Internal Anatomy of Insects

The insect body is a slightly to pronounced elongate, cylindrical structure. Its shape is determined by the integument and associated muscles. As is the case with the wide variation in external appearance among taxa, there is considerable variation in internal structure. The same basic systems are normally present in all insects, of course, but their expression varies with their behavior and ecology. Similarly, the systems found in the immature and adult stages may be quite similar in some insects or quite different in others, depending not only on the development of reproductive structures in adults but also on the feeding ecology on the insects. There are several important internal systems that together provide many of the unique characteristics that make an insect different from most other animals (Fig. 27).

Internal Anatomy of Insects, Figure 27

Caterpillar with integument partially removed to expose the internal anatomy (modified from Essig 1942).