Greenfish(Stichopus chloronotus)

Relationships: The Good, the Bad and the Evil

Interactions With Humans

Sea cucumbers have been harvested for Asian markets for over 1000 years.  The dried and processed body wall of the organism is more commonly known as bÍche-de-mer  or trťpang  in some areas. There are over 20 sought after species in this industry with Stichopus chloronotus being one of them. BÍche-de-mer is considered a delicacy in China and has also become a part of life and tradition for them. Along with being considered an aphrodisiac, it is believed to have medicinal purposes for aiding those with high blood pressure and muscular disorders. Its very low fat content makes it ideal for
people with high blood pressure and its high protein content is comparable to that of an egg. Sea cucumbers also contain copious  amounts of mucopolysaccharides, one of which being chondroitin sulfate, which is known for its ability to reduce arthritis pain and inhibit viruses such as herpes. Chondroitin can also be found in the cartilage of animals such as cows.

Although Stichopus chloronotus is considered to be a part of the bÍch-de-mer industry they are not highly sought after. One of the main reasons for this is because of their thin body walls. When the sea cucumber is processed the internal organs are removed, it is boiled in a salty water and then dried for preservation. When out of the water, the body wall of Stichopus chlorontus is extremely easy to dissolve and when it is boiled it is difficult to process the body wall without developing holes. This issue makes it very difficult to provide a high quality product.

Interactions With Animals

In order to protect themselves from predators, many holothurians, including Stichopus chloronotus, have developed toxins in their bodies.  This toxin is called holothurin which is a saponin and has been used for a long time by the South Pacific islanders as a means to catch tide pool fish. This toxin is often found in the body wall of the organism, more specifically, the Cuvierian tubules. Cuvierian tubules are long sticky organs attached to the respiratory trees in some species of holothurinas, and when threatened, it shoots its Cuvierian tubules from its anus, tangling the culprit in a sticky mess and possibly killing it with the saponins present in the tubules. Although Cuvierian tubules are found in numerous holoturians, they are not found in Stichopus chloronotus. Despite this lack of Cuvierian tublues, the saponins toxins are still found in its body wall and are highly toxic to  predatorial fish. Unfortunately, the saponins have little to no effect on organisms such as crustaceans. As a result, Stichopus chloronotus, and similar species, have developed an alternative means of escaping predators. As discussed in the reproduction and adaptations sections, Holothur
ians possess a tissue called “catch-connective tissue” that allows them to harden and soften their body. This tissue is also thought to be a defense mechanism against predators such as gastropods like Tonna Perdix, crabs and crustaceans.  When attacked Stichopus chloronotus will contract its body into a “U” shape which essentially causes the shedding of the skin that is being attacked.  The sea cucumber uses this as a distraction, allowing it to move away from the predator.  This response to danger is somewhat similar to what you find in species of lizards. The sea cucumber is also then able to regenerate lost tissue. This ability is not only useful after predatory attack but also in asexual reproduction. Other organisms that are capable of regeneration are salamanders. To learn more about these organisms, check out the tiger salamander or the
spotted salamander.

The Pearlfish

As discussed in the section on adaptation most holothurians utilize respiratory trees as a means of breathing. Surprisingly, these structures are also utilized by a species of fish called the Pearlfish. The tropical fish uses the respiratory trees of certain species of holothurian as its home and lives within the trunk of the trees. The fish will leave the host in order to find food at night and reenter it as the cloaca of the sea cucumber expands to breath. There can often be more than one found residing inside a sea cucumber and so far there seems to be no negative effects on the host making the relationship between the two a commensalistic  relationship.

Want to learn how to cook sea cucumber? Here are some recipes!

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