BIOMI 3310 Lecture Notes - Lecture 16: Body Cavity, Garry Bushell, Amphipoda
19 Apr 2018
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Includes: arthropods (insects, chelicerates, crustaceans, and myriapods, nematodes, all members of this group shed their exoskeleton (ecdysis) Nematomorphs: commonly called horsehair worms (originally believed to result from a horse hair falling into water troughs and turning into these worms, adults coil and tangle with each other, forming a knotted ball (compared to the gordian knot). Some adults have eyespots composed of innervated sacs beneath the transparent cuticle and backed by a pigment ring. Lack a mesodermal lining: didn"t evolve directly from any other pseudocoelomates, each phylum of pseudocoelomates evolved from acoelomates at different times. The pseudocoel isn"t a stage in the development of a coelom; the 2 developed independently. Nematomorphs that mate as adults in water change host behavior as larvae, causing their terrestrial hosts to seek water. Exit of the larvae often kills the host. Larvae may pass through one or more hosts (paratenesis) Females that get rid of the parasite may still lay eggs, but are otherwise sterilized.
