Holothuriidae Family of Sea Cucumbers

Three Sea Cucumers of the Echinodermata Family can be found in this website:

Phylogeny: Sea Cucumbers of the Holothuriidae Family, like Starfish and Sea Urchins are in the phylum Echinodermata. They are in the subphylum Echinozoa, the class Holothuroidea, the subclass Actinopoda and the order Holothuriida. The Holothuriidae Family is one of two families in this order. The Holothuriidae Family contains five genera, eighteen subgenera,  and around two hundred sixteen species. The name Holothuriidae comes from the Latinized Greek words meaning “water polyp”.

Morphology: Not surprisingly, Holothuriid Sea Cucumbers are cucumber shaped. They lack arms, have a soft body wall, and branched tentacles around their mouth. utilized to capture food. The tentacles around their mouth are flattened, often leaf-like, and are utilized to capture food. They have a water vascular system, tube feet, and a complete digestive system, but they lack eyes, a head, nervous system, or excretory system. Their body wall is thick and leathery, with ossicles (tiny, calcified rods or tables under the skin). Their skin has fine to large papillae (projections). Their tube feet form a noticeable sole, and the feet may be spherical or elongate in shape. They vary in color and pattern, but most are black, brown, or greenish. Holothuriid Sea Cucumbers vary in size, from small, to over 60 cm (2 feet 0 inches) in length.

Habitat and Distribution: Holothuriid Sea Cucumbers are found in marine environments, on, under and within rocks, rubble, and sand. They live from the intertidal zone to depths that exceed 300 m (984 feet). They are found worldwide in temperate to tropical seas. At least thirty-one species from this family are found in Mexican waters.

Reproduction: Holothuriid Sea Cucumbers are gonochoric (either male or female for life). The reproduce sexually through broadcast spawning with external fertilization. The fertilized eggs hatch into planktonic larvae.

Ecosystem Roles:  Holothuriid Sea Cucumbers are active nocturnally. Some species are suspension feeders, filtering food from the surrounding water, and others are depositional feeders, gathering food from the surface of the substrate. Some filter sand through their digestive tracts, removing food from the sand as it passes through. They primarily eat detritus and diatoms. In turn they are preyed upon by crabs, crustaceans, fish, starfish, and sea turtles.  Sea cucumbers in this order may have one of two unique defense mechanisms. Some species can shoot sticky white threads (Cuvierian tubules) out of their anus, which may entangle or distract predators, allowing the sea cucumber to escape. Other species can eviscerate themselves by shooting their internal organs out of their anus, again, distracting a predator. These sea cucumbers have the ability to quickly regrow a new digestive tract.