The octopus belongs to a subclass of cephalopods. They are symmetric, with two eyes and four pairs of the arms (the reason they have got the name octopus, which means eight). Even though the octopus is a cephalopod, it is extremely different from its relatives such as oysters and snails. It’s more closely associated with the squid.
The octopus doesn’t have a shell; it has a hard beak, with its mouth at the centre. Since they don’t have a skeleton they could squeeze through narrow places and their favorite location is coral reefs.
If you meet an octopus under the water, move away as quickly as possible. They might not seem dangerous, but there is one type of octopus, the blue ringed octopus, which can be deadly.
For self defence, they hide, flee quickly, expel ink or they can even use colour changing camouflage. The octopus can change its color from red to gray, yellow, dark or greenish. At their back they have a type of muscular siphon. Water comes in the siphon, and the octopus takes the oxygen out of it. In that manner, the octopus can run away from a predator that has come too near.
The octopus moves by crawling and swimming. When they would like to travel slowly, they have a tendency to crawl with a pool. When they are helped by the jet propulsionthey move really fast, but even then they use walking and swimming.
When they crawl, they actually walk on their arms. Normally they use many legs simultaneously, on soft and solid surfaces. Recent research from 2005 revealed that some octopus can walk on two arms.
This way of moving (locomotion) helps octopus to flee from a possible predator. However, moving helps the octopus to capture its prey as well. The octopus eats mainly fish and goats, but if it’s hungry it catches everything.
For ingestion, the octopus uses its powerful jaws, which resembles the beak of a parrot. It can bite strongly and at the same time that it injects its poison. The poisonous liquid assists it in disabling its prey and its long arms, although they make the octopus look unusual with its sucking holes, it is with these it catches its prey and squeezes it securely.