Caterpillars on the Move
The current Science Daily has some remarkable findings about the hornworm's locomotion. They discovered that the caterpillar uses its gut independently to move.
"The Tufts-led team reported that the gut of the crawling tobacco hawkmoth caterpillar (Manduca sexta) moves forward independently of and in advance of the surrounding body wall and legs, rather than moving along with them.
Anyone who has ever observed caterpillars knows that they crawl from back to front in waves. But advanced imaging reveals a surprising picture of what goes on inside.
The researchers used synchronized x-ray and visible light microscopy and videos to study the relative timing of movements of the crawling caterpillar's gut body wall and prolegs (unjointed leg-like structures on the mid-body that grip.)
They found that the gut -- essentially a tube suspended at the rear and head of the caterpillar and decoupled from the body wall -- moved nearly a full step in advance of the surrounding structures. In contrast, gut movement was "in step" with motion of the head and rear.You could say that this gives a whole new meaning to the term "bowel movement".
Furthermore, points within the gut moved at different rates, suggesting that the gut was effectively shortening and lengthening during each crawl cycle."
Moths Remember Early Caterpillar Lessons
Back in 2008, Science Daily reported a study on the same species. Scientists showed that a caterpillar can learn lessons that its moth will remember after completing metamorphosis.
"The Georgetown researchers found that tobacco hornworm caterpillars could be trained to avoid particular odors delivered in association with a mild shock. When adult moths emerged from the pupae of trained caterpillars, they also avoided the odors, showing that they retained their larval memory. The Georgetown University study is the first to demonstrate conclusively that associative memory can survive metamorphosis in Lepidoptera.
The brain and nervous system of caterpillars is dramatically reorganized during the pupal stage and it has not been clear whether memory could survive such drastic changes.
The findings of the Georgetown researchers suggest the retention of memory is dependent on the maturity of the developing caterpillar's brains. Caterpillars younger than three weeks of age learned to avoid an odor, but could not recall the information as adults, whereas older caterpillars, conditioned in the final larval stage before pupation, learned to avoid the odor and recalled the information as adults.
The results have both ecological and evolutionary implications, as retention of memory through metamorphosis could allow a female butterfly or other insect to lay her eggs on the type of host plant that she herself had fed on as a larva, a behavior that could shape habitat selection and eventually lead to development of a new species."
|Wasp Larva on Caterpillar|
|Sphinx Moth- tomato hornworm|