This species of dolphin was only given its latin name 'delphinus
capensis' in 1994, when the short beaked dolphins were split
up from them. The long beaked common dolphin has less contrast
between the dark, white and yellow parts of its body.
Differences include a slightly longer body, males 2m - 2.6m,
females 1.9m - 2.3m and at birth 70cm+. They are also thinner
to, with a less rounded head. Also, they have a thicker, dark
line between the beak and the flipper. The most obvious difference
is that of the beak size. They mainly live in coastal regions,
and eat small fish and cephalopods.
The Common Dolphin (Delphinus delphis) is the name given to
two, or occasionally one species of dolphin, depending on
the taxonomical authority. Modern cetologists usually recognise
two species - the Short-beaked Common Dolphin which retains
the latin name Delpinus delphis and the Long-beaked Common
Dolphin - D. capensis. 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
Prior to the mid-1990s much of the literature lumped the entire
Delpinus genus into a single species, the Common Dolphin.
However 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 and short-beaked. This
analysis was essentially confirmed by a more in-depth genetic
study in the 1990s. This study also suggested that a third
species (D. tropicalis, 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 current standard taxonomic
works recognise this as just a regional variety.
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.
Some populations may be present all year round, others appear
to move in a migratory pattern. Preferred surface water temperature
is 10-28 degrees centrigrade. The total population is unknown
but numbers in the hundreds of thousands.
Common Dolphins 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 behaviour includes breaching,
tail-slapping, chin-slapping and porpoising.
Common Dolphins have been seen to mix with other cetaceans
such as other dolphins in the Yellowfish Tuna grounds of the
eastern Pacific and also schools of Pilot Whales. An intriguing
theory suggests that dolphins 'bow-riding' on very large whales
was the origin of bow-riding on boats.
The gestation period is about eleven months and the calving
period is between one and three years. Sexual maturation occurs
at five years and longevity is twenty to twenty-five years.
These figures are subject to large variation across different
Common Dolphins face 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 Dolphins have
not been hunted directly. Several thousand individuals have
been caught in industrial trawler nets throughout their range.
Common Dolphins were abudant in the western Mediterranean
Sea until the 1960s but occurences 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.
"Marine Mammals of the World. Systematics and Distribution",
by Dale W. Rice (1998). Published by the Society of Marine
Mammalogy as Special Publication No. 4
National Audobon Society Guide to Marine Mammals of the World
Encyclopedia of Marine Mammals ISBN 0125513402
Whales, Dolphins and Porpoises, Mark Carwardine, ISBN 0751327816