Sunday, December 2, 2001

Odyssey: Animal Angles

by Ruth Tenzer Feldman

This circus fits in the palm of your hand.
The performers are fleas. Yes, fleas!
Flea circuses were popular in Europe and the United States in the 1800s. There are still some left. One is Adam Gertsacov's Acme Miniature Circus, where fleas run a chariot race and balance a chair and pole. These tiny performers (about 0.1 to 1.0 centimeter long) can pull an object 130,000 times their weight and can leap horizontal or vertical distances 150 to 200 times their length at an acceleration 50 times faster than the Space Shuttle.
Circus fleas compress and release resilin, a super-elastic protein, in their leg and thorax muscles. In nature, this action catapults them upward, allowing bristles and hooks all over their bodies to snag a luckless animal host. In flea circuses, performers instinctively jump toward heat and carbon dioxide, and away from light.
It's easy to catch flea circus performers. There are hundreds of flea species, and they live everywhere, feeding on the blood of mammals and birds.
Fleas belong to the order Siphonaptera, meaning “wingless siphons.” Their mouths include barbs for piercing skin and hanging on tight. Ouch!
Gertsacov's circus performers are the human fleas Pulex irritans, meaning “irritating dust.” Some fleas are more than irritating. The rat flea Xenopsylla cheopis is an efficient carrier of bubonic plague, known during the Middle Ages as the Black Death. As plague-infected rats die, their fleas, which drink diseased rat blood, transmit the disease to humans. Plague is still around, but can now be cured.
Some flea species are not meant for the circus, as they don't jump. But jumpers or not, fleas were handy subjects for Anton van Leeuwenhoek in the 1600s. His microscope became known as the “flea glass.” What an entertaining fact!
PHOTO (COLOR): Nano-entertainment! A female cat flea (Clenocephalides felis) tows a miniature 19th-century cart along a human finger at a circus in Munich.
By Ruth Tenzer Feldman