Octopoda

Octopoda is an order of soft-bodied, eight-limbed cephalopod molluscs, commonly known as octopuses, formally established in 1818 by the English biologist William Elford Leach within the class Cephalopoda, which also includes squids, cuttlefish, and nautiluses. The order comprises about 300 known species, found in marine habitats ranging from shallow tide pools to abyssal depths beyond 6,000 meters. Octopuses are distinguished by eight flexible, sucker-covered limbs arranged around a beaked mouth with bilateral symmetry, a soft body capable of radical deformation to fit through very small openings, and a highly complex nervous system, with more than 500 million neurons, that supports problem-solving and learning abilities often compared to those of mammals. They also employ sophisticated camouflage through color-changing chromatophores and body-texture changes, and move by jet propulsion, expelling water through a siphon.