The octopus inhabits all oceans in depths that vary from 3 miles to more shallow waters along shorelines. They prefer to live in protected areas along the ocean floor such as coral reefs and rocky crevices.
There are about 300 species of octopus. The common octopus and briar octopus live along the Atlantic Coast, while the giant octopus and orange bigeye varieties reside along the Pacific Coast. In addition to living in protected areas, the octopus is equipped with strategies to increase its safety, including speed and the ability to expel ink into the water to confuse its aggressor. They also have autotomizing limbs that break off to allow the animal to escape.
Some octopuses are able to display color changes to blend into the background due to specialized skin cells. While some displays are used in communication with other octopuses, they are also used to appear like the surrounding rock, seaweed or other features. Deimatic displays, which are sudden colorful displays such as the appearance of giant eyes or brightly colored rings, frighten enemies away or give the octopus time to escape.
Although shy animals, octopus saliva contains poison that is normally used to catch prey but can also inflict a mortal wound on an enemy. The blue-ringed octopus is quite small but considered the most deadly. Its saliva contains venom capable of killing a human.