Sea cucumbers and Star fish

Sea cucumbers
Holothurians

Usually, sea cucumbers are some of the safest reef animals to touch. However, they have a special organ called Cuvierian organ that contains toxic substances.

When in danger, these animals will expel their viscera together with the Cuvierian organ. In the water it becomes larger and splits into long white sticky threads that adhere to the enemy’s body. The venom of the sea cucumbers quickly weakens the muscles of the enemy and if the Cuvierian tubules come into contact with the eyes, the result may be permanent blindness.

The substance holothurin has been isolated from the Cuvierian organ. It is a strong poison- if 30 g of it are dissolved into 3 l of water, all fish swimming there will die within 30 minutes. Aborigines from the islands in the South Pacific knew that the viscera of the sea cucumbers contain a toxin. Since ancient times they used it to poison fish in closed lagoons. 

The holothurin blocks the transmission of nerve impulses, decreases the regeneration processes, kills microorganisms and prevents tumors. It is considered an effective treatment of skin fungi. Holothurin has been the source for production of a medicine that regulates cardiac activity, improves metabolism and has a general stimulating effect. Furthermore, some useful glycosides have been isolated from the sea cucumbers.

Star fish
This is a flat sea animal with five arms arranged in the shape of a star. The sharp spines are covered with thin venomous skin that can cause swelling, nausea and vomiting if it comes in contact with a wound. 

Starfish stick to underwater stones and ship corpuses so tightly that when they are removed they break off small metal parts from the ship. The strength of this adherence is just as equal as the strength of the very metal. The substance that the starfish release is a very strong glue and its hardener is the sea water. It is resistant to high temperature, acids, bases and solvents. It is possible that someday this glue will be of interest to dentists and ophthalmologists because it does not change its properties in an aquatic environment.