Tantulocarida is a highly specialised group of parasitic crustaceans that consists of about 33 species, treated as a class in superclass Multicrustacea. They are typically ectoparasites that infest copepods, isopods, tanaids, amphipods and ostracods.
Description
In the Tantulocarida, animals do not ever present eyes.
The tantulus larvae has a head with a ventral oral disc but no appendages, a six-segmented thorax with six pairs of legs, and a limbless abdomen consisting of one to six segments in addition to a telson.Multicellular Animals: Volume II: The Phylogenetic System of the Metazoa The larvae also possesses a cuticular stylet on the cephalon through which they can push a rootlet system for extraction of nutrients from a host. The rootlet system itself is a direct extension of the gut.
Body length Members of this subclass are minute – less than in length and have a dramatic reduction in body form compared to other crustaceans, with an unsegmented, sac-like thorax and a much reduced abdomen. One tantulocarid species, Tantulacus dieteri, is the world's smallest crustacean, with a total body length of only .
Life cycle
The tantulocarid life cycle is unique among crustaceans. The tantulus larva transforms directly from a non-feeding (lecithotrophic) and free-swimming organism into a parasite without any instars. When entering the parasitic stage much of the body, such as the muscles, degenerates, even if the body itself becomes bigger. As a parasite it is permanently attached to its host, and after piercing its host's cuticle with an unpaired stylet, a rootlet system used to absorb nutrients enters through the hole and grow into the host's tissue. The adult form develops inside the larva, and can become either a sac-like parthenogenetic female, or a fully developed free-living, non-feeding and sexually-reproducing male or female.Itoitantulus misophricola gen. et sp. nov.: First Record of Tantulocarida (Crustacea: Maxillopoda) in the North Pacific RegionAnatomy of the Tantulocarida: first results obtained using TEM and CLSM. Part I: tantulus larva - GfBS The eggs inside the parthenogenetic female are eventually released as fully developed tantulus larvae. The finding of what appears to be a benthic non-feeding nauplius larva suggests that eggs produced by sexual females hatch as nauplii instead of tantulus larvae. Both the parthenogenetic and sexual females are semelparous.Atlas of Crustacean Larvae
Classification Five families are recognised:
Basipodellidae Boxshall & Lincoln, 1983: Basipodella Becker, 1975 Hypertantulus Ohtsuka & Boxshall, 1998 Nipponotantulus Huys, Ohtsuka & Boxshall, 1994 Polynyapodella Huys, Møberg & Kristensen, 1997 Rimitantulus Huys & Conroy-Dalton, 1997 Serratotantulus Savchenko & Kolbasov, 2009 Stygotantulus Boxshall & Huys, 1989
Doryphallophoridae Huys, 1991: Doryphallophora Huys, 1990 Paradoryphallophora Ohtsuka & Boxshall, 1998
Microdajidae Boxshall & Lincoln, 1987: Microdajus Greve, 1965 Xenalytus Huys, 1991
Cumoniscidae Nierstrasz & Brender à Brandis, 1923 (formerly family Deoterthridae: Amphitantulus Boxshall & Vader, 1993 Aphotocentor Huys, 1991 Arcticotantulus Kornev, Tchesunov & Rybnikov, 2004 Boreotantulus Huys & Boxshall, 1988 Campyloxiphos Huys, 1991 Coralliotantulus Huys, 1991 Cumoniscus Bonnier, 1903 Deoterthron Bradford & Hewitt, 1980 Dicrotrichura Huys, 1989 Itoitantulus Huys, Ohtsuka Boxshall & Itô, 1992 Tantulacus Huys, Andersen & Kristensen, 1992 Onceroxenidae Huys, 1991: Onceroxenus Boxshall & Lincoln, 1987
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