They are found on the sea floor worldwide , and occur in great numbers on the deep sea floor where they often make up the majority of the animal biomass .
Sea cucumbers are leathery echinoderms with elongated bodies which contain a single , branched gonad .
Sea cucumbers are found on the sea floor worldwide , and occur in great numbers on the deep sea floor where they often make up the majority of the animal biomass .
Sea cucumbers are leathery echinoderms with elongated bodies which contain a single , branched gonad .