The Enchytraeidae are a microdrile oligochaete

Oligochaeta

Oligochaeta is a subclass of animals in the biological phylum Annelida, which is made up of many types of aquatic and terrestrial worms, and this includes all of the various earthworms...

 family. They resemble small earthworm

Earthworm

Earthworm is the common name for the largest members of Oligochaeta in the phylum Annelida. In classical systems they were placed in the order Opisthopora, on the basis of the male pores opening posterior to the female pores, even though the internal male segments are anterior to the female...

s and include both terrestrial species known as potworms that live in highly organic terrestrial

Terrestrial

Terrestrial refers to things related to land or the planet Earth.Terrestrial may also refer to:* Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on or near the ground, as opposed to in trees etc.** A fishing fly that simulates the...

 environments, as well as some that are marine

Marine (ocean)

Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...

. The peculiar genus Mesenchytraeus is known as "ice worms", as they live in glacier

Glacier

A glacier is a large persistent body of ice that forms where the accumulation of snow exceeds its ablation over many years, often centuries. At least 0.1 km² in area and 50 m thick, but often much larger, a glacier slowly deforms and flows due to stresses induced by its weight...

s and will die if exposed to temperatures a few degrees above freezing. Apart from these, the best-known species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 is probably the Grindal Worm (Enchytraeus buchholzi), which is commercially bred as aquarium

Aquarium

An aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...

 fish food.

Selected genera

Enchytraeidae genera

Genera

Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...

 include:

• Achaeta Vejdovský, 1878
• Archienchytraeus Eisen, 1878 (nomen dubium
  Nomen dubium
  In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
  
  )
• Cernosvitoviella Nielsen & Christensen, 1959
• Christensenidrilus Dózsa-Farkas & Convey, 1998 (= Christensenia Dózsa-Farkas & Convey, 1997 (non Brinck 1945: preoccupied))
• Cognettia Nielsen & Christensen, 1959
• Enchytraeina Bülow, 1957
• Enchytraeus
  Enchytraeus
  The genus Enchytraeus includes about 40 species of annelid worms. The term white worm is often used for all of the species in general, but specifically it is E. albidus which is named the white worm. This species is used as fish food by aquarium enthusiasts. E. buchholzi is known as the Grindal worm...
  
  
• Epitelphusa Drago, 1887
• Fridericia Michaelsen, 1889
• Grania
  Grania
  Grania is a genus of marine worms in the class Clitellata. They are found at many depths in sands throughout the world. They are generally about in length and mostly colorless or white, though Grania colorata, a recently discovered species found in the Great Barrier Reef, is green. 71 species in...
  
  
• Hemifridericia Nielsen & Christensen, 1949
• Henlea Michaelsen, 1889 (= Henleanella)
• Lumbricillus Ørsted, 1844 (= Enchytraeoides, Pachydrilus)
• Marionina Michaelsen in Pfeffer, 1890 (= Marionia Michaelsen, 1889 (non Vayssière, 1877: preoccupied
  Marionia
  Marionia is a genus of sea slugs, specifically dendronotid nudibranchs, marine gastropod molluscs in the family Tritoniidae.- Species :Species within the genus Marionia include:* Marionia bathycarolinensis Smith & Gosliner, 2005...
  
  ), Michaelsena, Parenchytraeus)
• Mesenchytraeus – ice worms
• Neoenchytraeus Eisen, 1878
• Randidrilus Coates & Erséus, 1985
• Stephensoniella Cernosvitov, 1934