Polychaete: Polychaete, any worm of the class Polychaeta (phylum Annelida). About living species are known. Polychaetes, which include rag worms. Reino: Animalia Filo: Annelida Clase: Polychaeta Orden: Phyllodocida, Eunicida, Sabellida, Orbiniida, Spionida, Terebellida, Chaetopterida, Capitellida. Noun 1. Polychaeta – marine annelid worms class Polychaeta Annelida, phylum Annelida con un total de 19 especies pertenecientes a la clase Polychaeta.
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Polychaeteany worm of the class Polychaeta phylum Annelida. About 8, living species are known. Polychaetes, which include rag worms, lugworms, bloodworms, sea mice, and others, are marine worms notable for well-defined segmentation of the body. Unique among annelids, most polychaete body segments bear a pair of parapodia flat, lobelike outgrowths with setae, or tiny bristles.
Polychaetes vary in size from a few millimetres to about 3 m 10 feet and are divided informally into two groups; the errantia, or free-moving forms, and sedentaria, or tube-dwelling forms.
The head has short sensory projections palps and tentacles. The body is often brightly coloured. The diet consists of minute aquatic plants and animals in some species, while others are purely carnivorous. The sexes are usually separate; sperm and eggs are discharged directly into the water, where fertilization occurs.
Larvae are ciliated and free-swimming.
As in some mollusk species, the early larvae are trochophores. Some polychaete species are hermaphroditic i.
Polychaetes play an important role in turning over bottom sediments in the sea. The palolo worm q. Other species are used by humans as bait for fishing.
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The Editors of Encyclopaedia Britannica. Learn More in these related Britannica articles: In some the brain can be divided into a forebrain, a midbrain, and a hindbrain; a single pair of circumesophageal or circumpharyngeal connectives leave the brain, surround the anterior gut, and connect with the ventral nerve…. Typically, as in polychaetes, it has an alimentary canal with mouth and anus and a ring of ciliated cells arranged anterior to the mouth.
It also possesses a sensory organ and rudiments of mesoderm. Cilia around the mouth bring in food—unicellular plants and other small particles.
PPT – PHYLUM ANNELIDA PowerPoint Presentation – ID
Testes and ovaries usually develop, though not invariably, in many body segments; and polyvhaeta sperm and eggs, often in enormous numbers, are stored in the coelom. In oligochaetes all of which are monoecious on the polyxhaeta. More About Polychaete 11 references found in Britannica articles Assorted References major reference In annelid annotated classification In annelid: Annotated classification larval stage In animal development: The larval stage mating behaviour In reproductive polychaera Segmented worms migration patterns In migration: Lower invertebrates physiology chemoreceptive mechanisms In chemoreception: Specialized chemosensory structures circulatory system In circulatory system: Annelida nervous system In nervous system: Annelids reproductive system In animal reproductive system: Annelids and mollusks In animal reproductive system: Annelids and mollusks View More.
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Dog, Canis lupus familiarisdomestic mammal of the family Canidae order Carnivora. It is a subspecies…. Horse, Equus caballusa polychasta herbivorous mammal of the family Equidae.
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