Common Name: Southern Dolphins
Class:
Mammalia
Order:
Cetacea
Family:
Delphinidae
Genus:
Cephalorhynchus
Species: Four
species:
Commerson's
dolphin C.
commersoni
Heaviside's dolphin C.
heavisidii
Hector's dolphin C.
hectori
Chilean dolphin C.
eutropia
|
Chilean dolphin,
Cephalorhynchus eutropia |
Genus: Cephalorhynchus
The dolphins of the
genus Cephalorhynchus belong to the Mammalian Order Cetacea,
in the suborder Odontoceti. All toothed whales belong to the
suborder Odontoceti, which is Latin for "toothed whales". These
dolphins belong to the oceanic dolphin family, Delphinidae. Other
members of this family include the killer whale, long-beaked common
dolphin, and pilot whale. The generic name, Cephalorhynchus,
is from the Greek kephale, which means "head", and
rhunkhos, which means "snout". This refers to the gradual slope
from the head to the snout, which lacks a defined melon and beak.
These dolphins are considerably smaller than most other oceanic
dolphin species and have a very recognizable blunt dorsal fin.
Chilean dolphin,
Cephalorhynchus eutropia
Southern dolphins are
generally darker shades of black or gray on their face, pectoral
fins, dorsal fin and flukes. Commerson's dolphin has the most
extreme contrast, with a white body. Other species are
predominantly gray. Adults of all species range from 3.5-5 feet in
length. These dolphins weigh between 60-190lbs. Males are
generally larger than females.
Groups of 1-5
individuals are commonly observed in shallow, murkier waters. The
Chilean dolphin occasionally enters river systems. Crustaceans,
squid and small fish are often taken in these shallow waters. Their
habitat and lifestyle is very similar to that of members of
Phocoenidae, which occupy coastal waters of the Northern
Hemisphere. Females give birth during the spring and summer
months. Gestation lasts about 12 months. Newborn calves are 1.5-2
feet in length, weighing about 10-17lbs. Sexual maturity is
attained at 5-9 years. Lifespan is estimated at 20 years.
Commerson's dolphin
Cephalorhynchus commersoni
The specific name,
commersoni, is named for Dr. Philibert Commerson (1727-1773), a
French naturalist aboard an expedition with French navigator Louis
Antoine de Bougainville during the 1760's. Commerson first
described these dolphins in 1767. Commerson's dolphin is native to
the coastal waters of southeastern South America, including
Argentina, Tierra del Fuego, Falkland Islands, Kerguelen Islands and
possibly even more southern islands including South Georgia and
South Shetland.
Commerson's
dolphin, Cephalorhynchus
commersoni
Chilean dolphin
Cephalorhynchus eutropia
The specific name,
eutropia, is derived from the Greek words eu, meaning “well
or good”, and tropis, meaning "keel". This may refer to the
shape of the skull, which has a keel-like ridge. Chilean dolphins
inhabit the coastal waters of southwestern South America, including
Chile and Tierra del Fuego.
Chilean dolphin,
Cephalorhynchus eutropia
Heaviside's dolphin
Cephalorhynchus heavisidii
The specific name,
heavisidii, is named for Captain Haviside, the first to describe
the dolphin in 1827. However, the captain's name was misspelled,
and the species is now commonly called "Heaviside's" dolphin.
Heaviside's dolphin is native to the coastal waters of southwestern
Africa.
Hector's dolphin
Cephalorhynchus hectori
The specific name,
hectori, is named for James Hector (1834-1907), a curator of the
Wellington Museum in New Zealand. Hector's dolphin is native to the
coastal waters of New Zealand.
Conservation
Coastal fishermen
occasionally capture individuals for bait or accidentally drown
dolphins in their fishing gear. All species are threatened by local
fishermen. Fortunately, the threats of fishermen have been
recognized and no members of this genus are in immediate threat of
extinction.