Top 35 facts about Whales Whales are a type of marine mammal that belong to the order Cetacea, which also includes dolphins and porpoises. There are two main types of whales: baleen whales (also known as mysticetes) and toothed whales (also known as odontocetes). Baleen whales have a comb-like structure called baleen in their mouths that they use to filter small animals, such as krill and plankton, from the water. Toothed whales, on the other hand, hunt and eat larger prey, such as squid and fish. The largest animal on Earth is the blue whale, which can grow up to 100 feet (30 metres) long and weigh as much as 200 tons (181 metric tonnes). The blue whale's heart is the size of a small car and can weigh up to 1,000 pounds (450 kilograms). The humpback whale is known for its complex and beautiful songs, which can last for up to 30 minutes and be heard from miles away. Whales are highly s...