Annelid Anatomy

In several groups of sea snails and sea slugs parapodium refers to lateral fleshy protrusions. In annelids parapodia are paired un jointed lateral outgrowths that bear the chaetae.

Bio385 Annelida

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Annelid anatomy. Pogonophora siboglinidae were first discovered in 1914 and their lack. Most of the species in the annelids carry a bristles called the setae and parapodia a pair of appendages. Annelid worms are excellent examples of a hydrostatic skeleton in the form of a coelom in action.

Sensory nerves leave the brain and run forward into the prostomium extreme anterior end and first segment. Para beyond or beside podia feet refers to two different organs. Myzostomida live on.

In the 19th century they were assigned to. Segmented worms including the leeches and terrestrial earthworms is relatively simple in structure. These animals have well developed neuronal and digestive systems.

The term parapodium gr. The echiura have a checkered taxonomic history. The brain of most annelids phylum annelida.

The digestive system is quite uneven but it is specialized. In sum annelid anatomy can be described as a tube within a tube because of the presence of a coelom and the shape of the worm. Some species bear a specialized band of segments known as a clitellum.

Annelids whose bodies swell and shrink according to water levels. Annelids show the presence numerous chitinous projections termed chaetae and polychaetes possess parapodia. Annelid phylum name annelida also called segmented worm any member of a phylum of invertebrate animals that are characterized by the possession of a body cavity or coelom movable bristles or setae and a body divided into segments by transverse rings or annulations from which they take their name.

Segmentation is seen in internal anatomy as well which is called metamerism. The coelom is reduced in leeches and setae are lacking a few specialized forms including leeches. Simple metanephridia and short nephridioducts.

Start studying annelid anatomy. In front of the true segment is the prostomium and peristomium that carry the mouth and at the back of them lies the posterior lies the pygidium the place where the anus is located. The earthworm brain is a bilobed mass lying above the pharynx in the third body segment.

In earthworms the hydrostatic skeleton or coelom is surrounded by sheaths of longitudinal and circular muscles. Some other groups of animals have been classified in various ways but are now widely regarded as annelids.

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