Morfometría del tubo digestivo y alimentación del pepino de mar Athyonidium chilensis (Semper, 1868) (Echinodermata: Holothuroidea)

Holothurians are characterized for being deposit-feeders and can remove important amounts of biomass of organic matter of the marine bottom in zones where they are abundant. In Chile, Athyondium chilensis is the species of greater body size within its class and poorly studied in spite of its commercial importance. Thirty samples of A. chilensis were obtained from Caleta Chome (36°40′S, 73°10′ W) Chile, to make morphometric measures of their intestine and to analyze their relation with the body size and intestinal content. The diet was quantified by gravimetric method and frequency of occurrence, as also its relative abundance of four categories was quantified: microalgae, macroalgae, invertebrates and detritus, which were correlated with the body size of cucumbers. Thirty six prey items were identified mainly macroalgae and invertebrates. The relationships between the morphometric measures of the individuals and their intestine were positive as also these in relation to the weight of intestinal content. The relative abundance of macroalgae showed a negative tendency in relation to the size of sea cucumbers. The invertebrates, microalgae and the detritus showed a positive increase in relation to the body size of A. chilensis. This sea cucumber would be a key-species in the structure of sediments in intertidal and subtidal environments in the Chilean coast, with special emphasis to the places where they are very abundant.