Spiders are the last creatures you’d think were socially conscious. But new research by George Uetz at the University of Cincinatti and Linda Rayor at Cornell University shows that the little critters have woven a social heirarchy just as strict as any cotillion ball. Listen as we spin a story of size and privilege in an eight-legged society.
Cruising for web sites. I'm Bob Hirshon and this is Science Update.
About the most social thing most spiders do is have their mate for dinner. But Colonial Orb Weaving spiders are regular party animals. According to Entomologist Linda Rayor, they live in groups of up to a thousand or more.
"Each of them has their own individual orb web, and they defend their own orb web, but they're found in these large groups of hundreds of individuals."
Dr. Rayor and her colleagues found that these spiders have established a complex social structure. The larger spiders get choice web sites in the core- where the large females lay their eggs. As the baby spiders grow, they get pushed out of the core toward the fringe of the colony. There they can get more food and grow faster. Once they get large, though, they become the most favored meal of predatory wasps. So they migrate inward again to the relative safety of the core to lay their own eggs.
"Colonial orb weaving spiders are excellent model systems for studying how social animals group themselves within social groups."
She says understanding how these aggressive, small-brained creatures maintain a large, peaceful group can provide insights into the societies of other animals, from the simplest to the most complex.
For the American Association for the Advancement of Science, I’m Bob Hirshon.
Making Sense of the Research
Animal groups are everywhere! Wolves run around in packs; fish band together in schools; thousands of ants make up a colony. Perhaps you've seen a flock of sheep, a parliament of owls, a mob of kangaroos, a sloth of bears, or a swarm of insects - the list goes on and on. But does grouping together necessarily make animals social? All living things relate to other members of their species, but do they depend on each other to survive? In some species, such as the social insects, individuals are so dependent on the group that they cannot survive as individuals. This could be said also for humans, who are dependent on others until they reach maturity. Social organization of some kind is common to all animals. But in cases of true social organization, animals of the same species literally depend on one another to survive.
Can you distinguish a group of animals from a society of animals? What traits do they share? What traits do social animals exhibit that others do not?
Using resources provided in the Going Further section below, try to determine what makes the animals group together and what benefits the group procures that individuals could not (i.e.: safety in numbers, lookouts, grooming, companionship, etc.). Then decide which species you think are truly "social butterflies" and which are merely "part of the gang!"
Now try to answer the following questions:
- How many Colonial Orb weaving spiders have been know to live in one group?
- Where in the group structure do the larger spiders choose to build their webs?
- What benefits do the smaller spiders procure by living on the fringe of the colony?
- What types of behaviors do these spiders exhibit that makes them social animals?
- How many other animals can you name that would be considered social?
To learn more about Linda Rayor's work read Spider Solidarity Forever, found at Science News Online. And to learn more, in general, about Colonial Orb weaving spiders check out the Cornell University News article entitled The early spider catches the web site.
For great spider pictures and information visit Spiderz Rule.
See Social Behavior in Animals, from Encyclopedia Britannica, for general information on the social behaviors of animals.
To begin thinking about how specific animals interact with each other and whether or not they are truly social, investigate elephants on the African Wildlife Foundation site.