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jet-propelled roach by Sue Masterman    June 15 — Why is it almost impossible to squish a cockroach before it shoots out of sight behind the refrigerator while it is often quite easy to zap it with the nozzle of a vacuum cleaner?
     The answer, Dr Hananel Davidowitz of the NEC Research Institute in Princeton, N.J., says, is that the jet-propelled bug thinks with its behind.
     At least, the American cockroach does.
     Davidowitz should know. He has just published the results of his research into the thought processes of “Periplaneta amrericana” in the most recent edition of Nature magazine.
     The cockroach, he says, is able to sense minute changes in the air flowing round its body using tiny hairs on two posterior appendages called “cerci”—and that includes your foot coming down. Signals from those hairs feed into a group of 14 vital nerve cells which process the information. The result—now you see it, now you don’t.

Confused by Vacuum   The vacuum cleaner, however, has even smart roaches fooled.
     “If a vacuum cleaner approaches from behind a cockroach, the wind goes from its head to the nozzle. It thinks the attack is from the front and it turns round and runs straight into the nozzle,” the scientist says.
     Although it all seems very sophisticated for the lowly cockroach, the scientists were not surprised by their findings. ”They have been evolving for more than 300 million years. So they have got it right. They have been around a lot longer than we have,” said Davidowitz.
     Did you know cockroaches can feel pain? Scientists were told at a recent symposium held by the Universities Federation on Animal Welfare.
     Dr. Stephen Wick launched an impassioned appeal for “Roach Rights.”
     “If a chimp pulls its hand away after an electric shock, we say she presumably must have felt the analogous subjective experience to what we call pain,” he said. “But cockroaches, slugs and snails—which are not protected by legislation—also react the same way.”
     Reuters contributed to this report.

Cockroach Survival Tactics  Even though they’re ancient creatures that date back 350 million years, cockroaches are fairly high-tech survivors.
     “The cockroach’s strategy is to produce very few young and to live a very long time,” explains Philip Koehlar, a professor of urban entomology at the University of Florida.
     “Very few” and “very long” are relative terms. The housefly, for example, produces hundreds of eggs in a single lifetime and then dies within days. The Madagascar cockroach can reach the ripe old age of seven and produces less than 20 eggs during that long life span.
     What’s their secret to a long life? In addition to wearing motion-detecting sensors on the backs of their legs, cockroaches also wear sound detectors behind their legs and at the rear of their abdomen. The hair-like sensors, known as sensillae, detect air movement and variation in air pressure associated with sound.
     “They can even sense vibrations through the ground with these sensors,” says Koehlar, “so they can respond to vibrations of the surface they’re on.”
     For some species, those “ears” not only come in useful for detecting trouble, scientists think they may also use them for listening to their fellow roaches. Not all cockroaches “speak” (so to speak) but the Madagascar cockroach has a unique method of making a very loud sound.
     By contracting its body, this particular roach increases its blood pressure, which then exerts pressure on its windpipe. When it releases the opening to its windpipe (which happens to be located at the armpits) the escaping pressure makes a loud hissing sound.
     “It’s a pretty fierce sound that scares off predators,” says Koehlar.
     Flick on a flashlight in a dark room and you might see cockroaches scurrying for shelter. That’s because the insects also have two very big eyes that wrap around the front and sides of their heads. But studies have shown the roaches see mostly infrared and blue-green colors, so a yellow or red filter on a light might foil the roaches from sensing trouble.
     Cockroaches have also developed interesting ways of ensuring that their young make it to adulthood. Most species give birth to live young — highly unusual for insects — but a sure way to prevent other critters from feeding on their eggs.
     And if food is scarce, adolescent cockroaches can live on a very reliable resource — their parents’ feces.
— Amanda Onion

Copyright © 2001 [Alan Luke]. All rights reserved.
Revised: 10/15/11. Home