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Oligochaeta (/ ˌ ɒ l ɪ ɡ ə ˈ k iː t ə,-ɡ oʊ-/) [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.
Leeches are segmented parasitic or predatory worms that comprise the subclass Hirudinea within the phylum Annelida.They are closely related to the oligochaetes, which include the earthworm, and like them have soft, muscular segmented bodies that can lengthen and contract.
The pharynx (pl.: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the esophagus and trachea (the tubes going down to the stomach and the lungs respectively). It is found in vertebrates and invertebrates, though its structure varies across species. The pharynx carries food to the esophagus and air to the larynx.
Food enters at the mouth. The pharynx acts as a suction pump; its muscular walls draw in food. In the pharynx, the pharyngeal glands secrete mucus. Food moves into the esophagus, where calcium (from the blood and ingested from previous meals) is pumped in to maintain proper blood calcium levels in the blood and food pH. From there the food ...
In general, however, they possess a pair of jaws and a pharynx that can be rapidly everted, allowing the worms to grab food and pull it into their mouths. In some species, the pharynx is modified into a lengthy proboscis. The digestive tract is a simple tube, usually with a stomach part way along.
The body cavity immediately behind the mouth opening, known as the oral cavity (or cavum oris in Latin), [2] is also the first part of the alimentary canal, which leads to the pharynx and the gullet. In tetrapod vertebrates , the mouth is bounded on the outside by the lips and cheeks — thus the oral cavity is also known as the buccal cavity ...
Oligochaeta is a genus of Asian flowering plants in the tribe Cardueae within the family Asteraceae. [2] [3] [4] Oligochaeta is native to central, southern, and southwestern Asia. They are annual plants that grow in mountain and steppe habitat. [5]
Arhynchobdellida, the proboscisless leeches, are a monophyletic order of leeches.They are defined by the lack of the protrusible proboscis that defines their sister taxon, the Rhynchobdellida.