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Annelids (Round, Segmented worms) ; Are animals, to be more precise, invertebrates (no backbone) They are round and segmented, have no legs, and may be parasitic, aquatic or beneficial. Examples ...


Annelids are considered members of the Lophotrochozoa, a "super-phylum" of protostomes that also includes molluscs, brachiopods, flatworms and nemerteans. The basic annelid form consists of multiple segments. Each segment has the same sets of organs and, in most polychates, has a pair of parapodia that many species use for locomotion.


List of parasitic organisms. Jump to navigation Jump to search This is an incomplete list of ... parasites that live on but not within their hosts, for example, attached to their skin) Arthropoda. ... Annelids. Hirudinea (some leeches) Monogeneans ...


This class includes the 500 species of leeches, flattened, predacious or parasitic annelids equipped with suckers used for creeping. Leeches range in length from about 1/2 in. to 8 in. (1 cm–20 cm); most are under 2 in. (5 cm) long. They are commonly black, brown, green, or red, and may have stripes or spots. ...


Leeches, which number about 300 species, inhabit freshwater or humid environments and are carnivorous or parasitic on other organisms—e.g., all marine leeches are parasitic on fish. Size range and diversity of structure. The length of annelids varies from a fraction of an inch to more than six metres (about 20 feet).


Annelids, or true-segmented worms, are members of the animal phylum Annelida, the most complex of all wormlike groups of organisms. Annelids are commonly found in terrestrial, as well as marine, brackish, estuarine, and freshwater ecosystems worldwide. Most annelids are free-living, although several species have parasitic, mutualistic, or commensal relationships with other animals, and many ...


However, there are also parasitic annelids that feed off of a host organism, with blood-sucking leeches being the most common example. Earthworms exist in huge numbers all around the world in virtually any soil that isn't frozen.


The Phylum Annelida is divided into 3 classes, one of which the Clitellata could really be called a Superclass, it contains three subclasses, the Oligochaeta, the Branchiobdella and the Hirundinea. The other two classes are the Polychaeta which contains the largest number of species and the Aelosomatida which contains very few.


Start studying Ch. 27 Worms. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Search. ... Parasitic species are typically more complex in structure than free-living species. ... What evidence is there that annelids are more closely related to clams and snails than to flatworms or roundworms?


A parasite is an organism that lives on or in a host organism and gets its food from or at the expense of its host. There are three main classes of parasites that can cause disease in humans: protozoa, helminths, and ectoparasites. Protozoa Protozoa are microscopic, one-celled organisms that can be ...