Portia (genus)

Taxobox


image_caption = female "P. fimbriata"
image_width = 250px
name = "Portia"
regnum = Animalia
phylum = Arthropoda
classis = Arachnida
ordo = Araneae
familia = Salticidae
subfamilia = Spartaeinae
tribus = Spartaeini
genus = "Portia"
genus_authority = Karsch, 1878
diversity_link = List of Salticidae species#Portia
diversity = 17 species
type_species = "Salticus fimbriatus"
type_species_authority = Doleschall, 1859
range_

range_map_width = 250px
subdivision_ranks = Species
subdivision = see text

Portia is a genus of jumping spider which feeds on other spiders (araneophagic).

Distribution

Hunting techniques

"Portia"s often hunt in ways that seem intelligent. Their favorite prey appears to be web-building spiders between 10% and 200% of the "Portia"’s size, in other words some prey species are very dangerous opponents. "Portia"s look rather like leaf detritus caught in a web, and this is often enough to fool web-building spiders, which have poor eyesight.cite journal
author=Harland, D.P., and Jackson, R.R. | date=2000
title=“Eight-legged cats” and how they see - a review of recent research on jumping spiders (Araneae: Salticidae)
journal=Cimbebasia | volume=16 | pages=231-240
url=http://www.cogs.susx.ac.uk/ccnr/Papers/Downloads/Harland_Cimb2000.pdf PDF | accessdate=2008-10-11 ] When stalking web-building spiders, "Portia"s try making different patterns of vibrations in the web that aggressively mimic the struggle of a trapped insect or the courtship signals of a male spider, repeating any pattern that induces the intended prey to move towards the "Portia". "Portia fimbriata" has been observed to perform vibratory behavior for three days until the victim decided to investigate.fact|date=October 2008 They time invasions of webs to coincide with light breezes that blur the vibrations their approach causes in the target's web; and they back off if the intended victim responds belligerently. "Portia"s that retreat may approach along an overhanging twig or rock, abseil down a silk thread and kill the prey. Other jumping spiders take detours, but "Portia" is unusual in its readiness to use long detours that break visual contact.

Laboratory studies show that "Portia" learns very quickly how to overcome web-buildng spiders that neither it nor its evolutionary ancestors would have met in the wild. "Portia"’s accurate visual recognition of potential prey is an important part of its hunting tactics. For example in one part of the Philippines local "Portia" spiders attack from the rear against the very dangerous spitting spiders, which themselves hunt jumping spiders. This appears to be an instinctive behavior, as laboratory-reared "Portia"s of this species do this the first time they encounter a spitting spider. On the other hand they will use a head-on approach against spitting spiders that are egg-carrying eggs. However experiments that pitted "Portia"s against convincing artificial spiders with arbitrary but consistent behavior patterns showed that "Portia"’s instinctive tactics are only starting points for a trial-and-error approach from which these spiders learn very quickly.cite book
author=Wilcox, S. and Jackson, R. | chapter=Jumping Spider Tricksters | pages=27-34
title=The Cognitive Animal: Empirical and Theoretical Perspectives on Animal Cognition
editor=Bekoff, M., Allen, C., and Burghardt, G.M. |publisher=MIT Press | date=2002 | isbn=0262523221] However they seem to be relatively slow "thinkers", which is not surprising as they solve tactical problems by using brains vastly smaller than mammalian predators'. Against other jumping spiders, which also have excellent vision, "Portia"s may mimic fragments of leaf litter detritus.fact|date=October 2008 When close to biting range, "Portia"s use different combat tactics against different prey spiders. On the other hand they simply stalk and rush unarmed prey such as flies, [cite journal
author=Harland, D.P., and Jackson, R.R.
title=A knife in the back: use of prey-specific attack tactics by araneophagic jumping spiders (Araneae: Salticidae)
journal=Journal of Zoology | volume=269 | issue=3 | pages=285-290 | date=April 2006
doi=10.1111/j.1469-7998.2006.00112.x ] and also capture prey by means of sticky webs.

Although taxonomically in the "jumping spider" family, it does not jump, because then it would lose its detritus camouflage.fact|date=October 2008 Unlike other jumping spiders, "Portia" sometimes builds a web which it fastens to the web of a future victim.fact|date=October 2008 Should the web catch insects, "Portia" will wait for the other spider instead of feeding on the insect.fact|date=October 2008

The visual acuity of jumping spiders', especially "Portia", exceeds by a factor of ten that of dragonflies, which have by far the best vision among insects; in fact the human eye is only about fives times sharper than a jumping spider's. They achieve this by a telephoto-like series of lenses, a four-layer retina and the ability to swivel their eyes and integrate images from different stages in the scan. As a result their vision is ten times more acute than that of dragonflies and one fifth as sharp as that of humans. The downside is that the scanning and integrating processes are relatively slow. They can see as clearly as a pigeon, but only a minute piece at a time.fact|date=October 2008 They are, for example, unable to discern the shape of a praying mantis, because it is too big for its field of vision.fact|date=October 2008

Reproduction

"Portia" exhibits a different mating behavior and strategy compared to other jumping spiders. In most jumping spiders, males mount females to mate. In "Portia" the female drops a dragline after the male mounts her, mating in mid-air. Before this happens the male shows off his legs and extends them stiffly and shakes them to attract the female. the female then drums on the web. Mating with Portia spiders can occur off or on the web.The spider also practices cannibalism before and after copulation. The female usually twists and lunges at the mounted male ("P. fimbriata" however, is an exception; it does not usually exhibit such behavior.). If the male is killed before completing copulation, the male sperm is removed and the male is then eaten. If the male finishes mating before being killed, the sperm is kept for fertilization and the male is eaten. A majority of males are usually killed during sexual encounters.

pecies

* "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 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

Footnotes

References

* (2000): 'Eight-legged cats' and how they see - a review of recent research on jumping spiders (Araneae: Salticidae). "Cimbebasia" 16: 231-240 [http://www.cogs.susx.ac.uk/ccnr/Papers/Downloads/Harland_Cimb2000.pdf PDF] - vision and behavior in "Portia" spiders.
* (2006): A knife in the back: use of prey-specific attack tactics by araneophagic jumping spiders (Araneae: Salticidae). "Journal of Zoology" 269(3): 285-290. DOI|10.1111/j.1469-7998.2006.00112.x
* (2007): [http://research.amnh.org/entomology/spiders/catalog/index.html The world spider catalog] , version 8.0. "American Museum of Natural History".

External links

* [http://salticidae.org/salticid/diagnost/portia/portia.htm Description in the "Diagnostic Drawing Library"]
* [http://habitatnews.nus.edu.sg/guidebooks/spiders/text/Portia_labiata.htm Guide to Common Singapore Spiders: "P. labiata"]
* [http://salticidae.org/salticid/diagnost/portia/labia-ph.htm Photographs of "P. labiata"]
* [http://salticidae.org/salticid/diagnost/portia/fimbr-ph.htm Photographs of "P. fimbriata"]
* [http://salticidae.org/salticid/diagnost/portia/schul-ph.htm Photographs of "P. schultzi"]
* [http://salticidae.org/salticid/diagnost/portia/afric-ph.htm Photographs of "P. africana"]
* [http://salticidae.org/salticid/diagnost/portia/quei-jph.htm Photographs of "P. quei"]
* [http://www.deh.gov.au/cgi-bin/species-bank/sbank-image.pl?id=sbank_209i.jfif&text=Portia%20fimbriata%20full%20frontalZZFringed%20Jumping%20Spider%20in%20full%20frontal%20viewZZCreator:%20Mike%20Gray%20%C2%A9%20M.%20Gray/Australian%20Museum Frontal view of "P. fimbriata"]
* [http://www.deh.gov.au/cgi-bin/species-bank/sbank-treatment.pl?id=75622 Information about "P. fimbriata"] (with distribution in Australia)
* [http://www.colostate.edu/Depts/Entomology/courses/en507/papers_2001/odenbeck.htm Prey capture and mating behavior in jumping spiders belonging to the genus Portia]