Tantulocarida

Article By:

McLaughlin, Patsy A. Shannon Point Marine Center, Western Washington University, Anacortes, Washington.

Last reviewed:June 2020

DOI:https://doi.org/10.1036/1097-8542.677750

A subclass of the Crustacea. The Tantulocarida was initially proposed as a class of the Crustacea to accommodate two species formerly assigned to the Copepoda or Cirripedia, but now, with four additional genera that have been described, it is ranked as a subclass. Tantulocarids are minute ectoparasites, less than 0.01 in. (0.3 mm) in length, that infest deep-sea copepods, isopods, tanaids, and ostracods (see illustration). As a result of their parasitic mode of life, adult females have lost all resemblance to crustaceans; males are free-living but nonfeeding. Infection of the host occurs at the tantulus larval stage, which is believed to occur immediately after the larva is released. The head, or cephalon, of the tantulus larva is covered by a dorsal shield that may protrude anteriorly to form a rostrum. No cephalic appendages are present, although some of the specialized structures found in tantulocarids may possibly be derived from them. The mechanism of attachment, the mouth tube, is located on the ventral surface with a distal mouth opening, and is surrounded by an oral disk. The walls of the mouth tube consist, at least in part, of a pair of chitinous bars, each with a basal swelling. A second tubular structure, the longitudinal organ, projects into the mouth tube, reaching almost to the oral opening. A structure distinguished by its striated appearance, and referred to as the striated organ, lies above, in proximity to the dorsal surface of the head. A prominent, elongate cephalic stylet is located behind the oral region.

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