Sperm whale

{{Taxobox | image2_caption = Size comparison against an average human | regnum = Animalia | phylum = Chordata | classis = Mammalia | ordo = Cetacea | subordo = Odontoceti | familia = Physeteridae | genus = Physeter | binomial = Physeter catodon | It has the biggest head of any animal. The head can be about 20 feet (6.1 m) long, and is about one-third of the whale's body. Its lower jaw is small and contains its huge, conical teeth (which fit into sockets in the upper jaw). They mostly hunt medium-sized squid. They also eat many kinds of fish such as skate. Sometimes they hunt giant squid that live on the ocean bottom at great depths. The largest bulls (males) will sometimes even eat colossal squid. This is crucial in hunting in the dark ocean depths.