tantulocarids

Tantulocarids are a group of small, parasitic crustaceans that belong to the infraclass Tantulocarida within the Maxillopoda. They are characterized by a unique parasitic life cycle and a distinctive body plan. Tantulocarids are endoparasites, meaning they live inside their host. Their hosts are typically other crustaceans, including copepods, amphipods, and cumaceans.

The adult tantulocarid, also known as the tantulus larva, is the parasitic stage. It has a sac-like body and a complex oral apparatus used to attach to and feed on the host. The tantulus larva possesses a distinctive frontal organ, a sensory structure whose exact function is still debated but is thought to be involved in host location or attachment.

Reproduction in tantulocarids is complex. The tantulus larva develops through several molts, eventually reaching a non-parasitic, free-swimming stage. This free-swimming form, the 'liberated larva', is believed to be responsible for dispersal and reproduction. It then develops into a free-swimming nauplius, which in turn metamorphoses into a new tantulus larva.

Tantulocarids are found in marine environments worldwide, from shallow coastal waters to the deep sea. Despite their small size, their parasitic nature can significantly impact host populations. They are of interest to marine biologists and parasitologists for their unusual life cycle and their role in marine food webs. There are currently over 80 described species of tantulocarids.