A new species, Holothuria (Mertensiothuria) arenacava (Echinodermata, Holothuroidea) from the littoral waters of Kenya is described. This species is characterized by its sand-burrowing behaviour, its small tentacles, the variously developed tables, corpuscules, buttons, plates and rods in the tube feet, and by the smooth, spiny and knobbed rods in the tentacles
