Alimentary Systems of Different Animals

Topic Content:

Alimentary Canal in Lower Animals:

Planaria:

The planaria are free-living flatworms which are found on the bottom of freshwater lakes and streams and in certain moist land habitats.

They have a digestive system that consists of a pharynx, mouth, and small intestine. The small intestine has three branches, one anterior leading forward to the head and two posteriors leading towards the tail end. The gastrovascular cavity (anterior and posterior intestines) is lined with phagocytic cells , glandular storage cells and gland cells . These branches break off into numerous side branches.

The alimentary canal has only one opening to the environment. This opening serves as both mouth and anus.

Planaria are carnivorous in diet and feed on small organisms like crustaceans, larvae and small worms in the streams.

They capture their prey by entangling them in mucus glands. The entangled prey is then wrapped with the body of the planarian and the pharynx is then extended from the mouth which sucks in the small bits of the prey into the small intestine.

Both intracellularexisting, occurring, located or functioning within a cell. More and extracellularsituated or occurring outside a cell or the cells of the body. More digestionDigestion is the breakdown of large insoluble food compounds into small water-soluble components so that they can be absorbed into the blood plasma. In certain organisms, these smaller substances are absorbed... More occur in planaria.