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''). 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 st ...

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, with two genera: '' Milnesium'' and '' Limmenius''. ''

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 1 ...

'' 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 ...

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 M ...

. 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 ...

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 e ...

s. Other eutardigrades belong to the order Parachela.

References

External links

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