Differentiate between complete and incomplete alimentary canal with an example

Complete and incomplete alimentary canals are two types of digestive systems found in different organisms.

1. Complete Alimentary Canal: A complete alimentary canal has two separate openings for food intake and waste expulsion, which are the mouth and the anus respectively. This type of digestive system is more advanced and allows for the simultaneous processing of ingesting, digesting, and egesting food. The food travels in one direction from mouth to anus. This system is found in higher organisms like humans, cows, dogs etc.

Example: In humans, the food enters through the mouth, travels down the esophagus into the stomach, then to the small intestine, large intestine, and finally exits the body through the anus.

2. Incomplete Alimentary Canal: An incomplete alimentary canal has only one opening that serves as both the entrance for food and the exit for waste. This means that the food enters and exits the body through the same opening. This system is less efficient as it cannot process food continuously. This type of system is found in lower organisms.

Example: In jellyfish, the food enters and exits through the same opening, the mouth, which leads to a gastrovascular cavity where digestion takes place.