Multiple personalities

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Most people have no problem assigning personalities to beloved pets, but they stop short of extending the courtesy to invertebrates. New research suggests we should be more generous.

J. Chadwick Johnson, now at Arizona State University's West campus in Phoenix, and Andrew Sih of the University of California, Davis, studied Dolomedes triton, a species of fishing spider that hides underwater when threatened by predators. Hiding spiders may emerge for a gulp of air, but quickly return below if they're still afraid. Johnson and Sih induced sixty captive female fishing Spiders to hide by poking them with a pencil, then either let them be or tempted them to the surface with food or a courting male. Individual females were remarkably consistent through all three tests in the percentage of time that they remained in hiding relative to other females. In words, their ranking on a scale of "timid to bold" remained constant. What's more, juveniles' relative boldness tended to persist into adulthood.

More and more studies are revealing consistent character traits--personalities, if you will--in animals as disparate as fish, amphibians, birds, and bighorn sheep. What's next--self-assured slugs? (Animal Behaviour)

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