daylight than a cat's and 10 times more acute than a dragonfly's. A jumping spider has eight eyes, of which the two large ones in the center-and-front position (the anterior-median eyes, also called "principal eyes") are housed in tubes in the head and  provide 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, Portias 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 birds, frogs and mantises, which a Portia often cannot identify because of the other predator's size.

Spiders, like other arthropods, have protruding through their cuticle ("skin") sensors, often modified setae (bristles), for smell, taste, touch and vibration. 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.

Chemoreception is also important to Portia (Peckham and Peckham, 1887; Heil, 1936); pheromones left by conspecifics influence courtship (Pollard et al., 1987). Furthermore, Portia can discriminate between itself and conspecifics, identify conspecifics as familiar, and determine the sex of conspecifics based on chemical cues imbedded in their silk (Willey and Jackson, 1993; R. J. Clark and Jackson, 1994a,b, 1995a,b). Air and substrate-borne chemical cues are also used to detect commonly encountered prey (Jackson et al., 2002).

General hunting methods
Members of the genus  Portia have hunting tactics as versatile and adaptable as a lion's. Most species of jumping spiders appear to be cursorial, hunt insects, and do not use webs for this. However, the African, Asian and Australasian genus Portia prefers to hunt other spiders, often invading the victims' webs. Some Portias, including P. africana, also efficiently hunt jumping spiders.

A web-based spider has poor spatial appreciation and gets much of its information from reading tensions and movement in her web. P. africana, P. fimbraba and P. labiata can use its eight legs and two palps at one time to pluck another spider's web with a virtually unlimited range of movements, using in a trial and error  method, until it finds and repeats a set of movements that either lures the prey out into the open or calms the prey while the Portia walks slowly close enough to bite the victim. If the prey stops being controlled by the sequence, the Portia tries new combinations until one works, and then repeats the new sequence. While such hunting shows use of least short-term memory, as of 2011 researchers do not know how long a Portia can retain such memories nor whether a Portia may use different trial and error starts for some prey species.

Such tactics enable Portia species to take web-based 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. africana and some other Portia species use breezes and other disturbances as "smokescreens" in which these predators can approach web-based 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".

Females of Portia also build webs to catch prey directly. , and those of P. africana are usually attached to rigid surfaces such as rocks and tree trunks. 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.

Portias can 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.

When hunting, mature females of 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.

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.

Species' hunting and feeding variations
Previous studies have shown that species of the genus Portia' prefer to prey on other spiders rather than on insects, and survive and grow better when feeding on spiders than on insects. However, tests show that, if  P. quei is prevented from feeding on spiders, it can thrive better exclusively on the right type of fruit flies than on spiders, provided that the prey is from a high-protein strain rather than a high-lipid one.

While other Portias live and hunt as individuals, P. africana forms large populations both in savanna areas and in the dense "cities" which social jumping spiders build in vegetation near the shoreline of a lake. In the savanna, groups of P. africana, generally consisting of small juveniles, delay the prey until one juvenile bites the victim, and sometimes the juvenile shares the food with other. Around the shoreline, P. africana hunts in the miniature cities, two species of assassin bug prey on P. africana, and one assassin bug also preys on the other.

When hunting, mature females of 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.

Portia fimbriata has four regional variants, and the three whose behaviour has been studied show clear differences in hunting preferences and performances.

In the Philippines, the lakeside populations of  Portia labiata shows greater adaptability than populations highland in hunting the dangerous spitting spider Scytodes pallida, and in crossing water. A laboratory test showed that P.labiata will suck sugar from paper, and the researchers suggested that, in the wild, nectar may be a frequent, convenient way to get some nutrients, as it would avoid the risks and costs of hunting.

Reproduction and lifecycle
Females of many spider species, including P. labiata, emit volatile pheromones 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 (too young to copulate), subadult (will copulate after the next moult) or mature (ready to copulate). Pheromones may help to find jumping spiders' nests, which are usually hidden under rocks or in rolled leaves, making them difficult to be seen.

Laboratory tests showed how males of P. fimbriata (from Queensland) and P. labiata minimise the risk of meeting rivals of the same species, by recognising fresh pieces with blotting paper, some containing their own silk draglines and some containing another male's. The males were also attracted by fresh blotting paper containing draglines of their own species' females, 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.

A matures or sub-adult (one moult from maturity) female P. labiata that is preparing to mate starts a short trial of strengh with an advancing male. If the pair continues, the male will copulate if the female is mature or, if the female is sub-adult, the male will cohabit in the female's capture web and copulate when the female moults.

Females of P. labiata and P. schultzi try to kill and eat their mates during or after copulation Femalesc that are too young will mimic adult females to attract males as prey. However, females of P. fimbriata do not kill their mates during or after copulation.

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.

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.

In laboratory tests, Portia species mate with other Portia species, but the females then produce no eggs.

P. fimbriata Queensland and from Sri Lankan may be distinct species, as matings between the two groups are infertile.

Family tree
Simplified version of Maddison & Needham's summary cladogram Traditioal taxonomy concenrated on separate families and subfamilies of jumping spiders, which were often definited by arbitrary criteria chosed by the researchs. In 1901-1903, Simon was the first to arrange jumping spiders them into larger groupings, based on sets of characteristics.

In 1982 Jackson and Blest suggested a hypothesis that the ancestors of jumping spiders evolved from web-building spiders (which have poor vision), then started to invade other spiders' webs and eat the victims, and then developed acute vision.

The great majority of spiders have very poor vision, and rely on their extremely sensitive sense for vibrations over their webs to catch prey and avoid threats. While a few other spiders have moderate vision, only Salticidae (jumping spider) have the four-layer retinae

Wanless (1978) noted that members of Portia have full functioal middle secondary eyes, while most jumping spiders, called Salticoida, have only vestigial middle secondary eyes which have no known function.

Wanless (1978) noted that members of Portia have full functioal middle secondary eyes, while most jumping spiders have only vestigial middle secondary eyes which have no known function. In 1982 Jackson and Blest suggested a hypothesis that the ancestors of jumping spiders evolved from web-building spiders (which have poor vision), then started to invade other spiders' webs and eat the victims, and then developed acute vision.

Jumping spiders (family Salticidae) have vision more acute in daylight than a cat's and 10 times more acute than a dragonfly's. The main eyes, in the front-and-centre position, are housed in tubes that are fix at the front and free at the back, and see in three colours, ... !! Phylogenetic reconstruction

opsin (a protein) which helps an eyes to respond to light

Phylogenetic analysis of jumping spider opsins revealed a birth and death of colour vision evolution in the arthropod lineage. Phylogenetic position of jumping spider opsins revealed that at least three opsins had aleady existed before the Chelicerata-Pancrustacea split. In addition, sequence comparison between jumping spider Rh3 and the shorter wavelength-sensitive opsins of insects predicted that an opsin of the ancestral arthropod had the lysine residue responsible for UV sensitivity. These results strongly suggest that the ancestral arthropod had at least trichromatic vision with a UV pigment and two visible pigments. Thereafter, in each pancrustacean and chelicerate lineage, the opsin repertoire was reconstructed by gene losses, gene duplications, and function-altering amino acid substitutions, leading to evolution of color vision.



The most remarkable and distinguishing characteristic of salticid spiders lies in their development of high visual acuity, particularly with respect to their large, tubular principal eyes (also known as anterior medial eyes, or AME) (Figure 1). Converging with vertebrates, these spiders use six different muscles to move each AME eye tube, through both translation and rotation (Land 1969a, 1969b), and they are also equipped with three different opsins, indicative of trichromatic color vision (Koyanagi et al. 2008). Visual acuity of these animals is far greater than that of any other terrestrial invertebrates (Blest 1985). Phylogenetic reconstruction of the evolution of these opsins suggests that UV receptors diverged from the visible light receptors of spiders long before the Chelicerata―Pancrustacea split, but that the subsequent evolution of two different visible light receptors (accounting for trichromatic vision in the Salticidae) took place much later (Koyanagi et al. 2008; see also Oakley 2003). Future study of the opsins of other chelicerates, and the Araneae in particular, will certainly help to clarify the relationship of salticids to other spider families.

Fossil record
Hill and Richman (2009) proposed that the first jumping spiders (Salticidae) appeared in the Late Cretaceous (at least 65 million years ago), and that species were multipling around the Oligocene–Miocene boundary (about 23 million years ago). While cladistic analyses, including both DNA and  morphology suggested this hypothesis, Penney (2010) was concerned that the hypothesis was not backed up by  palaeontological evidence. Although Grimaldi and colleagues (2002), Néraudeau and colleagues (2002) and Kaddumi (2005) wrote of fossil jumping spiders in Cretaceous amber (in New Jersey, France and Jordan reseptively), both Hill and Richman and Penney believe that these were misidentifications. Wunderlich (2004) notes that Eocene Baltic amber has shown only one primitive salticid subfamily, while later Miocene amber has yielded four subfamilies, and he suggestised that the multication of jumping spiders occured during the Cenozoic era rather than during the Mesozoic.

Taxonomy
In late 2011, the Museum and Institute of Zoology in Warsaw recorded 18 species of Portia among about 5,509 species and about 250 genera of Salticidae (jumping spiders), which is the largest family of spiders.

The genus name Portia was introduced by Ferdinand Karsch in 1878, and in the same year Tamerlan Thorell introduced genus name Sinis, which was a synonym for Portia. In 1859 Carl Ludwig Doleschall described Salticus fimbriatus, which now called Portia fimbriata.

The acknowledged species are:
 * Portia africana (Simon, 1886) — West, Central Africa
 * Portia albimana (Simon, 1900) — India to Vietnam
 * Portia assamensis Wanless, 1978 — India to Malaysia
 * Portia crassipalpis (Peckham & Peckham, 1907) — Singapore, Borneo
 * Portia deciliata Strand, 1907 — Madagascar
 * Portia fimbriata (Doleschall, 1859) — Nepal, Sri Lanka, Taiwan to Australia
 * Portia heteroidea Xie & Yin, 1991 — China
 * Portia hoggi Zabka, 1985 — Vietnam
 * Portia jianfeng Song & Zhu, 1998 — China
 * Portia labiata (Thorell, 1887) — Sri Lanka to Philippines
 * Portia orientalis Murphy & Murphy, 1983 — Hong Kong
 * Portia quei Zabka, 1985 — China, Vietnam
 * Portia schultzi Karsch, 1878 — Central, East, Southern Africa, Madagascar
 * Portia songi Tang & Yang, 1997 — China
 * Portia strandi Caporiacco, 1941 — Ethiopia
 * Portia taiwanica Zhang & Li, 2005 — Taiwan
 * Portia wui Peng & Li, 2002 — China
 * Portia zhaoi Peng, Li & Chen, 2003 — China

As of autumn 2011 the Museum and Institute of Zoology in Warsaw also noted an unnamed Portia species "Chak 30". Chakrabarti, 2011 based on photographs from India.