Diphyllobothrium latum

the broad tapeworm or fish tapeworm, a large species found in the intestines of mammals (including humans) that eat fish. It sometimes reaches a length of 9 meters, and its head has two grooves or suckers (bothria). It has two intermediate hosts, first a crustacean and then a fish. Called also Dibothriocephalus latus. See accompanying illustrations.

Life cycle of Diphyllobothrium latum.

Diphyllobothrium latum, cross-section of gravid proglottids (acetocarmine stain).