Body Structure

Dolphins are mammals, just like us, with body hair to keep them warm and the ability to nurse their young with milk. Their hair is very limited, however, with only a few whiskers. Instead, they have a layer of fat under the skin called blubber, to maintain their warm body temperature. This layer can be a constant centimeter thick for tropical dolphins or it may change in thickness in areas with seasonal weather patterns.

As mammals, dolphins must breathe in oxygen just as we do, with lungs, by coming to the surface. They have their nasal openings on top of their heads, called a blowhole, which allows them to exhale and inhale quite rapidly to minimize the risk from exposing themselves in the open for very long.

A dolphin's body looks similar to a fish's in structure, due to the same need to be able to move quickly through the water. Dolphins have a dorsal fin, which provides stability while swimming and is composed of the same material as your ears. They also possess flippers, with the ones on their shoulders providing steering. Both the dorsal fin and flippers must be very rigid to work effectively. The "tail" at the rear of dolphins is referred to as a fluke and provides propulsion allow them to move forward at a high rate of speed. The fluke must be both flexible and stiff to allow for range of movement without sacrificing power.

Dolphins can have a length of 1.5 meters and a mass of 70 kilograms for the smallest ones, with the common bottlenose dolphin around 2 meters and 90 kilograms.

Dolphins continually dive under water but yet have the same lung capacity as most other mammals. They manage to stay under water for so long due to their ability to store more oxygen in their blood and muscles than humans or other mammals are able to. They also have a unique way to redirect blood flow from parts of their bodies that do not require a constant supply of oxygen, conserving it for their brain and vital organs.