and personality are strongly influenced by participation in groups, and
individuals living in stable environments seem more able to develop
their own distinctive styles than individuals who face frequent
sounds like human experience, but this finding came from research on
social spiders. While most of the world's 43,000 varieties of spiders
work alone as they spin webs and devour prey, Stegodyphus dumicola
is one of the 35 or so arachnid species that could make an arachnophobe
flee in horror. These social spiders collaboratively build massive webs
that allow them to capture prey bigger than they are, and they organize
their activities and divide their labors. And as Natalie Angier writes in a New York Times story,
research on these unusual creatures may provide fresh insights into
such human mysteries as where personality comes from and why some
individuals are innately shy while others are naturally aggressive. Jonathan N. Pruitt,
PhD, a biologist at the University of Pittsburgh, who studies social
spiders, told Angier, "It's very satisfying to me that the most maligned
of organisms may have something to tell us about who we are."
People and animals differ hugely in such traits as shyness, boldness, and adventurousness. Writing in the Proceedings of the Royal Society B, Dr. Pruitt and Kate Laskowski, of the Leibnitz Institute of Freshwater Ecology and Inland Fisheries
in Berlin, report that social spiders display individual
predispositions early. Further, spiders living in a stable, predictable
environment didn't become conformists. They became more individualistic
and had more pronounced personal quirks than spiders that were
experimentally shifted from one group to another. And personality tended
to dictate how labor was divided.
explains that among honeybees, caste depends on age-the youngest tend
the young, while older bees forage for food and defend the hive. Ants
wind up as soldiers or workers depending on their nutrition when they
are larvae. Social spiders find their niche in community operations
based on such individual characteristics as size and temperament.
Pruitt and colleagues found that, the innately aggressive spiders were
in charge of capturing prey and defending the colony while more docile
spiders tended the young. How do you discover spider personality? In one
method the Times story describes, researchers puffed air at
the spiders through a bulb-topped syringe. The bold ones bounced back
from the perceived threat in five or fewer seconds, while the more timid
ones took 10 seconds or longer. And the stable groups had the greatest
variety of bold and shy. Researchers even found that whole colonies can
have distinctive personalities, just as human neighborhoods can.
are discovering more and more animals that have traits we once
considered exclusively human. So we can marvel at spider individuality.
We can also be glad we don't share the Stegodyphus approach to family
life. The father spiders commit infanticide and the mothers are suicidal.
Females attach their egg cocoons to the web and guard them until babies
hatch. Male Stegodyphus spiders like to steal the eggs, forcing the
female to replace the cocoon and use the miscreant's sperm to fertilize
at least some of her eggs. Once the babies hatch, the mother feeds her
young by regurgitating most of her own meals directly into their mouths.
When the babies are about a month old, they attack the mother,
injecting her with their venom and digestive enzymes, and eat her. When
she is consumed, the siblings cannibalize as many of their brothers and
sisters as they can before the survivors embark on new lives. Read the Times story here.
left image by Dr VB Whitehead