Common Dolphin

The Common Dolphin is the name given to two, or occasionally one species of dolphin. Prior to the mid-1990s, most taxonomists only recognized one species in this genus, the Common Dolphin. Modern cetologists usually recognize two species - the Short Beaked Common Dolphin, and the Long Beaked Common Dolphin.

Despite its name, the Common Dolphin is not the dolphin of popular imagination - that distinction belongs to the Bottlenose Dolphin, largely due to the television. Despite the historic practice of lumping the entire Delpinus genus into a single species, these widely distributed dolphins exhibit a wide variety of size, shape and colour. Indeed over the past few decades over 20 distinct species in the genus have been proposed.

Scientists in California in the 1960s concluded that there were two species - the long beaked Common Dolphin and short beaked Common Dolphin. This analysis was essentially confirmed by a more in-depth genetic study in the 1990s. This study also suggested that a third species, common name usually Arabian Common Dolphin, characterized by an extremely long and thin beak and found in the Red Sea and Indian Ocean, might be distinguished from the long beaked species.

The Common Dolphin is widely distributed in temperate, sub-tropical and tropical waters throughout the world in a band roughly spanning 40 degrees south to 50 degrees north. The variation in make-up described above from one population to the next suggested little interaction between distinct groups. The species typically prefer enclose bodies of water such as the Red and Mediterranean Seas. Deep off-shore waters and to a lesser extent over continental shelves are preferred to shallow waters. The total population is unknown but numbers in the hundreds of thousands.

The Common Dolphin travel in groups of around 10-50 in number and frequently gather into schools numbering 100 to 2000 individuals. These schools are generally very active - groups often surface, jump and splash together. Typical behavior includes breaching, tail-slapping, chin-slapping and porpoising.

The Common Dolphin faces a mixture of threats due to human influence. Populations have been hunted off the coast of Peru for use as food and shark bait. In most other areas the short beaked Common Dolphin has not been hunted directly. Several thousand individuals have been caught in industrial trawler nets throughout their range.

The Common Dolphin was abudant in the western Mediterranean Sea until the 1960s but occurrences there have tailed off rapidly there. The reasons are not well understood but are believed to be due to extensive human activity in the area.