External and Internal Features of Sea Cucumbers

Sea Cucumber, Trepang or Beche-De-Mer

Anatomical features of sea cucumbers View larger image

A circle of retractile tentacles surrounds the mouth. When feeding these spread out and look like a flower. The gut is a coiled tube containing mostly debris-laden sand particles. The excreta of sea cucumbers are easily recognisable on the sea bottom as coiled tubular threads of sand.

At the posterior end near the cloaca is the respiratory tree. This is a branched tubular structure which pumps seawater in and out through the cloaca for respiration. It is black or dark brown in colour.

Sticky, white thread-like structures called cuvierian tubules are sometimes found inside near the cloaca. In some species these have a defensive function, being thrown out when the animal is disturbed.

There are other important organs inside the body cavity for excretion and reproduction. The reproductive organs are prominent and visible only during the breeding season.