BI256 Study Guide - Final Guide: Endothermic Process, Merostomata, Omnivore
Document Summary
Possess a cuticle, which is a nonliving external layer secreted by the epidermis. Cuticle: stiff, hardened outer body wall that restricts growth and must be molted via ecdysis (synapomorphy between ancestors) Regulation of molting is achieved by hormone ecdysone (hormone associated with growth) Do not share common body plan with lophotrochozoan. Members of nematoda, nematomorpha, and kinorhyncha are pseduocoelomates (don"t have a true coelomic cavity) The pseudocoelom is used as a hydrostatic skeleton in nematodes, kinorhynchs, and priapulids while loricifera species vary from being pseudocoelomate and acoelomate. Most important pseudocoelomate animals, both in abundance and impact on man. Found in soil, oceans, freshwater habitats, plants, and all kinds of animals. About 25,000 species- due to new grouping half a million species may exist. Found in all habitats in all biomes such as good topsoil may contain billions of nematodes per acre. Found in all animal and plant species, making nematode infestation studies important in agriculture and biomedical sciences.
