Any of thousands of species of unrelated invertebrate animals that typically have a soft, slender, elongated body with no appendages. The major phyla are Platyhelminthes (flatworms), Annelida (annelids, or segmented worms), Nemertea (ribbon worms), Acanthocephala (spiny-headed worms), and Aschelminthes (nematodes and others). There are several minor phyla. Length ranges from microscopic (e.g., some aschelminths) to more than 100 ft (30 m) (some ribbon worms). Worms are found worldwide on land and in water. They may be parasitic or free-living and are important as soil conditioners, parasites, and a link in the food chain in all ecosystems. Seealso fluke, pinworm, polychaete, rotifer, tapeworm, tube worm.
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Any of about 90 species of free-living terrestrial invertebrates in the class Onychophora (sometimes considered a phylum). They are sometimes called velvet worms for their velvety skin. The common genus Peripatus occurs in the West Indies, Central America, and northern South America. Onychophorans are slender and segmented; each segment has a pair of short legs. Species range from 0.6 to 6 in. (14–150 mm) long. They live in humid, hidden spots: in forest litter, wood crevices, termite nests, or the soil, sometimes to a depth of more than 3 ft (1 m). They use their jaws to open captured prey (often small insects) and suck out the juices.
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Any of numerous species of sedentary, solitary or colonial, marine worms that spend their entire life in a tube made from special secretions or from sand grains glued together. Found worldwide, tube worms range from less than an inch (25 mm) to more than 20 ft (6 m) long. The bottom of the tube is attached to the seafloor; the mouth and tentacles are at the upper, open end. The worm breathes through gills, the tentacles, or the body wall. The tentacles, variously arranged, are used to filter-feed aquatic plants and animals. Tube worms occur in the annelid class Polychaeta and in the phyla Phoronida and Pogonophora. Many, mostly unnamed, forms live in deep-ocean vent communities.
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Body plan of an earthworm. Partitions (septa) divide the body cavity (coelom) into more than 100 elipsis
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Nematode (Ascaris lumbricoides)
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Larva of any member of a large, widespread group (mostly in the family Geometridae, with some in the family Noctuidae) of moths. Loopers move in a characteristic “inching” or “looping” gait by extending the front part of the body and bringing the rear up to meet it. Resembling twigs or leaf stems, they feed on foliage, and can seriously damage or destroy trees.
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Distinctive green, white-lined larva, or caterpillar (Trichoplusia ni), of the owlet moth family (Noctuidae). Like other loopers, it moves in an “inching” motion. It is an economic pest of cabbages and associated crops, particularly in the U.S. and Europe. The adults, known as Ni moths, migrate considerable distances. They are mottled brown with a pale Y-shaped mark on each forewing. The typical adult wingspan is about 1 in. (25 mm).
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Any of about 5,400 species of marine worms of the annelid class Polychaeta, having a segmented body with many setae (bristles) on each segment. Species, often brightly coloured, range from less than 1 in. (2.5 cm) to about 10 ft (3 m) long. Most body segments bear two bristly parapodia (lobelike outgrowths). The head has short sensory projections and tentacles. Adults may be free-swimming or sedentary; larvae are free-swimming. Found worldwide, polychaetes are important for turning over sediment on the ocean bottom. One species, the bloodworm, is a popular saltwater fish bait. Seealso tube worm.
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Any of about 250–300 species (class Nematomorpha, or Gordiacea; phylum Aschelminthes) of long, thin worms. The young are parasites in arthropods; the adults are free-living in the sea or in freshwater. The hairlike body sometimes grows to a length of about 39 in. (1 m).
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Nematode (Dracunculus medinensis) that is a common parasite of humans and other mammals in tropical Asia and Africa and has been introduced into the West Indies and tropical South America. The female grows to 20–48 in. (50–120 cm) long; the male, which dies upon mating, is only about 0.5–1.1 in. (12–29 mm) long. Both sexes live in the connective tissue of the host animal. Humans become infected when they drink water containing tiny crustaceans (e.g., copepods) that have eaten guinea-worm larvae. The disease the guinea worm carries, called dracunculiasis, can be extremely debilitating and painful.
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Any of a group of parasitic nematodes that usually require two hosts to complete the life cycle: an arthropod and another animal, which is bitten by the arthropod. The female worm produces large numbers of microscopic, active embryos, called microfilariae, that pass into the bloodstream of the primary host. These enter the body of an insect when it bites the infected animal; within the insect the microfilariae grow into larvae, which are passed to an animal the insect bites, where they complete their growth. Seealso heartworm.
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It is 13 cm long and weighs 13 g. It is relatively plain with olive-brown upperparts and light-coloured underparts, but has black and light brown stripes on its head. It has a slim pointed bill and pink legs. In immature birds, the head stripes are brownish.
This bird breeds in dense deciduous forests in the eastern United States, usually on wooded slopes. The nest is an open cup placed on the ground, hidden among dead leaves. The female lays 4 or 5 eggs. Both parents feed the young; they may try to distract predators near the nest by pretending to be injured.
Worm-eating Warblers eat insects, usually searching in dead leaves or bark on trees and shrubs, also picking through dead leaves on the forest floor. Despite their name, they rarely if ever eat earthworms.
The male's song is a short high-pitched trill. This bird's call is a chip or tseet.
Worm-eating Warblers have disappeared from some parts of their range due to habitat loss. They are vulnerable to nest parasitism by the Brown-headed Cowbird where forests are fragmented.