The order Ascaridida includes several families of

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...

roundworms The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-parasitic nematodes also known as eelworms. They are a diverse animal phylum inhabiting a broa ...

with three "lips" on the anterior end. They were formerly placed in the subclass

Rhabditia Subclass Rhabditia is mostly composed of parasitic nematodes (particularly in the Strongylida), though there are some free-living species as well (particularly in the Rhabditida). Phasmids (posterior sensory structures) are well-developed, whil ...

by some, but morphological and DNA sequence data rather unequivocally assign them to the

Spiruria Subclass Spiruria comprises mostly parasitic secernentean nematodes. In an alternate classification, they are treated as suborder Spirurina, with the orders listed here being ranked as infraorders. The Ascaridida and the Oxyurida, which include ...

. The

Oxyurida Oxyurida is an order of nematode worms of the class Secernentea. It consists of four families, one of which contains the human pinworm (''Enterobius vermicularis''). Species Notable species include: * ''Enterobius vermicularis'', the human ...

and Rhigonematida are occasionally placed in the Ascaridida as superfamily Oxyuroidea, but while they seem indeed to be Spiruria, they are not as close to ''

Ascaris ''Ascaris'' is a genus of parasitic nematode worms known as the "small intestinal roundworms", which is a type of parasitic worm. One species, '' Ascaris lumbricoides'', affects humans and causes the disease ascariasis. Another species, ''Asc ...

'' as such a treatment would place them.

Tree of Life Web Project The Tree of Life Web Project is an Internet project providing information about the diversity and phylogeny of life on Earth. This collaborative peer reviewed project began in 1995, and is written by biologists from around the world. The site ...

(ToL) (2002)
Nematoda
Version of 2002-JAN-01. Retrieved 2008-NOV-02. These "

worm Worms are many different distantly related bilateral animals that typically have a long cylindrical tube-like body, no limbs, and no eyes (though not always). Worms vary in size from microscopic to over in length for marine polychaete wo ...

s" contain a number of important

parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

s of humans and

domestic animal This page gives a list of domesticated animals, also including a list of domestication of animals, animals which are or may be currently undergoing the process of domestication and animals that have an extensive relationship with humans beyond simp ...

s. Important

families Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Ideal ...

include: * The

Anisakidae The Anisakidae are a family of intestinal nematodes (roundworms). The larvae of these worms can cause anisakiasis when ingested by humans, in raw or insufficiently cooked fish. Anisakidae worms can infect many species of fish, birds, mammals and ...

are also called the "

marine mammal Marine mammals are aquatic mammals that rely on the ocean and other marine ecosystems for their existence. They include animals such as seals, whales, manatees, sea otters and polar bears. They are an informal group, unified only by their ...

ascarids". The larvae of these worms cause

anisakiasis ''Anisakis'' (a·nuh·saa·keez) is a genus of parasitic nematodes that have life cycles involving fish and marine mammals. They are infective to humans and cause anisakiasis. People who produce immunoglobulin E in response to this parasite may ...

when ingested by humans in raw or insufficiently cooked fish, but do not reproduce in humans. * The

Ascarididae The Ascarididae are a family of the large intestinal nematoda, roundworms. Members of the family are intestinal parasites, infecting all class (biology), classes of vertebrates. It includes a number of genus, genera,Anderson RC (2000)''Nematode Pa ...

include the giant intestinal roundworms (''Ascaris'' spp.). * The Cosmocercidae include taxa that parasitize certain amphibians. * The Toxocaridae include parasites of

canids Canidae (; from Latin, ''canis'', " dog") is a biological family of dog-like carnivorans, colloquially referred to as dogs, and constitutes a clade. A member of this family is also called a canid (). There are three subfamilies found within ...

felid Felidae () is the family of mammals in the order Carnivora colloquially referred to as cats, and constitutes a clade. A member of this family is also called a felid (). The term "cat" refers both to felids in general and specifically to the dom ...

s, and

raccoon The raccoon ( or , ''Procyon lotor''), sometimes called the common raccoon to distinguish it from other species, is a mammal native to North America. It is the largest of the procyonid family, having a body length of , and a body weight of ...

s, but can unsuccessfully parasitize humans and cause

visceral larva migrans Visceral larva migrans (VLM) is a condition in humans caused by the migratory larvae of certain nematodes, humans being a dead-end host, and was first reported in 1952. Nematodes causing such zoonotic infections are ''Baylisascaris procyonis'', '' ...

. * The Ascaridiidae include roundworms of birds. These all belong in the superfamily Ascaridoidea.

References

Nematode orders {{parasitic animal-stub