Definition
The sperm whale (*Physeter macrocephalus*) is the largest toothed predator on Earth. They are known for their enormous heads, which contain a large cavity filled with spermaceti, an oily substance. Sperm whales are deep-diving mammals that hunt squid and fish in the ocean's depths. They communicate using clicks and whistles. Think of them as the super-divers of the ocean, holding their breath for incredibly long periods. Unlike the agile dolphins, sperm whales are more like massive, slow-moving submarines.