The Gnathiidae are a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

isopod Isopoda is an Order (biology), order of crustaceans. Members of this group are called isopods and include both Aquatic animal, aquatic species and Terrestrial animal, terrestrial species such as woodlice. All have rigid, segmented exoskeletons ...

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

s. They occur in a wide range of depths, from the

littoral zone The littoral zone, also called litoral or nearshore, is the part of a sea, lake, or river that is close to the shore. In coastal ecology, the littoral zone includes the intertidal zone extending from the high water mark (which is rarely flood ...

to the deep sea. The adults are associated with

sponge Sponges or sea sponges are primarily marine invertebrates of the animal phylum Porifera (; meaning 'pore bearer'), a basal clade and a sister taxon of the diploblasts. They are sessile filter feeders that are bound to the seabed, and a ...

s and may not feed. The juvenile form is known as a 'praniza', and it is a temporary

parasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...

of marine fish. These forms are not larvae; ''Gnathiidae'' instead become parasitic during the manca stage. Mancae of the ''Gnathiidae'' closely resemble the adult form, however they lack the final pair of

pereiopod The anatomy of a decapod consists of 20 body segments grouped into two main body parts: the cephalothorax and the pleon (abdomen). Each segment – often called a somite – may possess one pair of appendages, although in various groups these m ...

s. Taxonomy in the family relies on male characters, such that females and juveniles cannot be reliably identified. The family contains 182 species, divided among the following genera: *'' Afrignathia'' Hadfield & Smit, 2008 *'' Bathygnathia'' Dollfus, 1901 *'' Bythognathia'' Camp, 1988 *'' Caecognathia'' Dollfus, 1901 *'' Elaphognathia'' Monod, 1926 *'' Euneognathia'' Stebbing, 1893 *'' Gibbagnathia'' Cohen & Poore, 1994 *'' Gnathia'' Leach, 1814 *'' Monodgnathia'' Cohen & Poore, 1994 *'' Paragnathia'' Omer-Cooper & Omer-Cooper, 1916 *'' Tenerognathia'' Tanaka, 2005 *'' Thaumastognathia'' Monod, 1926 The extinct Jurassic genus '' Urda'' is thought to represent a stem-group to the family, and is suggested to have had a similar parasitic lifestyle.

References

External links

Gnathiidae
Australian Isopoda Cymothoida Taxa named by William Elford Leach Parasitic crustaceans Isopod families {{parasitic animal-stub