BIOL 1604 Lecture Notes - Lecture 11: Enzyme, Pinworm Infection, Wuchereria Bancrofti
Document Summary
Have a cuticle (nonliving external layer secreted by the epidermis) They molt: ecdysozoans: animal groups whose members shed the cuticle as they grow, ecdysis: shedding the outer curricular layer. Triploblastic bilateral pseudocoelomates (body cavity not entirely lined with mesoderm) Cuticle: mainly composed of collagen secreted by underlying epidermis (hypodermis) Cuticle protects and contains the high hydrostatic pressure exerted by fluid. Sensory system includes papillae and setae for touch. Unique sensory amphids or in the pseudocoelom phasmids. Ring of nerve tissue with ganglia around pharynx gives rise to nerves and dorsal and ventral nerve cords. Excretory system may include gland cells and canals, it opens via excretory pore. Free living (marine, freshwater, soil) and parasitic. Most dioecious and dimorphic: males are smaller than females: internal fertilization, parthogenesis occurs rarely. After fertilization, shelled zygotes or embryos are stored in the uterus until deposition. Four juvenile stages, each separated by a shedding of the cuticle.
