Newly discovered spitting spider shows very unusual social tendencies.

January 2006. California Academy of Sciences entomologist, Jeremy Miller, travelled to Eastern Madagascar to study the areas spiders. Jeremy Miller and his colleague, Hannah Wood, were the first arachnologists to survey the dry, deciduous forests of the region, so it was no surprise to discover a new species.

What was surprising, however, was the behavioural traits they discovered in a new species of spitting spider. These talented arachnids trap their prey from up to 60 millimetres away (10 times their body length) by gobbing out a mixture of venom and glue. Although impressive as this spitting is, however, it was not this behaviour that was so surprising. The big surprise was that the spiders live together in colonies.

 

Communal living seems mundane compared to projectile poison, but it is actually very rare among spiders. Most spiders are solitary once they reach adulthood, they seek each other out for one of only 2 reasons: to mate or to eat one another (or to appear in Harry Potter films). However, a very few species are more tolerant toward their kin. Of the roughly 40,000 known species of spiders about 20 live in cooperative family groups that can stay together for generations. By cohabiting, these social spiders share the work of web building and capturing prey.

The new spitting spider from Madagascar (Scytodes sp.) lives in groups of as many as 16, including juveniles and adults of both sexes. They build webs by weaving together debris, leaves, and branches with strands of silk. As well as providing a home, these webs, which are about the size of a large orange, also help to ensnare passing prey. Once a potential snack lands on the web, the spiders team up to help tackle the prey. Approaching from multiple angles, they use their back legs to comb silk over their prey and if necessary they spray the entangled intruder with toxic, sticky spit. The whole family participates in the capture, and they share the spoils of their labour quite freely, as even spiders that did not assist in the kill are allowed to eat.

These spitting spiders can subdue much bigger prey by working as a team than they could alone. On one occasion, Miller watched a single female try to snare a roach that was twice her size, but the bigger bug got away. However roaches of a similar size were successfully captured, however, when 2 or more spiders worked together. Teams of spiders were also seen to hunt other large prey such as moths and flies.

Courtesy of the California Academy of Sciences