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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 ...
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 ...
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]
The body of acorn worms is worm-shaped and divided into an anterior proboscis, an intermediate collar, and a posterior trunk. The proboscis is a muscular and ciliated organ used in locomotion and in the collection and transport of food particles. The mouth is located between the proboscis and the collar. The trunk is the longest part of the animal.
Peristalsis. A time-space diagram of a peristaltic wave after a water swallow. High-pressure values are red, zero pressure is blue-green. The ridge in the upper part of the picture is the high pressure of the upper esophageal sphincter which only opens for a short time to let water pass. Peristalsis (/ ˌpɛrɪˈstælsɪs / PERR-ih-STAL-siss ...
Torquaratoridae. The acorn worms or Enteropneusta are a hemichordate class of invertebrates consisting of one order of the same name. [2] The closest non-hemichordate relatives of the Enteropneusta are the echinoderms. [3] There are 111 known species of acorn worm in the world, [4] the main species for research being Saccoglossus kowalevskii.
The parasitic worms are the cause of soil-transmitted helminthiases. They are taxonomically classified along with arthropods, tardigrades and other moulting animals in the clade Ecdysozoa. Unlike the vaguely similar flatworms, nematodes have a tubular digestive system, with openings at both ends.
Infection of the digestive system by adult tapeworms causes abdominal symptoms that, whilst unpleasant, are seldom disabling or life-threatening. [45] [46] However, neurocysticercosis resulting from penetration of T. solium larvae into the central nervous system is the major cause of acquired epilepsy worldwide. [47]