Page 34 - 2009 DT 7 issues

Per-so-na-li-ty! credible Hulk, but fail to attract the la- nessee in Knoxville, compared two
dies in courtship. The idea of “person- different groups of the same species
ost pet owners will hap- ality” might explain the role various of funnel spiders from Arizona and
pily describe their little traits play in terms of animal behaviors New Mexico for aggressiveness. The
Mtreasure’s charming person- and how they affect outcomes. Arizona spiders came from an area
alities, even if you don’t ask. While Ann Hedrick of the University of along a river. The New Mexican spi-
aspects of personality are understand- California, Davis studied the funnel ders’ environment was arid grassland.
ably attributed to mammals, and even spider (Agelenopsos aperta) to record Individuals from each population
birds, would we ever describe insects any individual behavioral differences were paired by body size and by ter-
or spiders in the same light? Not in hunting. This spider constructs a ritory size. Then they were clocked to
hardly. But some studies are showing sheet of silk hovering just above the see who was faster in rushing out of
that even the lowly spider may exhibit ground or around a plant support. The their funnel hole when prey appeared.
personality, or in science-speak, a set center of the sheet sports a funnel that The New Mexico strain, even when
of “behavioral syndromes.” According drops into a safe haven under a rock, a tested in the lab, could whip the fan-
tree root or a clump of grass. If the web
to Science News, Chad Johnson, a sci- nies of the Arizona strain. They were
entist at the Arizona State University is trespassed upon by a rival or prey, faster and predictably more aggressive
West in Glendale, has been researching as a population.
just that possibility. “That evidence provides a first
As desert southwest cities have step for demonstrating personality—
grown, so have their black widow predictable variation between two
spider populations. In Phoenix, black groups of individuals of the same
widows have become as numerous as species,” according to Science News.
cockroaches. Johnson, like a handful There were other links, as well.
of other scientists, puzzled as to why a The funnel web, while a great
ambush device in hunting hapless
cranky loner like the black widow had
prey, leaves the spider in the funnel
taken so readily to city life. Could it
partly exposed to predation by birds,
have something to do with personal-
mice and other animals that are, in
ity, he asked? The jury is still out, but
turn, hunting it. Since the web isn’t
perhaps some of the newcomers to the
sticky, it won’t trap an intruder and
desert embody traits that help them to
it won’t protect the spider, either. In
thrive in the big city. an experiment to test the spiders’ fear
Biologists usually describe ani- factor, Hedrick and Reichert used
mals in terms of the general traits of a squeezable bulb to puff air at the
an entire species. Johnson and other surface of the web, causing vibrations
researchers began trying to identify similar to those of an incoming bird.
diverse patterns of individual behavior Western black widow Both spider populations dove into
within a species. Invertebrates such the owner springs out of the funnel to their tunnels for cover. Even though a
as spiders, crickets, dumpling squid investigate. Some individual spiders spider’s position in the funnel is risky,
and water striders are being studied are more aggressive defenders of their the New Mexicans were faster to tiptoe
to determine whether individuals dis- webs than others in the same popula- back to their hunting spots in the web
play different “personalities” . . . um, tion. Similar differences were reflected than the Arizona spiders were after
“behavioral syndromes.” when comparing entire funnel spider the “intrusion” signals ended. While
In some species, an especially populations to each other. the researchers never used the word
macho spider might snag a lot of prey, Hedrick, along with Susan “personality” in their papers during the
becoming a spider version of the In- Riechert of the University of Ten- 1980s and 1990s, Hedrick describes

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