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A skinny, nine-year-old
Japanese-American girl with short straight black hair
walked down a slope to the creek where she and her two older brothers
like to go fishing. As she got close to the pier, she saw a dead
catfish floating in the water. Why had the fish died? Curiosity
got the better of her. She picked up the catfish, pulled out a
pocket knife she had borrowed from her Dad, and slit the fish
open. Then she stood there staring in amazement at the fish's
insides.
The little girl, Judy Sakanari, grew up to be a scientist at
the University of California at San Francisco where she studies
parasites that are found in fish. A parasite is an animal that
lives on or inside another animal known as its host, and is dependent
on the host for its food to survive. As a nine-year-old, Judy
didn't know what a parasite was or what it looked like when she
opened up that catfish. But now she regularly examines fish for
parasites. One parasite she studies is a worm about an inch long
that is found in fish.
Many animals have parasites. Dogs and cats can have parasites
like ticks and fleas on their skin and roundworms and tapeworms
inside. Humans can also get infected with parasites. "Basically
I am interested in studying parasites and the relationships of
the parasites with their hosts," Judy said. "One of
the larger questions I am interested in answering is how parasites
cause disease in humans."
Unlike the relationship between a parasite and its host, some
relationships among animals are mutually beneficial. That means
each needs the other, but each also helps the other. Judy gives
one example of a "cleaning station" where shrimp position
themselves on rocks: "A fish will come by and just open its
mouth, and the shrimp will start picking the debris, bacteria,
and parasites off the fish's gills, and off its skin. That way
it benefits the fish because it's getting cleaned, and the shrimp
also benefits because it's getting a meal."
However, the relationship parasites have with fish or animals
is not mutually beneficial. The parasite benefits from living
off its host, but the host often is harmed by the parasite. For
example, parasites can cause large ulcers in the stomachs of marine
animals. They can also make pets and people very sick.
(excerpted from the biography written by Mary Knudson, and the
entire biography is available on the Parasite Sleuth CD-ROM.)
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