Gasteracantha fornicata

Also called the crab spider, spiny-backed orbweaver, spiny orbweaver spider, crab-like orbweaver spider, crab-like spiny orbweaver spider, jewel spider, spiny-bellied orbweaver, jewel box spider or smiley face spider) is a species of spider.

Web decorations
This spider adds little tufts of silk to its web. These seem not to function to attract prey. Possibly one function is to warn larger animals not to accidentally destroy the web, or to act as camouflage.

A Argyrodes fissifrons spider on the web of a Gasteracantha fornicata.

A tinny black spider share the same web with this spicky spaider. The extreme long legs of this tiny spider sugest it is a Argyrodes spider. Spider from this Argyrodes Genus do not spin thsir own own web but live in web of bigger spider.

The abdomen is triangular in profile, with the spinnerets pointing downwards and the hind-end pointing backwards
Spiders of the genus Argyrodes live in the webs of larger spiders. They are "food stealers", helping themselves to insects trapped in the web of the host, or a freshly killed victim that is being consumed by the host. Most of these "commensals" have long and thin legs and silvery spots on the bodies. The males have grotesque-looking bumps on their head. Presumably because they are too small, the hosts appear to tolerate their presence. After mating, the male often seals the female's epigyne with a resinous plug preventing the female from further mating.

Most members of the family Theridiidae have a "comb" of serrated bristles on the last segment (tarsus) of the fourth leg. The comb helps to draw sticky threads of silk from the spinnerets to wrap any prey caught in the web. When the victim is securely enveloped in silk, the spider will then approach it and bite through the silky bundle, extinguishing any further signs of struggle. The snare is an irregular three-dimensional structure



Yellow spots under the abdomen


Females are 5 to 9 mm long and 10 to 13 mm wide. The six abdominal spine-like projections on the abdomen are characteristic. The carapace, legs and underside are black with yellow spots under the abdomen.

Variations occur in the colour of the upperside of the abdomen with black spots on white to yellow ground colour and red spines or yellow instead of white.

Spines are sometimes black. Like in many other spiders, males are much smaller (2 to 3 mm long) and longer than wide. They are similar to the females in colour but have a gray abdomen with white spots and the spines are reduced to four or five stubby projections


More about Malaysian spiders  10-7-2009  July 24, 2010 01:51:48 PM

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