15-513: Polystilifera is an suborder of worms belonging to the order Hoplonemertea . Families: This nemertean -related article is a stub . You can help Misplaced Pages by expanding it . Worm Worms are many different distantly related bilateral animals that typically have a long cylindrical tube-like body, no limbs , and usually no eyes . Worms vary in size from microscopic to over 1 metre (3.3 ft) in length for marine polychaete worms (bristle worms); 6.7 metres (22 ft) for
30-459: A monophyletic group under current views of animal phylogeny. The similarities once offered in justification of the taxon, such as radial symmetry, are now taken to be the result of either incorrect evaluations by early researchers or convergent evolution , rather than an indication of a common ancestor. Because of this, the term is used mostly in a historical context. In the early 19th century, Georges Cuvier united Ctenophora and Cnidaria in
45-587: A backbone) such as blindworms and caecilians . Worms include several groups. The three main phyla are: Familiar worms include the earthworms , members of phylum Annelida . Other invertebrate groups may be called worms, especially colloquially. In particular, many unrelated insect larvae are called "worms", such as the railroad worm , woodworm , glowworm , bloodworm , butterworm , inchworm , mealworm , silkworm , and woolly bear worm . Worms may also be called helminths , particularly in medical terminology when referring to parasitic worms , especially
60-586: A group encompassing Cnidaria and Ctenophora. Although radial symmetry is usually given as a defining characteristic in animals that have been classified in this group, there are clear exceptions and qualifications. Echinoderms , for example, exhibit unmistakable bilateral symmetry as larvae , and are now in the Bilateria . Ctenophores exhibit biradial or rotational symmetry, defined by tentacular and pharyngeal axes, on which two anal canals are located in two diametrically opposed quadrants. Some species within
75-409: A pejorative epithet to describe a cowardly, weak or pitiable person. Worms can also be farmed for the production of nutrient-rich vermicompost . Radiata Radiata or Radiates is a historical taxonomic rank that was used to classify animals with radially symmetric body plans . The term Radiata is no longer accepted, as it united several different groupings of animals that do not form
90-669: Is not a worm at all, but a skin fungus. Lobopodians are an informal grouping of extinct panarthropods from the Cambrian to the Carboniferous that are often called worms or "worm-like animals" despite having had legs in the form of stubby lobopods. Likewise, the extant Onychophora are sometimes called velvet worms despite possessing stubby legs. Wyrm was the Old English term for carnivorous reptiles ("serpents") and mythical dragons . "Worm" has also been used as
105-459: Is sometimes used to refer to parasitic worms. The term is more commonly used in medicine , and usually refers to roundworms and tapeworms. In taxonomy, "worm" refers to an obsolete grouping, Vermes , used by Carl Linnaeus and Jean-Baptiste Lamarck for all non- arthropod invertebrate animals , now seen to be polyphyletic . In 1758, Linnaeus created the first hierarchical classification in his Systema Naturae . In his original scheme,
120-467: The Nematoda (roundworms) and Cestoda (tapeworms). Hence, " helminthology " is the study of parasitic worms. When a human or an animal, such as a dog or horse, is said to "have worms", it means that it is infested with parasitic worms , typically roundworms or tapeworms . Deworming is a method to kill off the worms that have infected a human or animal by giving anthelmintic drugs. " Ringworm "
135-411: The Old English word wyrm . Most animals called "worms" are invertebrates , but the term is also used for the amphibian caecilians and the slowworm Anguis , a legless burrowing lizard . Invertebrate animals commonly called "worms" include annelids , nematodes , flatworms , nemerteans , chaetognaths , priapulids , and insect larvae such as grubs and maggots . The term " helminth "
150-549: The 13th century, worms were recognized in Europe as part of the category of reptiles that consisted of a miscellany of egg-laying creatures, including "snakes, various fantastic monsters, lizards, assorted amphibians", as recorded by Vincent of Beauvais in his Mirror of Nature . In everyday language, the term worm is also applied to various other living forms such as larvae , insects , millipedes , centipedes , shipworms (teredo worms), or even some vertebrates (creatures with
165-667: The African giant earthworm, Microchaetus rappi ; and 58 metres (190 ft) for the marine nemertean worm (bootlace worm), Lineus longissimus . Various types of worm occupy a small variety of parasitic niches, living inside the bodies of other animals. Free-living worm species do not live on land but instead live in marine or freshwater environments or underground by burrowing. In biology, "worm" refers to an obsolete taxon , Vermes , used by Carolus Linnaeus and Jean-Baptiste Lamarck for all non- arthropod invertebrate animals , now seen to be paraphyletic . The name stems from
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#1732782560121180-471: The Radiata ( Zoophytes ). Thomas Cavalier-Smith , in 1983, redefined Radiata as a subkingdom consisting of Myxozoa , Placozoa , Cnidaria and Ctenophora. Lynn Margulis and K. V. Schwartz later redefined Radiata in their Five Kingdom classification, this time including only Cnidaria and Ctenophora. This definition is similar to the historical descriptor Coelenterata , which has also been proposed as
195-551: The animals were one of three kingdoms, divided into the classes of Vermes , Insecta , Pisces , Amphibia , Aves , and Mammalia . 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) and split
210-452: The cnidarian class Anthozoa are bilaterally symmetric (For example, Nematostella vectensis ). It has been suggested that bilateral symmetry may have evolved before the split between Cnidaria and Bilateria, and that the radially symmetrical cnidarians have secondarily evolved radial symmetry, meaning the bilaterality in cnidarian species like N. vectensis has a primary origin. The differing definitions assigned by zoologists are listed in
225-442: The group into three new phyla, worms, echinoderms, and polyps (which contained corals and jellyfish). By 1809, in his Philosophie Zoologique , Lamarck had created 9 phyla apart from vertebrates (where he still had 4 phyla: mammals, birds, reptiles, and fish) and molluscs, namely cirripedes , annelids, crustaceans, arachnids, insects, worms, radiates , polyps, and infusorians . Chordates are remarkably wormlike by ancestry. In
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