Complete alimentary canal is found in ascaris.
Ascaris are nematode roundworms that reside like parasites in a human being’s small intestine. These worms belong to the Ascarididae family, Secernentea class, and Oxyurida order. These worms, also known as Ascaris suum, are most commonly found in pigs. They are large roundworms that can achieve a length of 40 cm and have a mouth with three lips.