Tail Flukes

As with all the cetaceans, all visible traces of hind limbs have disappeared - the hind limbs have evolved into a powerful tail. The tail of the dolphin (everything behind the dorsal fin) is used for propulsion: it is therefore very muscular. The tail is the primary source of power when it comes to propelling the dolphin forward.

Behind the anus, the body tapers into the tail stock (peduncle), which has flattened sides, and the horizontal flukes. The two flukes of the dolphin's tail are held rigid not by bones but by tendons and fibrous tissue. The flukes feel like dense rubber to touch.

Fluke profiles, viewed from above, vary considerably. Most are slightly convex at the back, but some are almost straight and others are conspicuously curved or even biconcave. Most species have a notch in the centre of the trailing edge.

The two flukes function as powerful paddles and are driven up and down by the well-muscled peduncle. The long powerful muscles of the peduncle, some of which originate far forward on the back, need to be firmly attached to the skeleton; the dolphin's vertebrate therefore have specially adapted long spines to which they are anchored.

The fluke also contains prominent blood vessels that help control body temperature. It acts as a heat exchanger during intense activity or when swimming in particularly warm water.

Bibliography

Harrison, Sir Richard, et. al. Whales, Dolphins and Porpoises. New York: Facts on File, Inc., 1994.

Mark Carwardine, The Book of Dolphins. Dragon's World Ltd, 1996

Tursi. "Tursi's Dolphin Page" Available http://www.neteng.bc.ca/~tursi/dolphins/index.htm, 4 September 1997, Accessed 4 April 1998