The octopus is a soft-bodied, eight-limbed mollusc; around 300 species are recognised. Like other cephalopods, the octopus is bilaterally symmetric with two eyes and a beak, with its mouth at the center point of the eight limbs. The soft body can rapidly alter its shape, enabling octopuses to squeeze through small gaps. They trail their eight appendages behind them as they swim.
Maze and problem-solving experiments have shown evidence of a memory system that can store both short- and long-term memory.