Living With Exoskeletons


Head Capsule of a Gypsy Moth Caterpillar Showing the Tentorium (arrows)

Insects have an external skeleton consisting of a layer of cells and secreted cuticle. Unlike vertebrates that have muscles attached to internal structures (bones) insects have most skeletal muscles attached to the exoskeleton. In some cases, it would be adaptive for insects to have internal points of attachment for skeletal muscles? What is an insect to do?

Invaginate! In the head of an insect, the outer layer of cells can form pits by growing inward. From the inside, the “pit” is a finger-like projection that contains cuticle and can be hardened into an attachment for the muscles in the head. In the caterpillar head (left), are three pits, one originating from back-center of the head and two originating from the front of the head, one to each side. The three invaginations meet in the center of the head and form a structure called the tentorium. Muscles of the mouthparts and antennae can make attachments to the tentorium. Through invagination, an insect with an external skeleton can create an internal skeletal structure that functions like a bone.

About jjneal

Jonathan Neal is an Associate Professor of Entomology at Purdue University and author of the textbook, Living With Insects (2010). This blog is a forum to communicate about the intersection of insects with people and policy. This is a personal blog. The opinions and materials posted here are those of the author and are in no way connected with those of my employer.
This entry was posted in by jjneal, Caterpillar Blogging, Environment. Bookmark the permalink.

One Response to Living With Exoskeletons

  1. Pingback: Living With Exoskeletons | Living With Insects Blog

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