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An earthworm is a soil -dwelling terrestrial invertebrate that belongs to the phylum Annelida. The term is the common name for the largest members of the class (or subclass, depending on the author) Oligochaeta. In classical systems, they were in the order of Opisthopora since the male pores opened posterior to the female pores, although the ...
The "pharynx" of the nematode worm is a muscular food pump in the head, triangular in cross-section, that grinds food and transports it directly to the intestines. A one-way valve connects the pharynx to the excretory canal. Pharynx of the flatworm Platydemus manokwari visible as the worm feeds on a snail.
Oligochaeta (/ ˌɒlɪɡəˈkiːtə, - ɡoʊ -/) [1] is a subclass of soft-bodied animals in the phylum Annelida, which is made up of many types of aquatic and terrestrial worms, including all of the various earthworms. Specifically, oligochaetes comprise the terrestrial megadrile earthworms (some of which are semiaquatic or fully aquatic), and ...
The nematodes (/ ˈnɛmətoʊdz / NEM-ə-tohdz or NEEM-; Greek: Νηματώδη; Latin: Nematoda), roundworms or eelworms constitute the phylum Nematoda. [3][4] They are a diverse animal phylum inhabiting a broad range of environments. Most species are free-living, feeding on microorganisms, but many species are parasitic. [3]
The earthworm is a limbless annelid worm with a hydrostatic skeleton that moves by peristalsis. Its hydrostatic skeleton consists of a fluid-filled body cavity surrounded by an extensible body wall. The worm moves by radially constricting the anterior portion of its body, increasing length via hydrostatic pressure.
A set of "valve cells" connects the pharynx to the intestine, but how this valve operates is not understood. After digestion, the contents of the intestine are released via the rectum, as is the case with all other nematodes. [20] No direct connection exists between the pharynx and the excretory canal, which functions in the release of liquid ...
Unidentified planarian. Planarians (triclads) are free-living flatworms of the class Turbellaria, [2][3] order Tricladida, [4] which includes hundreds of species, found in freshwater, marine, and terrestrial habitats. [5] Planarians are characterized by a three-branched intestine, including a single anterior and two posterior branches. [5]
Their pharynx, when everted, clearly consists of two portions, with a pair of strong jaws on the distal portion and usually with conical teeth on one or more areas of both portions. Most genera have no gills (if present, they are usually branched and arise on mid-anterior segments of body).