Strong muscles expand the mantle, drawing water into the mantle and over the gills. The muscles contract and send the water through a narrow muscular funnel. This funnel can be aimed forward or backward by the squid and gives it extraordinary manueverability. The adaptations required for this quick escape system are one of the reasons squid have been so valuable to science and is further explored in our section on neurobiology . The eyes are large and complex, giving the squid very sharp vision.
Squids have ten limbs, only two of which are appropriately called tentacles.
These are longer and can be extended out past the other eight arms to capture prey. Cuttlefish have a similar arrangment of eight arms and two tentalces ten while octopods only posess eight arms. The arms and tentacles of cephalopods possess rows of suckers that give the animal the ability to hold on to both prey and substrate. Octopus use the suckers on their arms to hold fast to rocks and plants. The suckers provide such a strong hold that it is impossible to remove a large octopus from a surface to which it has a solid hold.