Cephalopods - Feeding and Digestion in Molluscs

Cephalopods are carnivorous. Tentacles or arms are food capturing organs. The number of tentacles changes in different cephalopods. Sepia has ten arms, Octopus has eight and Nautilus has around 90 tentacles. Sepia, as other squids and cuttlefishes, has four pairs of short and heavy tentacles called arms and a pair of long structures termed as tentacles. The inner surface of the arms is provided along with suckers which are stalked, cup-shaped and adhesive in nature. The suckers are provided along with horny rings and hooks. In the mobile tentacles the suckers are present just only at the flattened ends. The arms aid in holding the prey tightly after it is captured. Suckers are available in the arms of Octopus as well but they are stalk less and devoid of horny rings and hooks. Cephalopods, besides radula possess a powerful pair of beak shaped jaws in the buccal cavity. The jaws are employed for tearing and biting the prey before the tongue like action of radula pulls the food down and aids in swallowing. Octopods inject the prey with poison or with no a bite with jaws and the prey are flooded with enzymes. After that the partially digested food passes into gut. When feeding on shelled gastropods, octopods drill a hole in the prey with radula and then inject poison into the animal by the hole. Whereas cuttlefish feed on surface inhabiting organisms such as shrimps and crabs, octopods feed on a range of prey including clams, snails and crustaceans. Nautilus is a scavenger-predator feeding specially on decapod crustaceans, specifically hermit crabs.