Тантулокаридтер: Паразиттік шаянаттардың ерекше тобы

Subclass of crustaceans

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.

Eyes are completely absent. 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.

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 arthropod, with a total body length of only .

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. 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.