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Portia fimbriata

By Andrea Jackson

Geographic Range

Portia fimbriata are found in the rainforests of Australia, Sri-Lanka, and Malaysia. (Jackson, 1992)

Habitat

P. fimbriata require the moist conditions found in tropical rainforests. (Jackson and Hallas, 1986)

Physical Description

The appearance of P. fimbriata is unlike that of other spiders. They are about 1 cm long, and have cryptic markings, tufts of hair and long spindly legs. Because of their unusual appearance, P. fimbriata are often mistaken for detritus by both prey and potential predators. (Jackson, 1992)

Reproduction

P. fimbriata are able to mate either on or off of the web. Male and female both participate in a courtship dance. This dance consists of a series of jerky walking, leg shaking and tapping behaviors. The male mounts the female, the female spins around on the male, and they copulate. Mating can also take place while both male and female are suspended in mid-air from a silk guyline. Interestingly, in other species of the genus Portia, when the female spins around on the male while suspended in air, she eats the male after copulation. P. fimbriata does not display this cannibalistic behavior.

Fertilization is delayed. About an hour after copulation, P. fimbriata males deposit a drop of sperm on the web. The female moves over the sperm deposit, and facilitates fertilization. (Jackson and Hallas, 1986; Jackson, 1992)

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • sexual
  • oviparous

Behavior

P. fimbriata are largely solitary.

P. fimbriata use their unusual appearance that is similar to detritus to evade other predators, and to help them approach prey. (Jackson, 1992)

Food Habits

P. fimbriata are primarily araneophagic, meaning they eat other spiders, including other salticids. P. fimbriata also eat insects and the eggs of other spiders.

P. fimbriata are predatory, and they use several methods of predation. One is aggressive vibratory mimicry, in which P. fimbriata climb on to the web of their victim and use their legs and palps to pluck signals on the web. They imitate the signals of their intended victim's prey. When the victim comes close to P. fimbriata, they make their attack.

P. fimbriata are specialists at catching cursorial jumping spiders. Most cursorial jumping spiders don't build typical webs, but they make small orb-like nests out of silk. P. fimbriata make vibratory signals on the silk of the nest. When the salticid pokes its head out to investigate, they attack. This is called nest probing.

Another type of predation used by P. fimbriata is cryptic stalking. In this method, the hunter moves very slowly. If the prey spider turns to face it, P. fimbriata pulls its palps back and out of the prey's view and freezes. In this position P. fimbriata resembles a piece of detritus. Eventually it approaches the prey from behind, and swoops in for the kill.

Other jumping spiders of the genus Portia exhibit aggressive mimicry, nest probing, or cryptic stalking. P. fimbriata is the only species that exhibits all three behaviors. P. fimbriata also displays species-specific predation tactics. The jumping spider Euryattus (species unknown), is sympatric with P. fimbriata in the rainforests of Queensland, Australia, but is not known to exist with any other P. fimbriata population. Euryattus females do not build a nest, but suspend a rolled-up leaf by silk guylines from a rock ledge or tree trunk. Male Euryattus go down guylines onto the leaves and court by flexing legs and making the leaf rock back and forth. The female comes out of the nest to either mate or drive the male away. P. fimbriata mimics the behavior of the male, and when the female comes out of the nest, P. fimbriata attacks. Populations of P. fimbriata that do not live with Euryattus in nature have been brought into captivity, and do not drop down from guylines to attack Euryattus in this way.

Unlike other salticids, P. fimbriata are web building spiders. P. fimbriata use their webs not only as nests, but as a mode of predation. They build their webs near, and fastened to, the webs of another species, creating a single compound structure. It then is easy for an individual P. fimbriata to invade the neighboring web. The web of P. fimbriata is not sticky, but sometimes does catch insects. In this situation, P. fimbriata usually do not eat the insect, but instead waits for spiders from the neighboring web to approach, and eats them instead. (Jackson and Wilcox, 1998; Jackson, 1985; Jackson, 1992; Li and Jackson, 1997)

  • Primary Diet
  • carnivore
    • eats non-insect arthropods
  • Animal Foods
  • eggs
  • insects
  • terrestrial non-insect arthropods

Economic Importance for Humans: Negative

There are no known adverse effects of Portia fimbriata on humans.

Conservation Status

This species has not been recognized as needing special conservation efforts.

Other Comments

P. fimbriata, like other salticids, has vision that is superior to that of most other spiders. P. fimbriata has six small lateral eyes that detect movement in a field of view that is as large as 360°. The two principal eyes are located on the front of the head and provide acute vision. (Jackson and Wilcox, 1998; Jackson, 1985)

Contributors

Andrea Jackson (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

saltatorial

specialized for leaping or bounding locomotion; jumps or hops.

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

venomous

an animal which has an organ capable of injecting a poisonous substance into a wound (for example, scorpions, jellyfish, and rattlesnakes).

References

Jackson, R. 1985. A web-building jumping spider. (Australian species *Portia fimbriata*). Scientific American, 253: 102-110.

Jackson, R. 1992. Eight-legged Tricksters: spiders that specialize in catching other spiders. BioScience, 42: 590-598.

Jackson, R., R. Wilcox. 1998. Spider-eating spiders. American Scientist, 86: 350-357.

Jackson, R., S. Hallas. 1986. Comparative biology of jumping spiders. New Zealand Journal of Zoology, 13: 423-489.

Li, D., R. Jackson. 1997. Influence of diet on survivorship and growth in *Portia fimbriata*, an araneophagic jumping spider (Arnae: Salticidae).. Canadian Journal of Zoology, 75: 1652-1658.

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