BI256 Lecture Notes - Lecture 14: Syncytium, Subcutaneous Tissue, Collagen
Document Summary
Nematodes chapter 17 bi 256 animals. Many protostomes possess a cuticle, which is a nonliving layer secreted by the epidermis. Cuticle: stiff, hardened outer body wall that restricts growth and must be molted via ecdysis. Ecdysozoans, like roundworms and arthropods molt cuticle as they grow. Regulation of molting achieved by the hormone ecdysone. Scientists assume that ecdysozoans have similar biochemical steps in molting. Ecdysozoans do not share same body plan. Members of nematoda, nematomorpha, and kinorhyncha are pseudocoelomates. Pseudocoelom is used as hydrostatic skeleton in nematodes, kinorhynchs, and priapulids while loricifera species vary from being pseudocoelomate and acoelomate. Panarthropoda contains arthropods, onychophorans, and tardigrades which have coelomate bodies but their body cavity is reduced in size. Nematodes are the most important pseudocoelomate animals, both in abundance and impact on man. Found worldwide in soil, oceans, freshwater habitats, plants, and all kinds of animals. Most people only know species as parasites in both man and their domesticated animals.
