Food serves not only to provide energy for activity but also to build up stores for long dormant periods, and, of course, it is the basis for growth. As arthropods, with a confining, almost nonexpandable, nonliving exterior cuticle, insects and their kin achieve size increases and maturity only by periodic spurts of growth following molting. This process takes place from a few to many times during the animal's life, although it ceases after adulthood in insects. Molting (or ecdysis) is preceded by a cessation of activity and catalysis of the lower cuticle layers when muscles and sense or gans assume new attachments. Only the old outer cuticular layer is shed, including the linings of the larger tracheae, foregut, and hindgut.

0 0

Post a comment