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Anatomy

Cetacean bodies are generally similar to those of fish, which can be attributed to their lifestyle and similar habitat conditions. Their body is well-adapted to their habitat, although they share essential characteristics with other higher mammals (Eutheria). Most notably, whales have a streamlined shape, and their forelimbs are flippers. Almost all have a dorsal fin on their backs, but this can take on many forms, depending on the species. A few species, such as the beluga whale, lack them. Both the flipper and the fin are for stabilization and steering in the water. The body is wrapped in a thick layer of fat, known as blubber. This provides thermal insulation and gives cetaceans their smooth, streamlined body shape. In larger species, it can reach a thickness up to 50 centimeters (1.6 feet). Hind legs are not present in cetaceans, nor are any other external body attachments such as a pinna.