Sea cucumbers belong to the family echinoderm of the class Holothuroidea, with an elongated body and leathery skin, which is found on the sea floor worldwide. It is so named because of its cucumber-like shape. Like all echinoderms, sea cucumbers have an endoskeleton just below the skin, but this can actually be absent in some species. These particular fellows are filter-feeders and have a crimson body with yellow tube-like feet. It is important to say that they release toxic gases when stressed or when they die.