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 enemys 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.
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.