Eutardigrada are a class of

tardigrade Tardigrades (), known colloquially as water bears or moss piglets, are a phylum of eight-legged segmented micro-animals. They were first described by the German zoologist Johann August Ephraim Goeze in 1773, who called them Kleiner Wasserbär ...

s (Tardigrada) without lateral appendices. Primarily freshwater bound, some species have secondarily gained the ability to live in marine environments (''

Halobiotus ''Halobiotus'' is a genus of water bear or moss piglet, a tardigrade in the class Eutardigrada Eutardigrada are a class of tardigrades (Tardigrada) without lateral appendices. Primarily freshwater bound, some species have secondarily gained th ...

''). By

cryptobiosis Cryptobiosis or anabiosis is a metabolic state of life entered by an organism in response to adverse environmental conditions such as desiccation, freezing, and oxygen deficiency. In the cryptobiotic state, all measurable metabolic processes stop ...

many species are able to live temporarily in very dry environments. More than 700 species have been described. The order Apochela consists of only one family,

Milnesiidae Milnesiidae is a family of tardigrade Tardigrades (), known colloquially as water bears or moss piglets, are a phylum of eight-legged segmented micro-animals. They were first described by the German zoologist Johann August Ephraim Goeze i ...

, with two genera: ''

Milnesium ''Milnesium'' is a genus of tardigrades. It is rather common, being found in a wide variety of habitats across the world. It has a fossil record extending back to the Cretaceous, the oldest species found so far (''M. swolenskyi'') is known from T ...

'' and ''

Limmenius ''Limmenius'' is a genus of tardigrades with one species, ''Limmenius porcellus''. References External links * A specimen of ''Limmenius porcellus''at the Museum of New Zealand The Museum of New Zealand Te Papa Tongarewa is New Zealand's ...

''. ''

Milnesium tardigradum ''Milnesium tardigradum'' is a cosmopolitan species of tardigrade that can be found in a diverse range of environments. It has also been found in the sea around Antarctica. ''M. tardigradum'' was described by Louis Michel François Doyère in 184 ...

'' can be found worldwide and is one of the biggest species among tardigrades (up to 1.4 mm); similar-looking species have been found in

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

amber Amber is fossilized tree resin that has been appreciated for its color and natural beauty since Neolithic times. Much valued from antiquity to the present as a gemstone, amber is made into a variety of decorative objects."Amber" (2004). In Ma ...

. The mouth of this

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

has a wide opening, so the animal can eat

rotifer The rotifers (, from the Latin , "wheel", and , "bearing"), commonly called wheel animals or wheel animalcules, make up a phylum (Rotifera ) of microscopic and near-microscopic pseudocoelomate animals. They were first described by Rev. John H ...

s and larger

protist A protist () is any eukaryotic organism (that is, an organism whose cells contain a cell nucleus) that is not an animal, plant, or fungus. While it is likely that protists share a common ancestor (the last eukaryotic common ancestor), the exc ...

s. Other eutardigrades belong to the order Parachela.

References

External links

* *
Tardigrade taxa''Milnesium tardigradum'' (radiation experiments)
Protostome classes Extant Cretaceous first appearances {{tardigrade-stub