
                         Roanoke Times
                 Copyright (c) 1995, Landmark Communications, Inc.

DATE: WEDNESDAY, April 10, 1991                   TAG: 9104100276
SECTION: EXTRA                    PAGE: E-8   EDITION: METRO 
SOURCE: The Washington Post
DATELINE: WASHINGTON                                LENGTH: Short

CATERPILLARS AREN'T REALLY LAZY; THEY MOVE AS FAST AS THEY CAN

Are caterpillars naturally slow, or just lazy? This question, rarely in the forefront of biological inquiry, finally has been laid to rest in the current issue of Science magazine.

After months of painstaking experiments examining gypsy moth caterpillars that were obliged to run on a "custom made, motor powered, tiny little treadmill," a Rutgers University zoologist reports that the animals do not move fast because they are built to move slow. That is, writes Timothy Casey of the university's Cook College, "caterpillar organization precludes the possibility of high-speed locomotion."

So inefficient is the caterpillar's locomotor apparatus, Casey found, that it uses 4.5 times as much energy to move a given weight a given distance as do animals with skeletons.

The problem is biomechanical. Most animals that can move fast possess solid skeletons - either an internal skeleton like that of vertebrates or an exoskeleton like that of adult insects - that move when the muscles attached to them contract.

Caterpillars, by contrast, have fluid-filled "hydraulic" skeletons and move by rhythmic contractions of muscles that compress the animal's soft segments sequentially from back to front. The caterpillar plants its hind end and squeezes its body forward. Then it anchors itself with one or more sets of legs and waits for the next set of contractions.

by CNB