Life of Sea | Common Octopus (Octopus vulgaris) | Common Octopus is found worldwide in tropical and temperate waters. They are abundant in the Mediterranean Sea, off the coast of Japan, and in the Eastern Atlantic in coastal waters between 1-200 m. Similar to a squid, Common octopus is categorized as mollusk. It is a soft-bodied invertebrate with a shell. The octopus has no skeletal structure but does possess a skull, which protects its brain. It also has a sharp beak and a toothed tongue called a radula, which it uses to pry open and drill into the shells of prey, like crabs and clams. Once it breaks into the shells, the octopus may also inject a paralyzing poison into its prey.
Most scientists believe that Common octopus actually contains a number of related species. However, they have not yet decided how to split the species. Common octopus reaches between 30-91 cm in length. Like other octopus species, the soft-bodied common octopus has eight arms with numerous suckers, and there is no internal shell. It is able to change its color depending on its mood and situation, but individuals are usually greyish yellow or brownish green with extensive mottling. They are often very well camouflaged. The body is warty, and the thick arms bear two rows of suckers.
Like all cephalopods, Common octopus is an intelligent active predator. They have venom that used to poison their prey. It is often easy to identify what a common octopus has been feeding on, as they leave piles of debris known as middens around the entrance of the protective lair in which they live. These middens consist of debris from a range of species and often include mollusc shells and the carapaces of crabs and other crustaceans. All cephalopods are good swimmers, and are able to move rapidly by jet propulsion when threatened. Water is rapidly expelled through a funnel which causes the octopus to be propelled away rapidly. Cephalopods are also able to mask themselves as they escape with a cloud of ink released into the water.
Common octopus lays about 100,000-500,000 eggs about the size of a grain of rice during each breeding cycle that hatch and live in the plankton for 1.5-2 months. The juveniles that don't get eaten as part of the planktonic food web live up to 1.5 years. Common octopu is one of the most common octopus species commercially fished for food and for the aquarium trade. Between 10,000 and 20,000 metric tons are caught by commercial fisheries yearly using unbaited octopus pots. The pots draw the unsuspecting octopuses as a seemingly safe haven.