Sea cucumber (Holothuroidea) | Characteristics, Habitats & Amazing Facts

Name - Sea cucumber

Scientific Name : Holothuroidea

Type : Aquatic Animal 

Age : 5 to 10 years.

Diet : herbivores

Physical Characteristics:

Length : 2.5 cm To 1.8 m.

Weight : 400 grams to 2500 grams 

Top Speed : 50 mph 

Colour : red, black, blue, green or brown

Skin Type : soft which have some sort of skeleton below the surface of the body.

Lifespan : 5 to 10 years

Current Population : XXXXXX

Current Population Trend : decreasing

Native : Asia Pacific region


Main Prey : small food items, plankton floating in the water column, Algae, aquatic invertebrates, and waste particles

Habitat : all marine environments throughout the world

Predators : crabs, various fish and crustaceans, sea turtles and sea stars

Lifestyle : nocturnal 

Favourite Food : small food items on sea floor

Amazing Facts

  • The animals break down the particles into even smaller parts, which serve as food for bacteria, allowing them to be recycled back into the ocean environment. In terrestrial ecosystems, earthworms play a similar role.
  • Fish and other marine animals eat sea cucumbers, particularly their eggs and young larvae. Humans enjoy them as well, especially in Asia, and some species are farmed as delicacies.
  • Some sea cucumbers release sticky threads to entangle their foes when they are threatened. As a defensive mechanism, some will mutilate their own bodies. They contract their muscles aggressively and expel some of their internal organs from their anus. The missing body parts regenerate easily.
  • Sea cucumbers have the ability to reproduce both sexually and asexually. Sexual reproduction is more common, but it is not a very intimate process. Both eggs and sperm are released into the water, and fertilisation happens when they touch.
  • For this reproductive method to work, a sea cucumber population must have a large number of individuals. Indeed, huge herds of these ancient creatures graze on the microscopic bounty of coastal waters in many areas of the deep ocean.
  • The body is almost spherical or worm-like in shape, and it lacks the arms that many other echinoderms, such as starfish, have. The oral pole of other echinoderms (which, in most cases, is the underside) corresponds to the anterior end of the mammal, which contains the mouth, and the aboral pole, which contains the anus, corresponds to the aboral pole of other echinoderms (which, in most cases, is the underside).
  • Behind the mouth is a pharynx, which is surrounded by a ring of ten calcareous plates. This is the only significant part of the skeleton in most sea cucumbers, and it acts as a point of connection for muscles that can retract the tentacles into the body for protection, as well as the main body wall muscles.
  • While most animals have an oesophagus and stomach, some have a pharynx that opens directly into the intestine. The intestine is usually long and coiled, looping three times around the body before ending in a cloacal chamber or the anus.
  • The true brain of a sea cucumber is absent. The oral cavity is surrounded by a ring of neural tissue that sends nerves to the tentacles and pharynx. If the nerve ring is surgically removed, the animal can still work and walk around, showing that it does not play a central role in nervous control.
  • Sea cucumbers “breathe” by pulling water in through the anus and then expelling it, thanks to a pair of “respiratory trees” that branch in the cloaca just inside the anus and extract oxygen from water.
  • Some abyssal species in the Elasipodida order have evolved to be “benthopelagic,” meaning that their bodies are nearly the same density as the water surrounding them, allowing them to make long leaps (up to 1,000 metres) before slowly descending to the ocean floor. The majority of them have swimming appendages, such as an umbrella (like Enypniastes) or a long lobe on top of their bodies.
  • The larva develops into the doliolaria, which has a barrel-shaped body and three to five distinct cilia rings. The tentacles appear in the third larval stage of the sea cucumber, the pentacularia. Before the normal tube feet, the tentacles are normally the first adult features to appear.
  • The egg develops into a free-swimming larva in all other species after about three days of development. An auricularia is the first stage of larval development, and it is only about 1 mm (39 mils) long. This larva swims with the aid of a long band of cilia wrapped around its body, similar to the bipinnaria starfish larva.

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