Zoo Exam 2 - chapter 17 annelida

Common characteristics of annelids

exhibit segmentation, live in marine/freshwater/and moist terrestrial habitats, setae - tiny ch8itinous bristles, surface is covered with an epidermis and a thin outer layer cuticle, coelom is filled with fluid and serves as a hydrostatic skeleton, have both longitudinal muscles and circular muscles,

Segmentation

bodies composed of serially repeated units, each unit contains components of most organ systems, allows for greater complexity in structure and function

Class polychaeta examples

sandworms, tubeworms, fanworms

Class Polychaeta characteristics

more specialization of sensory organs - eyes, tolerate a wide range of salinity, no clitellum, well-differentiated head, paired appendages called parapodia on most segments, some are predators or scavengers, most have gills for gaseous exchange, many have respiratory pigments, no permanent sex organs, monoecious, fertilization is external,

Class Oligochaeta example

night crawlers or earthworms

Class Oligochaeta characteristics

reproductive structure - clitellum, hermaphroditic (monoecious), occur in habitats from soil to freshwater, nearly all bear setae, scavengers, blood circulates in a closed system, no special gaseous exchange organs - gas exchange across body surface, lack eyes,

Class Hirudinida examples

leeches

Class Hirudinida characteristics

34 segments, lack setae and possess anterior and posterior suckers, most freshwater, some carnivores others parasites, hermaphroditic, form clitellum during breeding season, practice cross-fertilization,