- Commerson's Dolphin
- Black Dolphin
- Heaviside's Dolphin
- Hector's Dolphin
Each of the four species in the genus Cephalorhynchus is found in the
Southern Hemisphere. Some of the world's least known dolphins, like the black
and Heaviside's dolphins, belong to this genus. Each species has its own range
with virtually no overlap, except a small area in the Strait of Magellan where
both the black and Commerson's dolphins may be found. All specimens are strongly
marked, with shades of black and white or black, white, and gray. One author
suggested the term "skunk dolphins" for individuals of this genus. Other than
that, there are no accepted common names for this genus. Sometimes the names
"short-nosed dolphins" and "southern dolphins" are used. All species of this
genus are small, with a maximum length of only 1.83 meters, most being smaller.
Most also have around 25-32 pairs of teeth in each jaw. Individuals are generally
shy, which contributes to their obscurity. The name Cephalorhynchus
roughly translates to "head-beak," with kephalos meaning "head" and rhynchus
meaning "beak" or "snout."
(Click for larger version)
A Couple of Commerson's Dolphins
From the NUS Dolphin Study Group
Etienne Douaze <email@example.com>
Permission obtained on 30 July 1998, Email message.
The Commerson's dolphin is in many ways a typical member of the genus
Celphalorhynchus, with a small size, brilliant coloration, and rounded
dorsal fin. It has a comparatively limited and isolated distribution, found
only along the eastern coast of the southern tip of South America, from
Peninsula Valdés, Argentina, to Tierra del Fuego, Chilean waters south of
51° S., the Falkland Islands, and the Kerguelen Islands in the southern
The middle portion of each of the sides of its small, stocky body is
white, while the head, flippers, flukes, posterior, dorsal fin, and dorsal
surface are black. There is a white patch on the ventral surface of the
anterior region, and a black patch on the otherwise white ventral surface just
caudal to the midline. The demarcation between the black and white portions
of the body are sharp. The small size, stocky build, and lack of a descernable
beak bear a resemblance to the porpoise, but the vivacious behaviour patterns
and the cone-shaped teeth are distinctly dolphin-like. The names "skunk
dolphin," "Black-and-White Dolphin," "Puffing Pig," and "Jacobite" have been
used to refer to this species.
Although it is sometimes stated that Commerson's dolphin is shy of boats,
modern accounts describe individuals frequently bow riding and pacing vessels
from alongside. They breach often and swim erratically, many times upside
down or on their side. Dives normally last 15-20 seconds after breathing
between 2 and 3 times. Individuals have been seen associating with Peale's
and Black dolphins and Burmeister's Porpoises.
(Click for larger version)
The black dolphin is the least known of the genus Cephalorhynchus,
with almost nothing known about the biology or natural history, no records of
specimens held in captivity, and almost no formal studies of the species. It
appears to be mostly typical of the genus, consuming similar prey, making
similar vocalizations, and having the same inherent wariness, which helps to
result in its obscurity.
The black dolphin is found only in Chilean waters between Valparaiso
(about 30° S.) and s. Isla Navarine, just north of Cape Horn, (55°. S.).
The most easterly sighting was in the Strat of Magellan, just east of First
Narrows (52° 30' S., 60°. 20' W.). It is possible that its range
extends south to Cape Horn (around 56° S.). There is very little overlap
between the range of the black dolphin and that of the Commerson's dolphin,
but they have been seen together in the Strait of Magellan, the Beagle
Channel, and Cape Horn. The records are from the edges of their respective
ranges. The distribution is more or less continuous within its range; there
are no significant gaps that isolate different groups.
The black dolphin in many ways resembles the Heaviside's dolphin, with a small adult size of around
1.4 meters, a low, rounded dorsal fin, and dark coloration. It has a white
throat and belly, a white spot behind the flipper, and a dark line on the
sides running from the cranial to the caudal end. When in the water, it is
described as tan, brown, lead-colored, or gray. Out of the water, it is found
to be nearly black on most parts and pure white on other parts. After death,
the color darkens quickly, especially if the specimen is left in the sun.
Its resemblance to various species of the family Phocoena probably
represents parallel development as the species occupy similar ecological
niches. Cetacean litterature includes many inaccurate descriptions of this
Very little is known about the black dolphin's behaviour. It is generally
not blatant or aggressive, and does not breach often. Individuals are often
seen with groups of feeding sea birds. The northern stock is far more gregarious
than the southern stock. While in the southern part of the range, individuals
are wary of boats and very difficult to approach, those in the northern areas
do occasionally approach boats and bow ride. In addition, groups in the north
are much larger, sometimes reaching as many as 4,000 individuals.
(Click for larger version)
Heaviside's dolphin, found in the waters of the Atlantic coast of southern
Africa, is not very well known. Its range is restricted, and it is not abundant
anywhere within it. It appears to be relatively continuously distributed along
approximately 1000 nautical miles on the western coast of southern Africa, from
Cape Point (34° 20' S.) in South Africa to at least Bosluisbaai
(17° 23' S.) in Namibia, and possibly as far north as southern Angola.
The short, robust body of Heavside's dolphin is typical of this genus,
although the head is slightly less conical than is normal. There is a groove
between the rostrum and the melon. Unlike many other members of the genus,
which have distinctly rounded dorsal fins, the dorsal fin of this species is
triangular. The color is blue-black on the dorsal side, with a gray "cape" over
the head and thorax. There are four areas on the ventral surface without
pigmentation. There is a transverse band in front of the pectoral fins, and
a trangular spot behind each of the pectoral fins. A longitudinal line is
found on the belly. It separtes into three equal forks just beneath the dorsal
fin. In many ways the coloration resembles that of the killer whale. Since
Heaviside's dolphin does not resemble the killer whale in size or habits, it
can only be assumed that this similarity in coloration is a way of confusing
their predators as to the identity of the species. At least one albino
individual has been reported.
Although Heaviside's dolphin is difficult to spot at sea due to its dark
dorsal side, it seems to be attracted to moving vessels. It has not been seen
feeding on the surface, but seems to like to feed in shallow inshore waters.
Either feeding normally takes place at night, or individuals with full stomachs
do not like to approach ships, since specimens captured in the afternoon did
not have much in their stomachs.
(Click for larger version)
Hector's dolphin is only found in the coastal waters of New Zealand, and in
general is not well known. It is, however, unlike other memebers of its
genus, fairly common and observed relatively often. Some have used the name
"little pied dolphin" to refer to this species. It may be found in the New
Zealand coastal waters between 35° 15' S and 46° 35' S, mostly between
41° and 46°. It is notably not found in Fiordland, on the southwestern
tip of South Island, probably because the water's depth is greater than 300
meters near the shore. In general it is rare on the southeastern coast.
As with other members of Cephalorhynchus, individuals of this species
are small, barely 1.5 meters. The species is easily recognized by the dark
colored and rounded dorsal fin, which resembles the adipose fin of Salmon. There
are black markins on the head and tail, while the body is silvery gray. The
forehead coloration is unique, with a dark, curved line forming a crescent
defining a light-colored area which is finely streaked with black sweeps down
toward the beak. The beak is poorly developed. The ventral coloration, unseen
except for beached individuals, is unique. Like other members of the genus,
there are 27-32 pairs of small, sharp teeth in each jaw. Its speed at sea is
known to be around 7-11 kilometers per hour, with bursts of 18 kilometers per
hour. The small size and
fast, low, and silent method of surfacing makes specimens difficult to see
except in calm conditions.
Groups of this species are around two to four individuals, with larger groups
reported. Unlike other members of the genus, this species is not terrbily shy
and will often approach boats. When one individual was captured, twelve others
surrounded the boat, lying motionless on the surface. In one case, an individual
stayed in the net while another individual, possibly the former's mate, was
trapped. It only left when the trapped animal was released. Hector's dolphin
tends to move much faster around the boat than the dusky dolphin, and does not
stay at the bow.
Baker, Mary L. Whales, Dolphins, and Porpoises of the World. New York: Doubleday & Company, Inc., 1987.
Carwardine, Mark. Eyewitness Handbooks: Whales, Dolphins, and Porpoises. New York: Dorling Kindersley Ltd., 1995.
Ellis, Richard. Dolphins and Porpoises. New York: Alfred & Knopf, Inc., 1982.
Klinowska, Margaret. Dolphins, Porpoises, and Whales of the World: The IUCN Red Data Book. Gland, Switzerland: World Conservation Union, 1991.