What is the function of suckers in parasites?

Sucker in zoology refers to specialised attachment organ of an animal. It acts as an adhesion device in parasitic worms, cephalopods, and certain fishes and bats. It is a muscular structure for suction on the host or substrate. In parasitic worms such as annelids, flatworms and roundworms, suckers are the organs of attachment to the host tissues. In tapeworms and flukes, they are parasitic adaptation for attachment on the internal tissues of the host, such as intestines and blood vessels.[