BLUE RINGED OCTOPUS

The Blue-ringed octopuses are small animals about 50 mm across from arm tip to arm tip. There are three distinct species that live in rocky shore environments from Australia to Japan. They are carnivores preying on small shrimp and crabs.

Probably the most remarkable aspect of the Blue-ringed octopuses is the potent venom. Delivered by biting, the venom is among the most deadly in the world and has resulted in a number of human deaths. No anti-venin is available at this time.

The venom is a mix of chemicals including tetrodotoxin which is present in the poisonous puffer fish and cone shells. Surprisingly, the toxin is not manufactured by the octopus but by bacteria living in its salivary glands. A bite from a Blue-ringed octopus can result in paralysis of the muscles and possibly a stop to breathing. The heart may also stop through lack of oxygen or paralysis.

First aid usually requires CPR and artificial respiration in hospital. Patients generally recover if respiration can be maintained for the first 24 hours. Because of the paralysis, some victims have been conscious of their situation but unable to call for help. Researchers have estimated that Blue-ringed octopuses carry enough venom to kill about 25 people.

The male Blue-ringed octopus is very enthusiastic where mating is concerned and will wrap his arms around the female to the point that he has to be forced to leave. Male octopuses produce small packets of sperm called spermatophores that are placed inside the female’s mantle (rounded body).

Blue-ringed octopus females lay only one clutch of about fifty eggs just once in their lives. Once the eggs are laid she carries them under her arms in front of her mouth. She does not eat for the six months it takes the eggs to hatch. Once the eggs hatch, the female dies. The young Blue-ringed octopuses will reach maturity and be able to mate by the next year.

My thanks to Zubi and the other photographers for these photos.


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The Incredible Octopus

One of the most interesting animals that I have worked with is the octopus. The name is from Greek meaning 8 feet (we call them arms). There are at least 300 species of octopuses and many more are sure to be found. They belong to a larger group of animals that include squid and cuttlefish and are known as cephalopods.

 

At the center of the 8 arms is the mouth with a parrot-like beak used for tearing food apart. In most octopuses the arms are lined along the underside with suction cups that provide a powerful grip.

The bulk of the body is like a rounded sack (mantle) that is quite muscular but has no skeleton. This flexibility allows it to change shape and squeeze through small openings in its rocky home. Inside the mantle are organs for respiration, circulation of blood, and reproduction. Octopuses swim by squeezing water out of the mantle as a form of jet propulsion.

Octopuses have three hearts. Two of these pump blood through the gills to get oxygen from the water and the third heart pumps the blood through the body. Unlike our iron-red blood, an octopus’s blood is blue from the copper that carries the oxygen.

 

Most octopuses don’t live very long breeding just once before they die. Small octopuses like the Blue-ringed live about a year and larger species like the North Pacific Giant may reach as much as 6-7 years old. In all species that have been studied, mating and the hormonal changes associated with it are the cause of death.

Depending on the species, females will lay from a few hundred to many thousands of eggs. After laying the eggs, the female will stop hunting and spend her time guarding her nest. Most eggs hatch within a month or so and the female dies soon after.

 

After hatching, the tiny octopuses are not fully developed and are called larvae. The larvae drift in the surface plankton feeding on small crabs and shrimp-like copepods. When they have developed enough they settle to the bottom and search for a suitable ‘home’. 

 

Many octopuses ‘decorate’ this home with pieces of shell and rock to make it more difficult for predators to see.

 

Octopuses are surprisingly intelligent; probably the most intelligent of all animals without backbones. Their large brain receives information from two very good eyes and millions of sensors all over their body. The complex nervous system allows the octopus to hide from its enemies using incredible camouflage. They can also surprise and confuse an enemy by releasing ink. The ink is a fluid made in their body and containing the pigment melanin (the same dark pigment in human skin).



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