Attached to the floor of each suction disk are muscle fibers. When a squid touches its prey with these suction cups, the muscle fibers contract and cause suction. The two long tentacles are very mobile and not flattened until their end. The spatulate ends bear suction discs and are used for grasping prey and drawing it to their mouths. The octopi dwell on the ocean floor and they usually just wait for their favorite meal of shrimps, crabs fish and other molluscs to venture within their reach.
Octopods have eight tentacles, of equal length, covered with sessile suckers.
They do not possess a horny ring or hooks on their suckers, as do the squid. This is why they tend to end up as the only inhabitants of fish tanks they are accidentally or innocently deposited in. The nautilids possess approximately 94 tentacles that arise from lobes that are arranged in both the inner and outer circle around their head. These tentacles lack sucker or adhesive discs. They are instead annulated and can be drawn into a sheath.