Portia schultzi
Encyclopedia
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 those of males are 4 to 6 millimetres long. The carapaces
of both sexes are orange-brown with dark brown mottling, and covered with dark brown and whitish hairs lying over the surface. Males have white tufts on their thoraxes
and a broad white band above the bases of the legs,
and these features are less conspicuous in females. Both sexes have tufts of orange to dark orange above the eyes, which are fringed with pale orange hairs. Males' abdomens are yellow-orange to orange-brown with blackish mottling, and on the upper sides are black and light orange hairs, and nine white tufts. Those of females' are pale yellow and have black markings with scattered white and orange-brown hairs on the upper side. P. schultzi has relativity long legs than other Portia, and a "lolloping" gait.
While most jumping spiders focus accurately up to about 75 centimetres away, P. schultzi responds to a maximum of about 10 centimetres in good light, and ignores everything in very subdued light. Perhaps P. schultzi gains little from being alerted to more distant objectives, because this spider moves so slowly that it is unlikely to catch more distant prey. For prey, P. schultzi prefers web-based spiders, then jumping spiders, and finally insects. The females of P. schultzi and other Portias build "capture webs" to catch prey, and often join their own webs on to web-based spiders to catch the other spiders or their prey.
If a P. schultzi female is mature, a male P. schultzi will try to copulate with her, or cohabit with a sub-adult female and copulate while she is moult
ing. Portias usually mate on a web or on a dragline made by the female, and P. schultzi typically copulates for about 100 seconds, while Portias can take several minutes or even several hours. Females try to kill and eat their mates during or after copulation, and sub-adult females mimic adult females to attract males as prey. Contests between Portia females are violent, and embraces in P. schultzi typically take 20 to 60 seconds. Sometimes one female knocks the other on her back and the other may be killed and eaten if she does not right herself quickly and run way. When hunting, P. schultzi 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
. These are joined by a small, flexible pedicel
, which allows the abdomen to move while spinning silk. The top of the cephalothorax is covered by a carapace. In the genus
Portia
, the carapace slopes gently upward almost to the back, then steeply down.
In spiders and other chelicerates, there is only one pair of appendages before the mouth, the chelicerae
, and in spiders these house fangs that inject poison into the prey. Behind the mouth is a pair of pedipalp
s ("palps" for short), and those of male spiders are quite large and are used for displaying and mating.
The bodies of female Portia schultzis are 5 to 7 millimetres long (smaller than other Portias), while those of males are 4 to 6 millimetres long. The carapaces of both sexes are orange-brown with dark brown mottling, and covered with dark brown and whitish hairs lying over the surface. Males have white tufts on their thorax
es and broad white band above the bases of the legs, and these features are less conspicuous in females. Both sexes have tufts of orange to dark orange above the eyes, which are fringed with pale orange hairs. Females' chelicerae are pale yellow with black markings at the ends, while males' orange-brown with darker markings, and those of both sexes have pale orange and white hairs. The abdomens of females are pale yellow with black markings and the upper sides have scattered white and orange-brown hairs. Males' abdomens yellow-orange to orange-brown with blackish mottling, and on the upper sides are black and light orange hairs, and nine white tufts. Those of females' are pale yellow and have black markings with scattered white and orange-brown hairs on the upper side, but no tufts. The legs of both sexes are unusually long and slender, and those of male's are orange-brown with darker markings while those of females are light yellow with blackish markings. In both sexes the final two segment of each leg has no other decorations, but the other segments in both sexes have brownish hairs and many robust spines, and those of males also scattered white tufts. The palps of both sexes have pale yellow hairs and white fringes. 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.
Like many species of spider, a P. schultzi 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.
'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. Jumping spider's main eyes can see from red to ultraviolet
.
In most jumping spiders the main eyes focus accurately on an object up to about 75 centimetres away. However, P. schultzi does not react at all to objectives when the light is under 100 lux
(100 is typical of a restaurant with only artificial lighting). Between 100 and 500 lux it detects and approaches the objective from distances up to 6 centimetres (500 lux is about the light in a room with sunlight through large windows), from 500 lux to 1500 lux (a very bright cloudy day) its response distance increases gradually to a maximum of about 10 centimetres, and stronger light causes no increase in the response distance. For comparison, Trite
auricoma swivels towards a movement up to 75 centimetres away and approaches targets from about 20 centimetres. Perhaps P. schultzi gains little from being alerted to objectives at distances because this spider moves so slowly that it is very unlikely to reach a more distant target in time to catch it.
Like all jumping spiders, P. schultzi can take in only a small visual field at one time, as the most acute part of a main eye can see all of a circle up to 12 millimeters wide at 20 centimeters away, or up to 18 millimeters wide at 30 centimeters away. 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.
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. schultzi female's capture web may be suspended from rigid foundations such as boughs and rocks, or from pliant bases such as stems of shrubs. Males of Portia do not build capture webs.
Portias hunt in all types of webs, while other cursorial spiders generally have difficulty moving on webs, and web-building spiders find it difficult to move in webs unlike those they build. 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 movements and the flaps on its legs make it resemble leaf detritus caught in the web and blown in a breeze. P. schultzi 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. schultzi, P. labiata
or any regional variant of P. fimbriata
, and next to a web spider's web, the web spider sometimes enters the Portia′s web, and the Portia pursues and catches the web spider.
The webs of spiders on which Portias prey sometimes contain dead insects and other arthropods which are uneaten or partly eaten. P. schultzi and some other Portias such as P. fimbriata (in Queensland) and P. labiata 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.
Occasionally a Portia is killed or injured while pursuing prey up to twice Portia′s size. In tests, P. schultzi is killed in 1.7% of pursuits and injured but not killed in 5.3%, P. labiata is killed in 2.1% and injured but not killed in 3.9%, 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. labiata
and three regional variants of P. fimbriata
.
For resting, 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. P. schultzi returns to its resting platform at night. While eating prey at dusk and with no platform nearby, one P. schultzi built a silk platform while holding the prey, and then continued eating.
P. schultzi does not respond to prey if the light is under 100 lux
(like a restaurant with only subdued artificial lighting), but responds to prey at distances from 6 to 10 centimetres as the light level increases. A test suggested that P. schultzi′s hunting is stimulated only by vision, as prey close but hidden caused no response. A preliminary check showed that lures got the same responses from P. schultzi as live prey, and then more detailed testing with the lures showed that: if the target moved erratically, P. schultzi did not pursue it; if the target was totally stationary, the spider approached very slow (between 5 and 100 millimetres per minute), with very long pauses in the final stages, and the sequence was not completed in 43% of cases; if the lure jiggled on the same spot, P. schultzi approached much faster and the sequence was almost always completed; if a lure was pulled directly away from P. schultzi, the spider followed, and faster if the lure was pulled, up to a limit (P. schultzi generally moves very slowly).
A female P. schultzi 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. schultzi′s size. A female P. schultzi is effective against insects up to twice P. schultzi′s size when the insect is stuck in a non-salticid's web, and against insects not in webs and up to P. schultzi′s size, while P. schultzi seldom pursues or catches a larger insect in the open. A female P. schultzi very seldom pursues or catches a larger insect in her own web, and is slightly less effective against smaller insects in P. schultzi′s web than in other situations. Males are less efficient in all cases.
A test in 1997 showed that P. schultzi′s preferences for different types of prey are in the order: web spiders; jumping spiders; and insects. These preferences apply to both live prey and motionless lures, and to P. schultzi specimens without prey for 7 days ("well-fed") and without prey for 14 days ("starved"). P. schultzi 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.
In a test, P. schultzi spiderlings took Drosophila
("fruit flies") almost as often as spiders. P. schultzi retreats from the sudden flights of houseflies
found in the open, but sometimes takes flies entangled in a web. Out of its web, P. schultzi rarely capture thomisids (non-web sit-and-wait predators, usually under 13 millimetres long ) in the open, as thomisids often wave their front legs when threatened.
If a spider walks under a P. schultzi female's capture web and the vertical distance is less than 8 centimetres, the P. schultzi often drops on to the prey too fast for a human eye to follow. If the P. schultzi misses, it quickly returns up its safety line to its vantage point and looks for another chance - and seldom misses the second time. Most drops cover two to four centimetres, as longer drops are often obstructed by the web.
When hunting a web spider in the prey's web, a P. schultzi walks very slowly towards the prey and then, when two to three centimetres away, pauses for some minutes. During this time the P. schultzi quivers very quickly with its whole body at regular intervals. In almost all cases the prey stays motionless. P. schultzi never plucks the web as Portia fimbriata
does.
Unlike the Queensland variant of P. frimbriata, P. schultzi has no special tactics when hunting other jumping spiders.
When hunting, mature females of P. fimbriata, P. africana, P. fimbriata, P. labiata, and P. schultzi emit olfactory signals that reduce the risk that any other females, males or juveniles of the same species may contend for the same prey. The effect inhibits aggressive mimicry against a prey spider even if the prey spider is visible, and also if the prey is inhabiting any part of a web. If a female of one of these Portias smells a male of the same species, the female stimulates the males to court. These Portia species do not show this behaviour when they receive olfactory signals from members of other Portia species.
, 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. schultzi, emit volatile pheromone
s into the air, and these generally attract males from a distance.
Among P. schultzi 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. 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. In P. schultzi 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. schultzi typically take 20 to 60 seconds. These occasionally include grappling that sometimes breaks a leg, but more usually the final move is a lunge. 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.
A female P. schultzi that sees a male may approach slowly or wait. The male then walks 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 run 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. schultzi typically copulates for about 100 seconds, while other genera can take several minutes or even several hours.
Females of P. schultzi, like those of P. labiata
, 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. shultzi and also P. labiata mimic adult females to attract males as prey.
P. schultzi 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. P. schultzi has been seen laying eggs in a rolled-up leaf in a web of Ischnothele karschi.
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. Like all arthropod
s, spiders moult and, after hatching, the life stage before each moult is called an "instar
". The distinctive tufts of P. schultzi juveniles appear in the third instar.
P. schultzi exuviae (discarded "skins") have been found both in their own webs and in those of I. karschi, which has suggested that P. schultzi moults in the open. In one case, while its new skin was still pale and soft, its spinnerets were still stuck in the discarded skin, and the spider slowly twirled for about 90 seconds until it was free. The spider's body then darkened quickly to the normal colouration, and some time later the spider hung in its usual upside-down posture in the web.
(in South Africa
) in the south to Malindi
(in Kenya
) in the north, and westwards to the Great Rift Valley
, and also in West Africa
and Madagascar
.
P. schultzi, along with a large variety of spiders and insects, is often found in the dense, large webs of the diplurid
Ischnothele karschi (about 15 millimetres long), which are especially abundant in partly cleared secondary bush where rain forests have been cut down, and usually about one metre above the ground. A survey of one area suggested that there is about one P. schultzi per three I. karschi webs. P. schultzi is also found in its own web and those of other spiders, on tree trunks and the walls of buildings, and in leaf litter.
as of June 2011. This species has been named Portia schultzii (Karsch, 1878), Brettus martini (Simon, 1900), Linus lesserti (Lawrence, 1937), Linus alboguttatus (Lawrence, 1938), Portia schultzii (Wanless, 1978), Portia alboguttata (Wanless, 1978), Portia schultzi (Simon, 1901; Jackson & Hallas, 1986; Próchniewicz, 1989), and the last name has been used since then.
Wanless divided the genus Portia into two species group
s: the schultzi group, in which males' palps have a fixed tibia
l apophysis
; and the kenti group, in which the apophysis of each palp in the males has a joint separated by a membrane. The schultzi group includes P. schultzi, P. africana, P. fimbriata
, and P. labiata
.
Portia 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...
which ranges from South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
in the south to Kenya
Kenya
Kenya , officially known as the Republic of Kenya, is a country in East Africa that lies on the equator, with the Indian Ocean to its south-east...
in the north, and also is found in West Africa
West Africa
West Africa or Western Africa is the westernmost region of the African continent. Geopolitically, the UN definition of Western Africa includes the following 16 countries and an area of approximately 5 million square km:-Flags of West Africa:...
and Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
. In this species, which is slightly smaller than some other species 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, the bodies of females are 5 to 7 millimetres long, while those of males are 4 to 6 millimetres long. The carapaces
Carapace
A carapace is a dorsal section of the exoskeleton or shell in a number of animal groups, including arthropods such as crustaceans and arachnids, as well as vertebrates such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron.-Crustaceans:In crustaceans, the...
of both sexes are orange-brown with dark brown mottling, and covered with dark brown and whitish hairs lying over the surface. Males have white tufts on their thoraxes
Thorax
The thorax is a division of an animal's body that lies between the head and the abdomen.-In tetrapods:...
and a broad white band above the bases of the legs,
and these features are less conspicuous in females. Both sexes have tufts of orange to dark orange above the eyes, which are fringed with pale orange hairs. Males' abdomens are yellow-orange to orange-brown with blackish mottling, and on the upper sides are black and light orange hairs, and nine white tufts. Those of females' are pale yellow and have black markings with scattered white and orange-brown hairs on the upper side. P. schultzi has relativity long legs than other Portia, and a "lolloping" gait.
While most jumping spiders focus accurately up to about 75 centimetres away, P. schultzi responds to a maximum of about 10 centimetres in good light, and ignores everything in very subdued light. Perhaps P. schultzi gains little from being alerted to more distant objectives, because this spider moves so slowly that it is unlikely to catch more distant prey. For prey, P. schultzi prefers web-based spiders, then jumping spiders, and finally insects. The females of P. schultzi and other Portias build "capture webs" to catch prey, and often join their own webs on to web-based spiders to catch the other spiders or their prey.
If a P. schultzi female is mature, a male P. schultzi will try to copulate with her, or cohabit with a sub-adult female and copulate while she is 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. Portias usually mate on a web or on a dragline made by the female, and P. schultzi typically copulates for about 100 seconds, while Portias can take several minutes or even several hours. Females try to kill and eat their mates during or after copulation, and sub-adult females mimic adult females to attract males as prey. Contests between Portia females are violent, and embraces in P. schultzi typically take 20 to 60 seconds. Sometimes one female knocks the other on her back and the other may be killed and eaten if she does not right herself quickly and run way. When hunting, P. schultzi 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...
. These are joined by a small, flexible pedicel
Pedicel (spider)
The pedicel of a spider is a small, flexible cylinder that joins the cephalothorax and abdomen. This helps the spider to spin silk without moving the cephalothorax....
, which allows the abdomen to move while spinning silk. The top of the cephalothorax is covered by a carapace. In the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Portia
Portia (genus)
Portia is a genus of jumping spider which feeds on other spiders . They are remarkable for their hunting behaviour which suggests they are capable of learning and problem solving, traits normally attributed to much larger animals....
, the carapace slopes gently upward almost to the back, then steeply down.
In spiders and other chelicerates, there is only one pair of appendages before the mouth, the chelicerae
Chelicerae
The chelicerae are mouthparts of the Chelicerata, an arthropod subphylum that includes arachnids, Merostomata , and Pycnogonida . Chelicerae are pointed appendages which are used to grasp food, and are found in place of the chewing mandibles most other arthropods have...
, and in spiders these house fangs that inject poison into the prey. Behind the mouth is a pair of pedipalp
Pedipalp
Pedipalps , are the second pair of appendages of the prosoma in the subphylum Chelicerata. They are traditionally thought to be homologous with mandibles in Crustacea and insects, although more recent studies Pedipalps (commonly shortened to palps or palpi), are the second pair of appendages of the...
s ("palps" for short), and those of male spiders are quite large and are used for displaying and mating.
The bodies of female Portia schultzis are 5 to 7 millimetres long (smaller than other Portias), while those of males are 4 to 6 millimetres long. The carapaces of both sexes are orange-brown with dark brown mottling, and covered with dark brown and whitish hairs lying over the surface. Males have white tufts on their thorax
Thorax
The thorax is a division of an animal's body that lies between the head and the abdomen.-In tetrapods:...
es and broad white band above the bases of the legs, and these features are less conspicuous in females. Both sexes have tufts of orange to dark orange above the eyes, which are fringed with pale orange hairs. Females' chelicerae are pale yellow with black markings at the ends, while males' orange-brown with darker markings, and those of both sexes have pale orange and white hairs. The abdomens of females are pale yellow with black markings and the upper sides have scattered white and orange-brown hairs. Males' abdomens yellow-orange to orange-brown with blackish mottling, and on the upper sides are black and light orange hairs, and nine white tufts. Those of females' are pale yellow and have black markings with scattered white and orange-brown hairs on the upper side, but no tufts. The legs of both sexes are unusually long and slender, and those of male's are orange-brown with darker markings while those of females are light yellow with blackish markings. In both sexes the final two segment of each leg has no other decorations, but the other segments in both sexes have brownish hairs and many robust spines, and those of males also scattered white tufts. The palps of both sexes have pale yellow hairs and white fringes. 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, including P. schultzi, 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 P. schultzi 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
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 schultzi 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. 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...
.
In most jumping spiders the main eyes focus accurately on an object up to about 75 centimetres away. However, P. schultzi does not react at all to objectives when the light is under 100 lux
Lux
The lux is the SI unit of illuminance and luminous emittance, measuring luminous flux per unit area. It is used in photometry as a measure of the intensity, as perceived by the human eye, of light that hits or passes through a surface...
(100 is typical of a restaurant with only artificial lighting). Between 100 and 500 lux it detects and approaches the objective from distances up to 6 centimetres (500 lux is about the light in a room with sunlight through large windows), from 500 lux to 1500 lux (a very bright cloudy day) its response distance increases gradually to a maximum of about 10 centimetres, and stronger light causes no increase in the response distance. For comparison, Trite
Trite
Trite is a genus of jumping spiders.Trite may also refer to:* Trite , a historical currency used in Ancient Lydia* "Trite", a song by Sage Francis from Sick of Waiting Tables...
auricoma swivels towards a movement up to 75 centimetres away and approaches targets from about 20 centimetres. Perhaps P. schultzi gains little from being alerted to objectives at distances because this spider moves so slowly that it is very unlikely to reach a more distant target in time to catch it.
Like all jumping spiders, P. schultzi can take in only a small visual field at one time, as the most acute part of a main eye can see all of a circle up to 12 millimeters wide at 20 centimeters away, or up to 18 millimeters wide at 30 centimeters away. 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
Members of the genus PortiaPortia (genus)
Portia is a genus of jumping spider which feeds on other spiders . They are remarkable for their hunting behaviour which suggests they are capable of learning and problem solving, traits normally attributed to much larger animals....
have 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. schultzi female's capture web may be suspended from rigid foundations such as boughs and rocks, or from pliant bases such as stems of shrubs. Males of Portia do not build capture webs.
Portias hunt in all types of webs, while other cursorial spiders generally have difficulty moving on webs, and web-building spiders find it difficult to move in webs unlike those they build. 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 movements and the flaps on its legs make it resemble leaf detritus caught in the web and blown in a breeze. P. schultzi 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. schultzi, P. labiata
Portia labiata
Portia labiata is a jumping spider found in Sri Lanka, India, Burma , Malaysia, Singapore, Java, Sumatra and the Philippines. In this medium-sized jumping spider, the front part is orange-brown and the back part is brownish...
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.
The webs of spiders on which Portias prey sometimes contain dead insects and other arthropods which are uneaten or partly eaten. P. schultzi and some other Portias such as P. fimbriata (in Queensland) and P. labiata 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.
Occasionally a Portia is killed or injured while pursuing prey up to twice Portia′s size. In tests, P. schultzi is killed in 1.7% of pursuits and injured but not killed in 5.3%, P. labiata is killed in 2.1% and injured but not killed in 3.9%, 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 schultzi
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. schultzi, 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. labiata
Portia labiata
Portia labiata is a jumping spider found in Sri Lanka, India, Burma , Malaysia, Singapore, Java, Sumatra and the Philippines. In this medium-sized jumping spider, the front part is orange-brown and the back part is brownish...
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. schultzi | P. africana | P. labiata | P. fimbriata (Q) | P. fimbriata (NT) | P. fimbriata (SL) |
|---|---|---|---|---|---|---|---|
| Salticid | Tendency to pursue prey | 58% | 77% | 63% | 87% | 50% | 94% |
| Efficiency in capturing prey | 36% | 29% | 40% | 93% | 10% | 45% | |
| Web-building spider |
Tendency to pursue prey | 84% | 74% | 83% | 91% | 94% | 64% |
| Efficiency in capturing prey | 72% | 65% | 79% | 92% | 81% | 83% | |
| Insect | Tendency to pursue prey | 52% | 48% | 35% | 27% | 30% | 43% |
| Efficiency in capturing prey | 69% | 67% | 71% | 41% | 83% | 78% |
For resting, 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. P. schultzi returns to its resting platform at night. While eating prey at dusk and with no platform nearby, one P. schultzi built a silk platform while holding the prey, and then continued eating.
P. schultzi does not respond to prey if the light is under 100 lux
Lux
The lux is the SI unit of illuminance and luminous emittance, measuring luminous flux per unit area. It is used in photometry as a measure of the intensity, as perceived by the human eye, of light that hits or passes through a surface...
(like a restaurant with only subdued artificial lighting), but responds to prey at distances from 6 to 10 centimetres as the light level increases. A test suggested that P. schultzi′s hunting is stimulated only by vision, as prey close but hidden caused no response. A preliminary check showed that lures got the same responses from P. schultzi as live prey, and then more detailed testing with the lures showed that: if the target moved erratically, P. schultzi did not pursue it; if the target was totally stationary, the spider approached very slow (between 5 and 100 millimetres per minute), with very long pauses in the final stages, and the sequence was not completed in 43% of cases; if the lure jiggled on the same spot, P. schultzi approached much faster and the sequence was almost always completed; if a lure was pulled directly away from P. schultzi, the spider followed, and faster if the lure was pulled, up to a limit (P. schultzi generally moves very slowly).
A female P. schultzi 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. schultzi′s size. A female P. schultzi is effective against insects up to twice P. schultzi′s size when the insect is stuck in a non-salticid's web, and against insects not in webs and up to P. schultzi′s size, while P. schultzi seldom pursues or catches a larger insect in the open. A female P. schultzi very seldom pursues or catches a larger insect in her own web, and is slightly less effective against smaller insects in P. schultzi′s web than in other situations. Males are less efficient in all cases.
A test in 1997 showed that P. schultzi′s preferences for different types of prey are in the order: web spiders; jumping spiders; and insects. These preferences apply to both live prey and motionless lures, and to P. schultzi specimens without prey for 7 days ("well-fed") and without prey for 14 days ("starved"). P. schultzi 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.
In a test, P. schultzi spiderlings took Drosophila
Drosophila
Drosophila is a genus of small flies, belonging to the family Drosophilidae, whose members are often called "fruit flies" or more appropriately pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species to linger around overripe or rotting fruit...
("fruit flies") almost as often as spiders. P. schultzi retreats from the sudden flights of houseflies
Housefly
The housefly , Musca domestica, is a fly of the suborder Cyclorrhapha...
found in the open, but sometimes takes flies entangled in a web. Out of its web, P. schultzi rarely capture thomisids (non-web sit-and-wait predators, usually under 13 millimetres long ) in the open, as thomisids often wave their front legs when threatened.
If a spider walks under a P. schultzi female's capture web and the vertical distance is less than 8 centimetres, the P. schultzi often drops on to the prey too fast for a human eye to follow. If the P. schultzi misses, it quickly returns up its safety line to its vantage point and looks for another chance - and seldom misses the second time. Most drops cover two to four centimetres, as longer drops are often obstructed by the web.
When hunting a web spider in the prey's web, a P. schultzi walks very slowly towards the prey and then, when two to three centimetres away, pauses for some minutes. During this time the P. schultzi quivers very quickly with its whole body at regular intervals. In almost all cases the prey stays motionless. P. schultzi never plucks the web as Portia 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...
does.
Unlike the Queensland variant of P. frimbriata, P. schultzi has no special tactics when hunting other jumping spiders.
When hunting, mature females of P. fimbriata, P. africana, P. fimbriata, P. labiata, and P. schultzi emit olfactory signals that reduce the risk that any other females, males or juveniles of the same species may contend for the same prey. The effect inhibits aggressive mimicry against a prey spider even if the prey spider is visible, and also if the prey is inhabiting any part of a web. If a female of one of these Portias smells a male of the same species, the female stimulates the males to court. These Portia species do not show this behaviour when they receive olfactory signals from members of other Portia species.
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. schultzi, 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.
Among P. schultzi 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. 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. In P. schultzi 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. schultzi typically take 20 to 60 seconds. These occasionally include grappling that sometimes breaks a leg, but more usually the final move is a lunge. 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.
A female P. schultzi that sees a male may approach slowly or wait. The male then walks 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 run 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. schultzi typically copulates for about 100 seconds, while other genera can take several minutes or even several hours.
Females of P. schultzi, like those of P. labiata
Portia labiata
Portia labiata is a jumping spider found in Sri Lanka, India, Burma , Malaysia, Singapore, Java, Sumatra and the Philippines. In this medium-sized jumping spider, the front part is orange-brown and the back part is brownish...
, 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. shultzi and also P. labiata mimic adult females to attract males as prey.
P. schultzi 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. P. schultzi has been seen laying eggs in a rolled-up leaf in a web of Ischnothele karschi.
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. Like all arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
s, spiders moult and, after hatching, the life stage before each moult is called an "instar
Instar
An instar is a developmental stage of arthropods, such as insects, between each molt , until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or assume a new form. Differences between instars can often be seen in altered body proportions, colors, patterns, or...
". The distinctive tufts of P. schultzi juveniles appear in the third instar.
P. schultzi exuviae (discarded "skins") have been found both in their own webs and in those of I. karschi, which has suggested that P. schultzi moults in the open. In one case, while its new skin was still pale and soft, its spinnerets were still stuck in the discarded skin, and the spider slowly twirled for about 90 seconds until it was free. The spider's body then darkened quickly to the normal colouration, and some time later the spider hung in its usual upside-down posture in the web.
Ecology
P. schultzi′s range runs from DurbanDurban
Durban is the largest city in the South African province of KwaZulu-Natal and the third largest city in South Africa. It forms part of the eThekwini metropolitan municipality. Durban is famous for being the busiest port in South Africa. It is also seen as one of the major centres of tourism...
(in South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
) in the south to Malindi
Malindi
Malindi is a town on Malindi Bay at the mouth of the Galana River, lying on the Indian Ocean coast of Kenya. It is 120 kilometres northeast of Mombasa. The population of Malindi is 117,735 . It is the capital of the Malindi District.Tourism is the major industry in Malindi. The city is...
(in Kenya
Kenya
Kenya , officially known as the Republic of Kenya, is a country in East Africa that lies on the equator, with the Indian Ocean to its south-east...
) in the north, and westwards to the Great Rift Valley
Great Rift Valley
The Great Rift Valley is a name given in the late 19th century by British explorer John Walter Gregory to the continuous geographic trench, approximately in length, that runs from northern Syria in Southwest Asia to central Mozambique in South East Africa...
, and also in West Africa
West Africa
West Africa or Western Africa is the westernmost region of the African continent. Geopolitically, the UN definition of Western Africa includes the following 16 countries and an area of approximately 5 million square km:-Flags of West Africa:...
and Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
.
P. schultzi, along with a large variety of spiders and insects, is often found in the dense, large webs of the diplurid
Dipluridae
Funnel-web tarantulas , are a group of spiders in the infraorder Mygalomorphae, that have two pairs of booklungs, and chelicerae that move up and down in a stabbing motion...
Ischnothele karschi (about 15 millimetres long), which are especially abundant in partly cleared secondary bush where rain forests have been cut down, and usually about one metre above the ground. A survey of one area suggested that there is about one P. schultzi per three I. karschi webs. P. schultzi is also found in its own web and those of other spiders, on tree trunks and the walls of buildings, and in leaf litter.
Taxonomy
P. schultzi 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 June 2011. This species has been named Portia schultzii (Karsch, 1878), Brettus martini (Simon, 1900), Linus lesserti (Lawrence, 1937), Linus alboguttatus (Lawrence, 1938), Portia schultzii (Wanless, 1978), Portia alboguttata (Wanless, 1978), Portia schultzi (Simon, 1901; Jackson & Hallas, 1986; Próchniewicz, 1989), and the last name has been used since then.
Wanless divided the genus Portia into two species group
Species group
A species group is an informal taxonomic rank into which an assemblage of closely related species within a genus are grouped because of their morphological similarities and their identity as a biological unit with a single monophyletic origin.-Use:...
s: the schultzi group, in which males' palps have a fixed tibia
Tibia
The tibia , shinbone, or shankbone is the larger and stronger of the two bones in the leg below the knee in vertebrates , and connects the knee with the ankle bones....
l apophysis
Tubercle
A tubercle is generally a wart-like projection, but it has slightly different meaning depending on which family of plants or animals it is used to refer to....
; and the kenti group, in which the apophysis of each palp in the males has a joint separated by a membrane. The schultzi group includes P. schultzi, P. africana, P. fimbriata
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 P. labiata
Portia labiata
Portia labiata is a jumping spider found in Sri Lanka, India, Burma , Malaysia, Singapore, Java, Sumatra and the Philippines. In this medium-sized jumping spider, the front part is orange-brown and the back part is brownish...
.
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
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
(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...
.
External links
- Salticidae: Diagnostic Drawings Library - Portia schultzi by Jerzy Proszynski.