Sea Cucumber

Kingdom: Animalia

Phylum: Echinodermata

Subphylum: Echinozoa

Class: Holothuroidea

Order: Aspidochirotida

Family: Holothuriidae

Genus: Holothuria

Species: Holothuria pardalis

Description

Sea cucumbers are part of a larger animal group called Echinodermata, which also contains starfish and sea urchins. Their body shape is extremely similar to that of a cucumber, but they have small tentacle-like tube feet that are used for locomotion and feeding. Depending on the species of sea cucumber, they normally vary in size from less than an inch to over 6 feet. All sea cucumbers are ocean dwellers, though some inhabit the shallows and others live in the deep ocean. They live on or near the ocean floor, sometimes partially buried beneath it. One way that sea cucumbers can confuse or harm predators is by ejecting their own internal organs from their anus in the direction of attack. The organs grow back, and it may save them from being eaten!

Anatomy

The sea cucumbers are long-bodied echinoderms with the mouth at or near one end and the anus at or near the other. In nearly all sea cucumbers the skeleton is reduced to microscopic ossicles embedded in the leathery skin. Sea cucumbers do not have any arms, but tube feet around the mouth have been modified to form a circle of 10 to 30 tentacles of varying lengths and shapes that function in gathering food particles from the ocean bottom. The gut ends in a chamber called the cloaca which opens into the anus. Two structures called respiratory trees, found in most sea cucumbers, also end in the cloaca. These are systems of highly branched tubes, one on either side of the body. The animal pumps water into the respiratory trees by contracting the cloaca, and oxygen diffuses through from the walls of the trees into the fluid of the body cavity. In a few sea cucumber species there is a large mass of tubules at the base of the respiratory tree that can be shot out of the anus if the animal feels threatened. The extruded tubules, which may engulf and harm an intruder, break off; they are then regenerated by the sea cucumber. In other species the respiratory trees, gonads, and part of the digestive tract are shot out through the anus; this is followed by regeneration of the lost organs. The sea cucumber has no true brain, but a ring of neural tissue surrounds the oral cavity and sends nerves to the tentacles and the pharynx. Even if the nerve ring is removed, it can still walk and move.

Diet

Sea cucumbers feed on tiny particles like algae, minute aquatic animals, or waste materials, which they gather with 8 to 30 tube feet that look like tentacles surrounding their mouths. The animals break down these particles into even smaller pieces, which become food for bacteria, and thus recycle them back into the ocean ecosystem. Sea cucumbers, particularly eggs and young larvae, are prey for fish and other marine animals. They are also considered to be a delicacy to humans, especially in Asia.

Reproduction

Sea cucumbers exhibit sexual and asexual reproduction. Unlike most terrestrial animals, sea cucumber eggs undergo external fertilization, meaning females release eggs into the water that are fertilized when they come into contact with sperm that males have released. In order for this form of reproduction to be successful, many males and females must be together at the same time.

Interesting Facts

Not only will the sea cucumber eject its internal organs when feeling threatened, cucumbers can expose skeletal, hook-like structures that would make them harder for predators to eat.

Another interesting fact pertaining to sea cucumbers is that they are commonly used in cancer treatments.

“They’re not only anti-viral, anti-bacterial but sea cucumbers have been used to treat gingivitis and gum disease, “ says Ty M. Bollinger, author of “Cancer: Step Outside the Box”.

They are used for those who are undergoing chemotherapy treatments because it’s very effective at mitigating the side effects of chemotherapy. Chemotherapy works to kill cancer cells, but in the meantime it will weaken the immune system greatly, the properties of the sea cucumber make your immune system stronger. Sea cucumbers are cytotoxic, meaning it kills cancer cells. They are also known for having high concentrations of chondroitin sulfate, which is normally used to treat joint pain and arthritis.

References

1. Attoub, Samir et al. “Frondoside A Suppressive Effects on Lung Cancer Survival, Tumor Growth, Angiogenesis, Invasion, and Metastasis.” PloS one (2013).

2. Battaglene, Stephen, and Evizel Seymour. "Survival and Growth of Cultured Juvenile Sea Cucumbers." Aquaculture 178.3-4 (1999): 293-323. Web.

3. Bollinger, T. M. (2007). Toxic Treatments. In Cancer-Step Outside the Box (pp. 75-88). Infinity 510.

4. Bordbar, Sara, and Farooq Anwar. "High-Value Components and Bioactives from Sea Cucumbers for Functional Foods—A Review." Marine Drugs 9.10 (2011): 1761-1805.

5. Graham, Ein. "Deposit- and Suspension-feeding Sea Cucumbers (Echinodermata) Ingest Plastic Fragments." Journal of Experimental Marine Biology and Ecology 368.1 (2009): 22-29.

6. Stonik, V., and V. Kalinin. "Toxins from Sea Cucumbers (holothuroids): Chemical Structures, Properties,Taxonomic Distribution, Biosynthesis and Evolution." Journal of Natural Toxins