|Observations écologiques sur Holothuria tubulosa, H. poli et H. forskali (Echinodermata-Holothuroidea) et comportement alimentaire de H. tubulosa|
Massin, C.; Jangoux, M. (1976). Observations écologiques sur Holothuria tubulosa, H. poli et H. forskali (Echinodermata-Holothuroidea) et comportement alimentaire de H. tubulosa. Cah. Biol. Mar. 17(1): 45-59
In: Cahiers de Biologie Marine. Station Biologique de Roscoff: Paris. ISSN 0007-9723, more
Holothuria (Panningothuria) forskali Delle Chiaje, 1823 [WoRMS]; Holothuria (Holothuria) tubulosa Gmelin, 1791 [WoRMS]; Marine
3 Mediterranean holothurians H. tubulosa, H. poli and H. forskali have been observed in different places and the distribution of the animals according to ecological factors is being discussed. The alimentary behaviour of H. tubulosa has been studied by using coloured sand. This sp takes food continually and is a 'deposit feeder sediment-water interface selective'. The time estimation between the ingestion and the egestion of sand (Tp) is given by the following equations: Tp = 0.15 Lt-2.1 where Lt is the length of the digestive tract, Tp = 0.67 Lh - 3.3 where Lh is the animal length. Further the cinetic study of the ingestion of coloured sand by the holothurians has allowed the authors to establish the equations estimating the 'advancing state' of the meal for a given feeding time (Te): Lc = 3.5+7.5 Te where Lc is the digestive length filled after a time Te; Ic = 7.4+11 Te where Ic = (Lc/Lt)x100. The observations with coloured sand have also allowed the subdivision of the digestive tract into 3 parts characterized by their respective physiological functions. The 1st - part zone of sand accumulation-runs from mouth to sphincter marked by the inversion of the muscular layers of the digestive tract. The 2nd part-digestive segment surrounded by the rete mirabile; it is the part where the sand stays the longest. The last part-elimination zone-consists of almost all the 2nd descending digestive section. The observations and the results obtained, compared with the literature information point out that H. tubulosa is the Mediterranean homologue of the Indo-Pacific holothurian H. atra.