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Unformatted text preview: herbivorous, parasitic, etc…. Important research animals (e.g. Caenorhabditis elegans) Important economically (both positively and negatively) Alternate ﬂexion of longitudinal muscles forms S-curves Good for moving through water, soil and tissues Muscles work in opposition to stiff, non-cellular collagen cuticle Gut and excretory system with separate exits Female genital pore mid-ventral, male ejaculatory duct exits at anus Some able to withstand extreme conditions (dry, cold, hot, etc.), recover when conditions improve Many species are parasites (some of man (table15.1, p. 300)) Ascaris (intestinal roundworm), consume intestinal contents Trichinella (muscle parasites) Enterobius (pinworm), another intestinal parasite (16% adult infection rate in U.S.) Ancyclostoma or Necator (hookworm), intestinal, consume blood in mass Filarial roundworms—infect lymphatic system (e.g. elephantiasis) Infect blood vessels (e.g. river blindness, heartworm (dogs)) Guinea worm—swallowed as juveniles in copepod, mature and migrate to under skin Traditionally wound out around a stick (origin of caduceus) Many others Phylum Gastrotricha Phylum Nematomorpha Phylum Acanthocephala proboscis within Bilateria by ﬁnding a nemalla spiralis) with a slow evolving 18s ith careful attention to unequal rate rovided evidence that the protostomes cladesPhylogeny andnAdapt...
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This note was uploaded on 11/29/2009 for the course BIOL 3454 taught by Professor Lab during the Spring '08 term at UT Arlington.
- Spring '08