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Bodies are divided into segments called metameres (are externally linked by circular rings called annuli). Is the division of the bods into segments. Each segment contains similar components of all major organ systems.
tiny chitinous have setae. Setae is used in locomotion, swimming, and burrowing (except for leeches)
Annelid Body plan
2 part head composed of a prostomium and a peristomium followed by a segmented body and a terminal portion called pygidium (bears the anus). Head and pygidium are not segments. Contains circulatory, respiratory, nervous, and excretory structures. Periotenba of adjacent segmens meet to form septa.
lined with peritnomeum that covers all the organs. filled with fluid and serves as a hydrostatic skeleton that helps the worm move
Longitudinal dorsal and ventral blood vessels, ventral nerve cord
Follow the same path as the digestive system
have well differentiated head with specialized sense organs, paired appendages called parapodia on most segments, and no clitellum
Sometimes called sand worms, live in mucous-lined burrows in or near low tide, active at night, about 200 segments, parapodia is used for creeping and swimming. Feed on small animals, other worms, and a variety of larval forms
most abundant and diverse of the polychaetes, flattened bodies are covered in broad scales, carnivorous and eat a wide variety of animals, many are commensals living in burrows of polychaetes or in association with cnidarians, molluscs, or echinoderms.
have hollow brittle setea that contain a poisonous secretion. Feed on corals, gorgonians, and othe cnidarians
tubes secreted can be parchmentlike, or leathery, some firm calcaerous, and some burrow into sand or mud. tubes attach to rocks on other surfaces. Most sedentary tube and burrow dwellers are particle feeders, using cilia or mucus to obtain food, typically plankton or detritus. Some are deposit feeders who protrude their heads above the mud extend long tentacles over the surface to find food
More than 3000 species, live in various habitats, include earthworms and many species that live in fresh water.
Class of Annelid that are terrestrial or freshwater, some are parasitic, and a few live in the marine water. Most have setae which can be long or short, straight or curved, blunt or needlelike, or arranged singly or in bundles.
Called night crawlers, burrow in moist rich soil, live in tunnels. Most are scavengers, are hermaphroditic
Food enters the mouth and moves along the esophagus, then moves to the crop, gizzard which grinds the food into small pieces. Digestion occurs in the intestine. Absorption is increased by the typhlosole.
tissue that surrounds the intsetine and is the center for symthesis of glycogen and fat and also functions in excretion.
Leeches, have no setae, do not have a variable number of segments, they have 34. Possess anterior and posterior suckers. Lack distinct coelomic compartments. Occur predominantly in freshwater habitats. Most are abundant in tropical areas.
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