A worm is an elongated, soft-bodied, land-dwelling invertebrate. An invertebrate is an Animal lacking a Vertebral column. The group includes 98% of all animal Species — all animals except those in the Chordate Worm is a common name for various species that belong to different clades of animals--that is they are unrelated to each other. For Wikipedia aspects see WikipediaNaming conventions (common names, WikipediaNaming conventions, and WikipediaStyle manual. A clade is a taxonomic group comprising a single Common ancestor and all the descendants of that ancestor Animals which are commonly called worms include species of annelids, insects (their immature larva stage), and flatworms. The annelids, collectively called Annelida (from Latin anellus "little ring" are a large phylum of Animals comprising Insects ( Class Insecta) are a major group of Arthropods and the most diverse group of Animals on the Earth with over a million described A larva ( Latin; plural larvae) is a juvenile form of Animal with indirect development, undergoing Metamorphosis (for example The flatworms (Phylum Platyhelminthes from the Greek πλατύ platy, meaning "flat" and ἕλμινς (root ἑλμινθ- helminth- Many marine and freshwater species, which are usually seen only by professional biologists, are recognized as "worms". Worms commonly are seen on the sidewalk after a rainstorm, and often die of drying out or being trampled on by humans.

Contents 1 Distribution and habitat 2 Classification 3 Characteristics 4 See also

Distribution and habitat

There are at least 1,000,000 species of worms. The American Robin, Turdus migratorius, is a migratory Songbird of the thrush family They are found almost all over the world. Worms are universal in distribution, occurring in marine, freshwater, and terrestrial habitats. Some worms living in the ground help to condition the soil (e. g. , annelids, aschelminths). The annelids, collectively called Annelida (from Latin anellus "little ring" are a large phylum of Animals comprising The Aschelminthes (also known as Aeschelminthes, Nemathelminthes, or Pseudocoelomata) closely associated with the Platyhelminthes, are an obsolete Many thrive as parasites of plants (e. Parasitism is a type of symbiotic relationship between Organisms of different Species. g. , aschelminths) and animals, including humans (e. g. , platyhelminths, aschelminths). The flatworms (Phylum Platyhelminthes from the Greek πλατύ platy, meaning "flat" and ἕλμινς (root ἑλμινθ- helminth- Several other worms may be free-living, or nonparasitic. There are worms that live in freshwater, seawater, and even on the seashore. Freshwater is a word that refers to bodies of water such as Ponds lakes rivers and streams containing low concentrations of dissolved Salts and other Total dissolved Seawater is Water from a Sea or Ocean. On average seawater in the world's oceans has a Salinity of about 3 Ecologically, worms form an important link in the food chains in virtually all the ecosystems of the world. Food chains, also called food networks and/or trophic networks, describe the feeding relationships between species within an Ecosystem. An ecosystem is a natural unit consisting of all plants animals and micro-organisms( Biotic factors in an area functioning together with all of the non-living physical (

Worms may also be called helminths, particularly in medical terminology when referring to parasitic worms, especially the Nematoda (roundworms) and Cestoda (tapeworms). Hence "helminthology" is the study of parasitic worms. Helminthology is the study of Worms and especially Parasitic worms This field deals with the study of their Taxonomy and the effect on their hosts When an animal, such as a dog, is said to "have worms", it means that it is infested with parasitic worms, typically roundworms or tapeworms.

Classification

In everyday language, the term worm is also applied to various other living forms such as larvae, insects, centipedes, shipworms (teredo worms), or even some vertebrates (creatures with a backbone) such as blindworms and caecilians. A larva ( Latin; plural larvae) is a juvenile form of Animal with indirect development, undergoing Metamorphosis (for example Insects ( Class Insecta) are a major group of Arthropods and the most diverse group of Animals on the Earth with over a million described Centipedes (from Latin prefix centi-, "hundred" and Greek ποδός podos, " Foot " are Shipworms are not worms at all but rather a group of unusual saltwater clams with very reduced shells notorious for boring into (and eventually destroying wooden structures which Anguis fragilis (the slow worm, slow-worm, slowworm, blindworm or blind worm) is a limbless Reptile native Apoda redirects here For the Moth Genus, see Apoda (moth. For the bishop of Carthage see Caecilianus. Worms can be divided into several groups,

• The first of these includes the flatworms. The flatworms (Phylum Platyhelminthes from the Greek πλατύ platy, meaning "flat" and ἕλμινς (root ἑλμινθ- helminth- This phylum is called Platyhelminthes. They have a flat, ribbon- or leaf-shaped body with a pair of eyes at the front. Some are parasites.
• The second group contains the threadworms, roundworms, and hookworms. The pinworm (Genus Enterobius) also known as threadworm is a Parasitic Roundworm of the phylum Nematoda. The nematodes or roundworms ( Phylum Nematoda from Greek (nema "thread" + -ode "like" are one of the most common The hookworm is a parasitic Nematode worm that lives in the Small intestine of its host which may be a Mammal such as a Dog, This phylum is called Nemotoda. Threadworms may be microscopic, such as the vinegar eelworm, or more than 1 meter (3 feet) long. They are found in damp earth, moss, decaying substances, fresh water, or salt water. Some roundworms are also parasites. The Guinea worm, for example, gets under the skin of the feet and legs of people living in tropical countries. Dracunculiasis, more commonly known as Guinea worm disease ( GWD) or Medina Worm, is a parasitic Infection caused by the The Tropics are centered on the Equator and limited in Latitude by the Tropic of Cancer in the northern hemisphere at approximately 23°26' (23
• The third group consists of the segmented worms, with bodies divided into segments, or rings. This phylum is called Annelida. Among these are the earthworms and the bristle worms of the sea. Earthworm is the usual name for the largest members of Oligochaeta (which is either a class or subclass depending on the author in the phylum Annelida In classical The Polychaeta or polychaetes are a class of Annelid worms generally marine

There are hundreds of thousands of species that live in a wide variety of habitats other than soil. In Biology, a species is one of the basic units of Biological classification and a Taxonomic rank. Soil, often typeset as SOiL, is a four piece rock band from Chicago Illinois United States founded by Shaun Glass Tom Schofield Tim King and Adam Zadel Over time this broad definition narrowed to the modern definition, although this still includes several different animal groups. Major phyla that include worms include:

• Acanthocephala (spiny-headed worms)
• Ancylostoma (hook worms)
• Annelida (segmented worms)
• Cestoda (tapeworm)
• Chaetognatha (arrow worms)
• Ectoprocta (goblet worms)
• Gnathostomulid (jaw worms)
• Hemichordata (acorn/tongue worms)
• Kinorhyncha (spiny-crown worms)
• Nematoda (roundworms)
• Nematomorpha (horsehair worms)
• Nemertea (ribbonworms)
• Onychophora (velvet worms)
• Phoronida (horseshoe worms)
• Platyhelminthes (flatworms)
• Priapulida (phallus worms)
• Sipuncula (peanut worms)

Worms have sex with penises and vaginas. Earthworm is the usual name for the largest members of Oligochaeta (which is either a class or subclass depending on the author in the phylum Annelida In classical The Acanthocephala ( Greek ακανθος akanthos, thorn + κεφαλη kephale, head is a phylum of Parasitic worms known as Ancylostoma is a genus that includes some species of Hookworm. The annelids, collectively called Annelida (from Latin anellus "little ring" are a large phylum of Animals comprising Tapeworm is also an older name for a type of Computer virus. Cestoda is a class of Parasitic Flatworms commonly called Chaetognatha is a phylum of predatory marine worms that are a major component of Plankton worldwide Bryozoans are tiny colonial Animals that generally build stony Skeletons of Calcium carbonate, superficially similar to Coral (although some Gnathostomulids, or jaw worms, are a small phylum of nearly microscopic marine Animals Most measure between 0 Hemichordata is a phylum of worm-shaped marine Deuterostome Animals generally considered the sister group of the Echinoderms They date Kinorhyncha (Gr κίνηω kīneō 'move' + ρυνχος rhynchos 'snout' is a phylum of small (1 mm or less marine pseudocoelomate The nematodes or roundworms ( Phylum Nematoda from Greek (nema "thread" + -ode "like" are one of the most common Nematomorpha (sometimes called Gordiacea, and commonly known as Horsehair worms or Gordian worms) are a Phylum of Parasitic Nemertea is a Phylum of Invertebrate Animals also known as ribbon worms or proboscis worms   The velvet worms ( Onychophora — literally "claw bearers" form a Clade within the Ecdysozoa and can be simply described as " Worms Phoronids (' Phoronida') commonly known as horseshoe worms, are a relatively small animal Phylum: twenty species are known in two genera The flatworms (Phylum Platyhelminthes from the Greek πλατύ platy, meaning "flat" and ἕλμινς (root ἑλμινθ- helminth- Priapulida ( priapulid worms or penis worms, from Gr πριάπος priāpos ' Priapus ' + Lat The Sipuncula or Sipunculida, sipunculid worms or peanut worms, are a phylum containing 144-320 Species (estimates vary of bilaterally

The most common worm is the earthworm, a member of phylum Annelida. Earthworm is the usual name for the largest members of Oligochaeta (which is either a class or subclass depending on the author in the phylum Annelida In classical A phylum ( Plural: phyla) is a Taxonomic rank between Kingdom and above Class. The annelids, collectively called Annelida (from Latin anellus "little ring" are a large phylum of Animals comprising Earthworms in general have been around for 120 million years, evolving during the time of the dinosaurs. They enrich and aerate the soil; Charles Darwin found that worms turn over the top six inches (15 cm) of topsoil every 20 years. Charles Robert Darwin (February 12 1809 &ndash April 19 1882 was an English naturalist, who realised and demonstrated that all Species of life They lack a brain but have nerve centers (called ganglia); they also lack eyes but can sense light with photoreceptors. An ocellus (plural ocelli) is a type of Photoreceptor organ in animals Worms are hermaphrodites (both sexes in one animal) but can cross fertilize. A hermaphrodite is an organism having both male and female reproductive organs

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, or silkworm. Insects ( Class Insecta) are a major group of Arthropods and the most diverse group of Animals on the Earth with over a million described A larva ( Latin; plural larvae) is a juvenile form of Animal with indirect development, undergoing Metamorphosis (for example A railroad worm is a Larva or Larviform female adult of a Beetle of the genus Phrixothrix in the family Phengodidae A Woodworm is not a specific species. It is the Larval stage of certain Wood-boring beetles including Ambrosia beetles ( Platypodidae Glowworm (or glow-worm) is the common name for various different groups of insect Larva and adult Larviform females which glow through Midges comprise many kinds of very small two-winged flies The term does not encapsulate a well-defined taxonomic group but includes animals in several families of Nematoceran

Worms may also be called helminths, particularly in medical terminology when referring to parasitic worms, especially the Nematoda (roundworms) and Cestoda (tapeworms). Medicine is the art and science of healing It encompasses a range of Health care practices evolved to maintain and restore Human Health by the See also Parasitic worm (disambiguation Parasitic worms or helminths are a division of eukaroytic Parasites that unlike external parasites such The nematodes or roundworms ( Phylum Nematoda from Greek (nema "thread" + -ode "like" are one of the most common Tapeworm is also an older name for a type of Computer virus. Cestoda is a class of Parasitic Flatworms commonly called Hence "helminthology" is the study of parasitic worms. Helminthology is the study of Worms and especially Parasitic worms This field deals with the study of their Taxonomy and the effect on their hosts When an animal, such as a dog, is said to "have worms", it means that it is infested with parasitic worms, typically roundworms or tapeworms. The dog ( Canis lupus familiaris) is a domesticated Subspecies of the gray wolf, a Mammal of the Canidae family of the order The nematodes or roundworms ( Phylum Nematoda from Greek (nema "thread" + -ode "like" are one of the most common Tapeworm is also an older name for a type of Computer virus. Cestoda is a class of Parasitic Flatworms commonly called

"Ringworm" is not a worm at all, but a skin fungus. Ringworm (also called serpigo) is an infection of the skin characterized by a reddish to brownish raised or bumpy patch of skin that may be lighter in the center

Characteristics

Worms usually have a cylindrical, flattened, or leaf-like body shape and are often without any true limbs or appendages. Nematomorpha (sometimes called Gordiacea, and commonly known as Horsehair worms or Gordian worms) are a Phylum of Parasitic Instead, they may have bristles or fins that help them move. Many worms have sense organs that can detect environmental change. A few may even have light-sensing organs. Worms vary in size from less than 1 mm (0. 04 inch) in certain aschelminths to more than 30 m (100 feet) in certain ribbon worms. The Aschelminthes (also known as Aeschelminthes, Nemathelminthes, or Pseudocoelomata) closely associated with the Platyhelminthes, are an obsolete

Some worms reproduce sexually. Hermaphroditism, the condition in which a single individual possesses both male and female reproductive parts, is common in many groups of worms. A hermaphrodite is an organism having both male and female reproductive organs Asexual reproduction, whereby new individuals develop from the body cells of another, also occurs in some worms. Asexual reproduction is a form of reproduction which does not involve Meiosis, Ploidy reduction or Fertilization.

Worm species differ in their abilities to move about on their own. In Biology, a species is one of the basic units of Biological classification and a Taxonomic rank. Many species have bodies with no major muscles, and cannot move on their own — they must be moved by forces or other animals in their environment. Many other species have bodies with major muscles and can move on their own; they are a type of muscular hydrostat. A muscular hydrostat is a biological structure found in Animals It is used to manipulate items (including food or to move its host about and consists mainly of Muscles Many species of worms are decomposers; they break down dead plants and animals to return nutrients to the soil.

See also

• Worm cast
• Worm charming

A worm cast or vermicast is a structure created by Worms typically on Soils such as those on Beaches that gives the appearance of multiple worms Worm charming, worm grunting, and worm fiddling are methods of attracting Earthworms from the ground

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