Most species are found in the deep sea. The suborder Incirrata contains the more familiar unfinned octopuses. Octopuses have evolved mechanisms to protect themselves from predators. Octopuses are able to jet water through their siphon by contracting their mantel to provide quick thrust. They can adapt to new situations and appear to be curious about their surroundings.
Octopuses can use their bodies as a nets to trap fish.
Having very little hard material in their bodies, usually only a beak and a radula, they can squeeze into amazingly small spaces. The lack of a hard defensive shell seems to make the octopus an easy meal. However, the above adaptations are often used together to effectively evade predators. An octopus could darken in color, expel a cloud or decoy of dark ink, immediately jet away while turning white, and then disappear under a rock, leaving the predator confused. Although octopuses possess beaks and cephalotoxins, they generally do not effect man.