Octopuses are boneless creatures. They don't have a vertebral column, that is, they are invertebrates. The beak which is in the shape of a parrot beak is the only hard structure in their body. Due to this reason, their bodies are extremely flexible and they can squeeze through incredibly small spaces.
Life span of octopuses depends upon their type (species). It may vary from 6 months to a couple of years. The larger ones live longer than those that are smaller in size.
Octopuses are bottom dwellers. However, as they hatch from the eggs, the young ones swim to the surface. After floating on the surface with the planktons for about a month, they swim back to the sea bed.
Octopuses may live in holes or crevices of rocks. Some of them make a protective area for themselves by piling up rocks. The small Atlantic pygmy octopus is known to inhabit an empty clamshell.
Octopuses vary in size depending upon the species. While those found in tropical waters are small, octopuses of the colder seas are larger in size. The giant Pacific octopus is the largest amongst all the members of the group and are known to grow as large as 23 feet. However, most octopuses are smaller in size. Usually they grow up to 10 feet and weigh around 55 ponds. Females are smaller than the males.
An interesting octopus fact is that these sea creatures have three hearts. Two hearts pump blood through the gills whereas the third one pumps blood through rest of the body.
Octopuses are stealth hunters. They change their colour to merge with the surroundings and wait for the prey to pass by. As soon as the prey is close within reach, the octopus grabs it with its long arms. It then secretes a nerve poison that stuns the prey. Octopus venom is poisonous and in some cases it can be fatal for human beings as well.
One of the interesting octopus facts for children is that these invertebrates can be kept as pets. However, keeping an octopus as a pet is difficult as these creatures have been reported to have escaped from supposedly secure tanks due to their intelligence and flexible bodies.
These eight legged creatures have highly developed sense of sight that helps them to hunt efficiently in the low light levels of the deep waters. They also have an excellent sense of touch. Octopuses have sensory receptors at the bottom of their suckers that enable them to "taste" whatever they touch. They are, however, deaf.
Male octopuses die within a few months of mating. However, males of larger species live longer. Female octopuses die soon after their eggs hatch.
The most remarkable octopus fact is that they have a number of defence mechanisms. They can change the colour of their body to merge with the surrounding that helps them to stay invisible from prey or predators. The first instinct of an octopus, when threatened, is to flee. Octopuses are known to eject a cloud of black ink when attacked by a predator. Sometimes they may also shed an arm to escape a predator. The lost arm regrow’s in some time.