Sea Cucumbers: The Vacuum Cleaners of The Deep

Sea cucumbers (Holothuroidea) are cylinder-shaped marine animals found in ocean floors worldwide. They have elongated, leathery and muscular bodies and spiny skin. There are about 1,250 known species, many of which are indeed shaped like soft-bodied cucumbers.

These nocturnal creatures can be as short as 0.75 in (2 cm) to over 6 ft (200m) long, and have an average lifespan of 5 to 10 years in their natural habitat.

Just like many bottom dwellers, the sea cuke can be in almost any color, many of them brightly and beautifully patterned. Though they look like worms, they are echinoderms, making them the sea star and sea urchin's relatives.

Sea cucumbers may or may not have tube feet. Some species have five double rows of tube feet running along their bodies. Each tube has a tiny suction cup on end, allowing the animal to feel and move.

Sea cucumbers are blind, though many of them are sensitive to light, that those that live in shallow waters tend to hide out during daylight hours, and comes out at night to feed.

These invertebrates reproduce by releasing their eggs and sperm into the water where they are fertilized and hatched.

Most sea cucumbers snack on tiny particles like algae, tiny aquatic animals, or decaying organic matter found in the sea bed. They also sift through the bottom sediments using their 8 to 30 tube feet that look like tentacles surrounding their mouth.

They may be brainless but they sure do know how to defend themselves. Some species contract their bodies to expel sticky cuvierian tubules (enlargements of the respiratory tree) to entangle potential predators. Their bodies have the ability to re-grow the tubules. Sometimes the act may be accompanied by the discharge of a toxic chemical called holothurin, which can kill any animal that can come in contact.

Many sea cucumber species are threatened to extinction as they are harvested for human consumption, and while toxins within the bodies of some species are supposed to deter predators, it has instead become a great pharmaceutical interest in Chinese markets.

The blood of the sea cucumber is yellow as ten percent of its blood cell pigment is vanadium.