Social Behavior in Spiders

According to New Scientist a new species of spiders has been discovered that lives in groups and cooperates when hunting:

According to Avilés, there are over 39,000 identified spider species. While she has seen just over 20 species cooperate, she has never encountered any species quite like Theridion nigroannulatum.
The spiders live in nests that house up to several thousand individuals which hunt by hanging threads from low lying leaves. They then hide upside down, beneath the leaves waiting for prey.
When an insect flies into the strands a group of spiders drop down and throw sticky webbing over it. To finish off the ambush they inject venom with their tiny jaws.

After the kill is made the spiders take turns carrying it back to the nest, which can be composed of anywhere from a few dozen to thousands of spiders (there seems to be a boom and bust cycle going on, which makes me wonder). The interesting thing is:

A further mystery is why the female spiders come in two different sizes. Among social insects, when females differ in size it is due to a division of labour. Bees are a classic example: large females lay eggs and small females search for food. With spiders this has not been observed before – T. nigroannulatum could be the first.

Here is a picture (also from New Scientist):

7 Responses

  1. Creepy and cool.

  2. And people think Eight Legged Freaks was just a movie!

  3. I wonder if there has been speculation on whether this is what spiders were like when they first evolved into Araneae from whatever order they came from. It would make sense, as many forms of insect are social, but seeing as the overwhelming majority of spiders fly solo, it could also be that this species is part of an evolutionary line that is to Araneae what Tarsiers are to Haplorrhini: the genus that separated early on in the order.

  4. spiders rule!

  5. let me tell u how i tricked my mom really good well my dad found a fackorange and black spider so i went into my liveing room and we have a rocking chair so i put it on the top and I said EWWWW THERES A SPIDER ON UR CHAIR and she was on her laptop so she got out of it and she said AIIIIIIIIIIIIIIIIIII THEN SHE KNOCKED IT OFF THEN i said I TRICKED U.BYE BYE

  6. I too am curious about the variance in size between females of the same species
    This is a really exciting find especially since it was noted on another URL that after the communal capture of the pray and bringing it back tot he nest, some of the spiders involved would not partake of that particular capture, but instead went back to their respective places of hiding to await another victim.

  7. I just witnessed a Big orange bumblebee being attacked and slowly killed by these little spiders they buried their jaws into the bees vulnerable spot between its head and its abdomen….They really are nasty little so and so’s. They rally do co operate with one another and they don’t give up until the victim is dead. I filmed them on my camcorder and you can clearly see them at work….. Yuk just so long as they don’t start fancying a taste of humans!!!!

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