The Difference Between a Dorsal Fin & a Flipper

Location

• Location marks what may be the single biggest difference between dorsal fins and flippers on animals. The dorsal fin is located on the backs of most whales and dolphins, while flippers serve as the animal's "arms." That portion of a dolphin or whale's body that you see poking out of the water as it moves along the surface? That is the dorsal fin. The flippers are underneath the water, busy performing another task.

Function

• According to Sea World, the dorsal fin in whales and dolphins helps to stabilize the animal as it swims. Flippers allow the animals to change direction and aid them in stopping. Although flippers and the dorsal fin have different roles in movement, both help to keep the animals warm in cold water. Flippers and the dorsal fin contain arteries surrounded by veins. According to Sea World, heat from blood inside the arteries moves to the venous blood and is retained for warmth.

Anatomy

• According to Sea World, the dorsal fin on whales is made of tissue and contains no bone or cartilage. Because of this, a whale's dorsal fin bends easily. A whale's flippers, on the other hand, contain a skeletal system and tissue that resembles the human hand, albeit a shorter version. A penguin's flippers also have bones, but these are flattened and broad. Sharks are also slightly different, as they have two dorsal fins but no flippers, according to the Canadian Shark Research Laboratory. Dolphins differ slightly from whales in that their dorsal fin does contain cartilage, according to Robins Island. However, a dolphin's flippers also contain bones, cartilage and connective tissue, much like that of whales and penguins.

Necessity

• While all whales and dolphins need flippers to steer and retain body warmth, not all of these animals have dorsal fins. According to the Robins Island website, when the dorsal fin is absent it is usually replaced by the dorsal ridge. This ridge is made up of humps where the dorsal fin would be. Robins Island attributes this unique characteristic to an evolutionary change that allows dolphins and whales to swim along with ice flow without risking damage to the fin. Gray whales and Arctic whales are the most common example of animals with a dorsal ridge.