Sea Cucumber

Sea cucumbers, echinoderms from the class Holothuroidea, are very common in marine reef aquaria as they are prized for their unusual behaviour and appearance. Found on the sea floor worldwide, they have leathery skin and an elongated body containing a single, branched gonad, and they grow typically 10 to 30 centimetres (3.9 to 12 in) long. In the hobby, the sea cucumber consumes detritus that accumulates on the substrate (such as aragonite or sand).

Sea cucumbers can live without feeding for months, often up to half a year. If an aquarium system cannot support these creatures, the sea cucumber will shrink gradually as it digests its own body mass to survive, while starving. It would be wise to observe its proper feeding with signs of its feeding tentacles around its mouth to pick up and swallow sand from the bottom of the aquarium for planktons and decaying organic matter, and producing castings of excreted substrate.

Sea cucumbers can release highly toxic compounds, especially those known as “Sea Apples” which can be very lethal to the other tank inhabitants if they are injured. Be sure to to avoid possbilities of all powerheads and pumps to be accessible by them as they can squeeze themselves into spaces much smaller than their body. Remove any injured cucumbers immediately from the aquarium and perform a major water change, aided with activated carbon filtration to ensure the other inhabitants are saved.