SCIENCE / MEDICINE : Insects Run but Crabs Gallop

Cockroaches, beetles, dogs and humans all employ the same gait when running, researchers at UC Berkeley revealed last week. Insects employ a running gait and not a walking gait, they have found, while crabs actually gallop.

Biologist Robert Full discovered these facts while testing the various species on treadmills enclosed in airtight plastic boxes that allow measurement of even the minuscule amount of oxygen consumed by the smaller species. The results may have application in robotic design.

The main thing Fuller has found, he said, is that the energy required in getting from one place to another is not greatly affected by how many legs an animal has or even by the way it moves. The energy required to walk or run depends much more heavily on the amount of force needed simply to hold the body up against gravity than on the mechanical power needed to swing the legs and propel the body forward.

Rather than smoothness of gait or even the number of legs an animal has, the key to economy of movement, Fuller has found, lies in the time it takes each leg to go through its whole cycle of movement and the force produced by the leg muscles.