What Divers Should Know About Sea Cucumber

Sea cucumbers play a vital role in marine ecosystems, diligently processing sediment as benthic scavengers. While some species inhabit extreme deep-sea environments, divers frequently encounter these fascinating echinoderms in shallower waters, often forming dense populations on rocky walls, sand, or silt bottoms. Recognized by their leathery skin and elongated, often cylindrical bodies, most species encountered by divers range from 10 to 30 cm (4 to 12 in) in length, though some can be much smaller or larger.

Observing their behavior reveals varied strategies for feeding and survival. Many sea cucumbers are detritivores, sifting through bottom sediments with specialized tentacles to gather plankton and decaying organic matter. Other species might position themselves in currents, extending arborescent tentacles to filter feed. Some can even burrow completely into sand or silt, extending only their feeding tentacles, ready to retract them swiftly if disturbed. This stationary, often buried, behavior makes them an interesting, albeit subtle, subject for underwater observation.