Sea cucumbers identification page


Sea cucumbers

Sea Cucumbers or Holothurians are part of the larger Echinoderm group, which includes sea urchins and starfish. They are probably one of the least attractive of the marine species, but they perform a vital role in the ecology of reef ecosystems, feeding on seafloor detritus and breaking it into smaller particles that bacteria are then able to process. As their common name suggests they have an elongated appearance, often with projections over a toughened skin. They are efficient vacuum cleaners with a mouth at the front and anus at the back. Most can be seen on the open seabed, although several species are filter feeders, living in burrows or attached to the seabed.

Blackspotted sea cucumber
Vacuum cleaning mouth parts of a blackspotted sea cucumber, spotted in Wakatobi.

This species group are not the preferred prey of fish, due to the presence of a toxic substance in their tissue, holothurin.  In addition to this, they have a clever and spectacular defensive habit of ejecting cuvierian tubules from their body cavity which create a mass of sticky string that entangles predators.

Donkey dung sea cucumber
A donkey dung sea cucumber, found in Sugar Beach, St Lucia.

Sea cucumber distribution

There are estimated to be 1,717 species worldwide, with the majority found in the Indo-pacific region, often at great depth. The greatest diversity in shallow waters may be found in the Caribbean and the Indo-Pacific. In particular, if you visit St. Lucia you will be able to see the attractively named Donkey Dung Sea Cucumber and the body waving Tiger Tail Sea Cucumber, along with three other species. In Indonesia, you can find the Sticky Snake, or Lion’s Paw Sea Cumber and if you visit Seychelles (for example in Port Launay), you will be able to see the cleverly named, Black, Green, and Brown Sea Cucumbers!

Sticky snake sea cucumber
A sticky snake sea cucumber photographed in Wakatobi, Indonesia.

Caribbean & Western Atlantic sea cucumbers

Indian & Pacific Oceans sea cucumbers

Eastern Pacific Ocean sea cucumbers

Mediterranean and Eastern Atlantic Ocean sea cucumbers

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