Octopus

From ArticleWorld

A cephalopod of the order Octopoda, the octopus inhabits many regions of the ocean, especially coral reefs. There are 289 different octopus species. The term may also be used more exclusively to refer to only those creatures in the genus Octopus.

Physiology

Though commonly called tentacles, octopuses actually have eight arms, usually bearing suction cups. The majority of octopuses have no internal skeleton and no protective outer shell. A hard beak, similar to that of a parrot, is their only hard part. One reason octopuses have a relatively short life span, and some species live for as little as six months, is that reproduction itself is a cause of death. Larger species, such as the North Pacific Giant Octopus, may live for up to five years under suitable circumstances, however, males can only live for a few months after mating. Additionally, females die shortly after their eggs hatch, for they neglect to eat during the one month period spent taking care of their unhatched eggs.

Defense

Octopuses have three forms of self defense, ink sacs, camouflage, and autotomising (self-amputating) limbs. Most species of octopus can eject a thick, black, ink to aid in escaping predators. Color changing, and light reflecting, skin aids not only in camouflage, but also in communicating warnings to other octopuses. When under attack, some octopuses can autotomise their limbs, in a similar manner to lizards who will shed part of the tail structure and thus be able to flee. The Mimic Octopus, along with a few other species of octopus, has a unique fourth defense mechanism. They can combine their flexible bodies with their color changing ability to accurately mimic other, more dangerous animals like lionfish or eels.

Intelligence

Probably the most intelligent of the invertibrates, octopuses are shown to have both short and long-term memory. Although their short lifespans do limit the amount they can learn, in laboratory experiments, octopuses can be readily trained to distinguish between different shapes and patterns. Octopuses have been observed in what we may describe as play; repeatedly releasing toys into a circular current in their aquariums, and then catching them. Octopuses will often break out of their aquariums, and sometimes into others, in search of food. They have even been known to board fishing ships, and open holds, to eat crabs.