ABSTRACT
Many holothurians species present variations in their calcareous deposits, not only between different parts of their body (anterior-posterior; dorsal-ventral) but also during their life span. Deposits vary in size and form with advancing age or disappear. The first deposits disappearing are located at mid body. The spicule change is often abrupt: new spicules replace the oldest and it is not a gradual transformation.
Most of the holothurians presenting a strong variation between juvenile and adult calcareous deposits and/or a lost of calcareous deposits are Cucumariidae. Some Phyllophoridae, Ypsilothuridae, Caudinidae, Synaptidae and Stichopodidae present also similar variations. The holothurians concerned with modifications of deposits are mainly shallow-water species. However, their depth range extends often to the continental slope. Only one species is known from the abyssal zone.
The study of Cucumariidae coming from the Weddell Sea (Antarctica) and ranging from 4 to 70 mm long confirms that Heterocucumis steineni (Ludwig, 1898), Heterocucumis antarctica (Vaney, 1906) and Heterocucumis godfroyi (Vaney, 1914) represent different stages of a single species: H. steineni.
As calcareous deposits are the main character to differentiate holothurian species, the taxonomic status of many Antarctic dendrochirotes, established on juveniles or on deposit-free adults, needs to be revised on the basis of growth series.
