The

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean gro ...

order Tanaidacea (known as tanaids) make up a minor group within the class

Malacostraca Malacostraca (from New Latin; ) is the largest of the six classes of crustaceans, containing about 40,000 living species, divided among 16 orders. Its members, the malacostracans, display a great diversity of body forms and include crabs, lobs ...

. There are about 940 species in this order.

Description

Tanaids are small, shrimp-like creatures ranging from in adult size, with most species being from . Their carapace covers the first two segments of the

thorax The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the ...

. There are three pairs of limbs on the thorax; a small pair of

maxilliped An appendage (or outgrowth) is an external body part, or natural prolongation, that protrudes from an organism's body. In arthropods, an appendage refers to any of the homologous body parts that may extend from a body segment, including ant ...

s, a pair of large clawed gnathopods, and a pair of

pereiopod The decapod (crustaceans such as a crab, lobster, shrimp or prawn) is made up of 20 body segments grouped into two main body parts: the cephalothorax and the pleon (abdomen). Each segment may possess one pair of appendages, although in various ...

s adapted for burrowing into the mud. Unusually among crustaceans, the remaining six thoracic segments have no limbs at all, but each of the first five

abdominal The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso ...

segments normally carry

pleopod The decapod (crustaceans such as a crab, lobster, shrimp or prawn) is made up of 20 body segments grouped into two main body parts: the cephalothorax and the pleon (abdomen). Each segment may possess one pair of appendages, although in various ...

s. The final segment is fused with the

telson The telson () is the posterior-most division of the body of an arthropod. Depending on the definition, the telson is either considered to be the final segment of the arthropod body, or an additional division that is not a true segment on accou ...

and carries a pair of

uropod Uropods are posterior appendages found on a wide variety of crustaceans. They typically have functions in locomotion. Definition Uropods are often defined as the appendages of the last body segment of a crustacean. An alternative definition sugge ...

s. The

gill A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they ar ...

s lie on the inner surface of the carapace. The thoracic limbs wash water towards the mouth, filtering out small particles of food with the mouthparts or maxillipeds. Some species actively hunt prey, either as their only food source, or in combination with filter feeding.

Habitat

Most are marine, but some are also found in

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does in ...

coastal

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environme ...

. The majority of species are bottom-dwellers in shallow water environments, but a few live in very deep water, exceeding for some species . In some deep sea environment, they represent the most abundant and diverse fauna to be found.

Life cycle

Tanaids do not undergo a true planktonic stage. The early developmental period is spent while young are within the marsupium of the mother. Subsequently, post-larvae, called mancas, emerge as

epibenthic Benthos (), also known as benthon, is the community of organisms that live on, in, or near the bottom of a sea, river, lake, or stream, also known as the benthic zone.hermaphroditic In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes. Many taxonomic groups of animals (mostly invertebrates) do not have se ...

Taxonomy

The order Tanaidacea is divided into the following sub-orders, superfamilies and families: * Suborder Anthracocaridomorpha † *** Family Anthracocarididae † Brooks, 1962 emend. Schram, 1979 *** Family Niveotanaidae † Polz, 2005 * Suborder Apseudomorpha ** Superfamily Apseudoidea Leach, 1814 (incl. former superfamily Jurapseudoidea) *** Family Apseudellidae Gutu, 1972 *** Family Apseudidae Leach, 1814 *** Family Eucryptocaridae Heard et al. 2020 *** Family

Gigantapseudidae ''Gigantapseudes'' is a genus of crustaceans belonging to the monotypic family Gigantapseudidae. The species of this genus are found in Malesia Malesia is a biogeographical region straddling the Equator and the boundaries of the Indomalaya ...

Kudinova-Pasternak, 1978 *** Family Jurapseudidae † Schram, Sieg & Malzahn, 1986 *** Family

Kalliapseudidae Kalliapseudidae is a family of crustaceans Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amph ...

Lang, 1956 *** Family Metapseudidae Lang, 1970 *** Family Numbakullidae Gutu & Heard, 2002 *** Family Ophthalmapseudidae Heard et al. 2020 *** Family

Pagurapseudidae Pagurapseudidae is a family of crustaceans in the order Tanaidacea. Like hermit crabs, they inhabit empty gastropod shells, but can be told apart from hermit crabs by the lack of a carapace A carapace is a Dorsum (biology), dorsal (upper) s ...

Lang, 1970 *** Family

Pagurapseudopsididae ''Pagurapseudopsis'' is a genus of crustaceans in the family (biology), family Pagurapseudidae, containing the following species: *''Pagurapseudopsis carinata'' (Bacescu, 1981) *''Pagurapseudopsis gracilipes'' Shiino, 1963 *''Pagurapseudopsis gym ...

Gutu, 2006 *** Family

Parapseudidae Parapseudidae is a family of crustaceans belonging to the order Tanaidacea. Subdivisions According to the World Register of Marine Species, the following subfamilies and genera are accepted within Paratanaoidea: * Pakistanapseudinae Gutu, 2008 ...

Gutu, 1981 *** Family Protoapseudoidae Heard et al. 2020 *** Family Sphaeromapseudidae Larsen, 2012 *** Family

Sphyrapodidae Sphyrapodidae is a family of crustaceans belonging to the order Tanaidacea. Genera: * ''Ansphyrapus'' Gutu, 2001 * ''Francapseudes'' Bacescu, 1981 * ''Kudinopasternakia'' Gutu, 1991 * ''Poligarida'' Bamber & Marshall, 2013 * ''Pseudosphyrapus'' ...

Gutu, 1980 *** Family

Tanzanapseudidae Tanzanapseudidae is a family of crustaceans belonging to the order Tanaidacea. Genera: * '' Acanthapseudes'' Roman, 1976 * '' Tanzanapseudes'' Bacescu, 1975 References {{Taxonbar, from=Q11848434 Tanaidacea ...

Bacescu, 1975 *** Family Whiteleggiidae Gutu, 1972 *** Genus '' Palaeotanais'' † Reiff, 1936 ** Superfamily Cretitanaoidea † Schram, Sieg, Malzahn, 1983 *** Family Cretitanaidae † Schram, Sieg & Malzahn, 1986 * Suborder Tanaidomorpha ** Superfamily Neotanaoidea Sieg, 1980 *** Family Neotanaidae Lang, 1956 ** Superfamily

Paratanaoidea Paratanaoidea is a superfamily of malacostracan crustacean. Families According to the World Register of Marine Species, the following families are accepted within Paratanaoidea: * Agathotanaidae Lang, 1971 * Akanthophoreidae Sieg, 1986 * ...

Lang, 1949 *** Family

Agathotanaidae ''Agathotanaidae'' is a family of crustaceans belonging to the order Tanaidacea. Genera: * '' Agathotanais'' Hansen, 1913 * '' Allodaposia'' Sieg, 1986 * '' Bunburia'' Jóźwiak & Jakiel, 2012 * '' Metagathotanais'' Bird & Holdich, 1988 * ...

Lang, 1971 *** Family

Akanthophoreidae Akanthophoreidae is a family of crustaceans belonging to the order Tanaidacea. Genera: * '' Akanthophoreus'' Sieg, 1986 * '' Brixia (crustacean)'' Jóźwiak, Drumm, Bird & Błażewicz, 2018 * '' Chauliopleona'' Dojiri & Sieg, 1997 * '' Mimicar ...

Sieg, 1986 *** Family Alavatanaidae † Vonk & Schram, 2007 *** Family Anarthruridae Lang, 1971 *** Family Colletteidae Larsen & Wilson, 2002 *** Family Cryptocopidae Sieg, 1977 *** Family Heterotanoididae Bird, 2012 *** Family

Leptocheliidae Leptocheliidae is a family of malacostracans in the order Tanaidacea. There are more than 30 genera and 140 described species in Leptocheliidae. Genera These 32 genera belong to the family Leptocheliidae: * '' Alloleptochelia'' Gutu, 2016 * ' ...

Lang, 1973 *** Family Leptognathiidae Sieg, 1976 *** Family Mirandotanaidae Blazewicz-Paszkowycz & Bamber, 2009 *** Family Nototanaidae Sieg, 1976 *** Family Paratanaidae Lang, 1949 *** Family

incertae sedis *** Family

Pseudotanaidae Pseudotanaidae is a family of crustaceans belonging to the order Tanaidacea. The family contains one subfamily, Pseudotanainae, which contains five genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of l ...

Sieg, 1976 *** Family Pseudozeuxidae Sieg, 1982 *** Family Tanaellidae Larsen & Wilson, 2002 *** Family Tanaissuidae Bird & Larsen, 2009 *** Family Tanaopsidae Błażewicz-Paszkowycz & Bamber, 2012 *** Family Teleotanaidae Bamber, 2008 *** Family

Typhlotanaidae Typhlotanaidae is a family of crustaceans belonging to the order Tanaidacea. Genera: * '' Antiplotanais'' Bamber, 2008 * '' Aremus'' Segadilha, Gellert & Błażewicz, 2018 * '' Dimorphognathia'' Sieg, 1986 * '' Larsenotanais'' Blazewicz-Paszko ...

Sieg, 1984 ** Superfamily Tanaidoidea Nobili, 1906 *** Family

Tanaididae Tanaididae is a family of malacostracans in the order Tanaidacea. There are about 19 genera and more than 90 described species in Tanaididae. Genera These 19 genera belong to the family Tanaididae: * ''Allotanais'' Shiino, 1978 * ''Anatanais'' ...

Nobili, 1906

References

External links

{{Authority control Malacostraca Crustacean orders