ABSTRACT
The associated organic fraction is clearly higher in the oesophagus sediment of Holothuria tubulosa than in the surrounding sediment. H. tubulosa appears to be able to select particles with the richest organic fraction. The organic matter of the gut content is progressively absorbed along the digestive tract. The efficiency of intestinal absorption is about 27 %. Faeces are always richer in organic content than the surrounding sediment.
