Behavioral responses to mechano-sensory information in a soft-bodied terrestrial animal.
van Griethuijsen, Linnea.
Abstract: Caterpillars are the larval stage of Lepidoptera, which consists of
butterflies and moths. Caterpillars were often seen as hydrostats, but recently researchers
have realized that caterpillars do not function as such. Reasons are their body plan, lack
of a fixed volume and the use of their substrate to transmit forces. These new insights
have changed how we think about movement in cat... read moreerpillars and are discussed in the first
chapter of this dissertation, which aims to give an overview of the current state of
knowledge on caterpillar locomotion. Chapter two discusses climbing. The movements of the
caterpillar when climbing and during horizontal locomotion are indistinguishable. The
similarities can be explained by 1) the caterpillar's strong grip to the substrate, which
it uses regardless of orientation, 2) the fact that it is a relatively small animal and
smaller animals tend to be less influenced by gravity due to their high locomotion costs
and 3) the caterpillar's slow movement. Chapter three also looks at locomotion, but focuses
on the use of sensory information to alter the normal stepping pattern. When stepping on a
small obstacle, information used to adjust the movement of the leg originates from body
segments anterior to that leg. In addition, information collected by the sensory hairs on
the proleg is used to fine-tune the movement mid swing. Chapter four focuses on the
response of the caterpillar to noxious stimuli. In this defense behavior the caterpillar
rapidly moves its mandibles toward the stimulation site. The accuracy with which the
caterpillar does this, is lower when responding to stimuli applied to dorsal and anterior
locations on the abdomen. An explanation can be found in the caterpillar's limited ability
to move its body into a tight curve and the lack of circular muscles. Chapter five
summarizes the findings and discusses them in the light of the recent discovery of the
movement of the gut during locomotion. The paper discussing this discovery can be found in
the appendix as well as a short description of the change in morphology when developing
from a hatchling into a fifth instar caterpillar.
Thesis (Ph.D.)--Tufts University, 2012.
Submitted to the Dept. of Biology.
Advisor: Barry Trimmer.
Committee: Harry Bernheim, David Cochrane, L. Michael Romero, Jason Rife, and Stacey Combes.
Keyword: Biology.read less