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Earthworms have many internal parasites, including protozoa, platyhelminthes, mites, and nematodes; they can be found in the worms' blood, seminal vesicles, coelom, or intestine, or in their cocoons (e.g. the mite Histiostoma murchiei is a parasite of earthworm cocoons [53]).
Earthworms and their kin, in the subclass Oligochaeta, lack eyes but have photoreceptor cells in the skin, especially in the dorsal portion of the anterior end. They also lack parapodia and appendages on the prostomium, the body and the periproct (terminal segment on which the anus is located).
The frontmost section, called the prostomium (Greek προ- meaning "in front of" and στομα meaning "mouth") contains the brain and sense organs, while the rearmost, called the pygidium (Greek πυγιδιον, meaning "little tail") or periproct contains the anus, generally on the underside.
The remaining segments have no appendages, but they do have a small number of bristles, or chaetae. These tend to be longer in aquatic forms than in the burrowing earthworms, and can have a variety of shapes. Each segment has four bundles of chaetae, with two on the underside, and the others on the sides.
In Britain, it is primarily called the common earthworm or lob worm (though the name is also applied to a marine polychaete). In North America , the term nightcrawler (or vitalis ) is also used, and more specifically Canadian nightcrawler , referring to the fact that the large majority of these worms sold commercially (usually as fishing bait ...
They grow through and project through a secondary or accessory cell of a type called a tormogen, which generates the special flexible membrane that connects the base of the seta to the surrounding integument. Depending partly on their form and function, setae may be called hairs, macrotrichia, chaetae, or scales. The setal membrane is not ...
In ecosystems, earthworms such as Lumbricus rubellus increase the rate of transfer between trophic levels by making it easier for plants to uptake nutrients. In food chains, earthworms such as Lumbricus rubellus are primary consumers whose role is converting the energy synthesized by photosynthetic plants into food for animals at higher trophic ...
Since then the last four have all been subsumed into a single phylum, the Chordata, while his Insecta (which included the crustaceans and arachnids) and Vermes have been renamed or broken up. The process was begun in 1793 by Lamarck, who called the Vermes une espèce de chaos (a sort of chaos) [ a ] and split the group into three new phyla ...