Résumé:
Sea cucumbers are invertebrates belonging to the phylum Echinodermata which is exclusively marine. Their systematics is reached by several approaches namely the morphological, endoskeletal and molecular approach. The objective of our work is to contribute to the systematics of six species of sea cucumber from the Algerian basin namely Holothuria (Platyperona) sanctori Delle Chiaje, 1823, Holothuria (Holothuria) tubulosa A Gmelin, 1791, Holothuria (Holothuria) algeriensis (tubulosa B) Gmelin, 1791, Holothuria (Roweothuria) poli Delle Chiaje, 1824, Holothuria (Roweothuria) arguinensis Koehler & Vaney 1906 and Parastichopus regalis (Cuvier, 1817) and that by the endoskeletal approach In this context, we have chosen the determination of the different types of sclerites of each species and in different parts of the body as well as their arrangement through the dermis of the dorsal and ventral surface. For this, we opted for the extraction of the ossicles using bleach and the use of xylene which has the property of making the tissues transparent to observe the arrangement of the sclerites in the dermis. The results obtained allow us to separate the different species by the approach discussed. The species Parastichopus regalis does not have button unlike the species of the genus Holothuria, which do have them and whose shape allow us to differentiate the species.
