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Kingdom
Animalia
Phylum
Chordata
Subphylum
Vertebrata
Class
Mammalia
Order
Cetacea
Suborder
Odontoceti
Family
Delphinidae
Species
Cephalorhynchus eutropia
Cephalorhynchus eutropia
black dolphin
2010/02/07 02:09:46.631 US/Eastern
By Bob Fan
Species:
Cephalorhynchus eutropia
Habitat
Depth
20 to 3 m
(65.6 to 9.84 ft)
On Chile's convoluted coastline, Chilean dolphins prefer to live near areas of particularly strong tidal flow above a steep dropping shelf. They are most commonly found in channels and open coasts and bays. They are also found in areas of tide rips at the mouth of fjords. They prefer cold, shallow water at depths of 3 to 15 m. They may also enter rivers and estuaries and can be seen as far as 5 kilometers upstream.
(
Brownell and Donovan, 1988
;
Grzimek, 2004
;
Reeves et al., 2002
;
Ridgway and Harrison, 1994
)
Physical Description
Mass
25 to 75 kg; avg. 50 kg
(55 to 165 lbs; avg. 110 lbs)
Length
1.60 m (average)
(5.25 ft)
Resembling fellow
Cephalorhynchus
species, Chilean dolphins are generally described as small and chunky with lengths of about 1.65 m for both males and females. These dolphins weigh approximately 57 kg, females may be slightly larger than males. Chilean dolphins have a stout, torpedo-like shape and can have a girth of up to two-thirds of their length. The head is conical in shape and lacks a beak and melon. The mouth line is fairly long and a groove on the sides of the face is present. The eyes are positioned just behind the mouth. The dorsal fin is low and triangular, with a long leading edge that is almost S-shaped. The flippers are rounded and medium sized. Some animals may also have serrations occurring along the edge of the flippers. Chilean dolphins are dark except for three areas of white on the throat, behind the flippers, and around the anal area. The rest of the body is a complex mix of dark tones. Areas of dark gray cover the flippers, flukes, back and dorsal fin whereas lighter gray tones cover the head and sides. The blowhole may be pale gray.
(
Brownell and Donovan, 1988
;
Jefferson, Webber, and Pitman, 2007
;
Macdonald, 1984
;
Reeves et al., 2002
;
Ridgway and Harrison, 1994
)
Chilean dolphins overlap in habitat with Commerson's dolphins (
Cephalorhynchus commersonii
). They can be distinguished by the lack of a conspicuous white area on the sides and back. Burmeister's porpoises (
Phocoena spinipinnis
) may also be confused, but they have more slender dorsal fins that are positioned farther back and a lower profile and more pointed peak.
(
Brownell and Donovan, 1988
;
Jefferson, Webber, and Pitman, 2007
;
Macdonald, 1984
;
Reeves et al., 2002
;
Ridgway and Harrison, 1994
)
Reproduction
Breeding interval
Females generally have one calf every two years.
Breeding season
Chilean dolphins breed in the winter.
Number of offspring
1 (average)
Age at sexual or reproductive maturity (female)
5 to 9 years
Age at sexual or reproductive maturity (male)
5 to 9 years
Little is known about the mating system and mating behavior of this species.
Chilean dolphins mate in the early winter and bear young in the spring. Females have one calf every two years. Sexual maturity is reached in 5 to 9 years. Other aspects of Chilean dolphin reproduction are not well understood.
(
Grzimek, 2004
)
Female Chilean dolphins invest heavily in young through gestation and lactation. Like other dolphins, young are likely to remain with their parents for long periods during which they learn complex social behaviors, navigation, and foraging.
Parental investment:
precocial
; pre-fertilization (provisioning, protecting: female); pre-hatching/birth (provisioning: female, protecting: female); pre-weaning/fledging (provisioning: female, protecting: female); pre-independence (protecting: female).
Behavior
Chilean dolphins are usually found in small groups of 2 to 3, although they can be found in groups of up to 20 individuals. Rarely, schools of 20 to 50 individuals have been sighted, particularly in the northern part of their range. In the southern portions of their range, they tend to avoid boats. All reports indicate that these dolphins are extremely shy and difficult to approach. Chilean dolphins have exhibited epimeletic behavior, in which healthy individuals provide assistance to injured individuals. A sub adult female, shot through the heart and aorta, was accompanied by several other animals during the time the animal was brought aboard. The animals then quickly fled after the female was brought out of the water. In contrast, an adult male that was shot was observed to be immediately abandoned by its group.
(
Brownell and Donovan, 1988
;
Macdonald, 1984
;
Reeves et al., 2002
;
Ridgway and Harrison, 1994
;
Wilson and Reeder, 1993
)
Home Range
Little is known about the home range and migration patterns of this species, although they are thought to be relatively sedentary.
Communication and Perception
Chilean dolphins produce "cries" consisting of rapid pulses at very low levels. Recording equipment at the time was not sufficient to capture the full extent of their sounds. They use echolocation to navigate their environment.
(
Brownell and Donovan, 1988
;
Ridgway and Harrison, 1994
)
Food Habits
Chilean dolphins commonly feed on small schooling fish, such as sardines (
Strangomera bentincki
), squid (
Loligo gahi
, for example), and crustaceans (such as
Munida subrugosa
). Chilean dolphins which have been observed near salmon hatcheries may eat young, newly released salmon.
(
Reeves et al., 2002
;
Ridgway and Harrison, 1994
)
Animal Foods:
fish; mollusks; aquatic crustaceans.
Ecosystem Roles
Commensal or parasitic species (or larger taxonomic groups) that use this species as a host
Economic Importance for Humans: Negative
There are no known adverse effects of Chilean dolphins on humans.
(
IUCN, 2008
)
Economic Importance for Humans: Positive
Chilean dolphins have been hunted in the past for food and as bait for lucrative crab farming. Fisherman use the meat from the dolphins as bait to catch king crabs although this practice is now illegal.
(
IUCN, 2008
;
Reeves et al., 2002
)
Ways that people benefit from these animals:
food
.
Conservation Status
IUCN Red List:
[link]
:
Data Deficient.
US Federal List:
[link]
:
No special status.
Chilean dolphins are listed as near threatened by the IUCN. Exact populations are difficult to measure but populations are considered in decline. Chilean dolphins have been hunted for food and as crab bait for generations. These dolphins are also accidentally caught in coastal gillnets. They also suffer from habitat encroachment by coastal salmon farming. More accurate information on Chilean dolphin populations and the threats they face is needed to formulate a conservation plan.
(
IUCN, 2008
;
Reeves et al., 2002
)
Other Comments
Extensive research on Chilean dolphins has yet to be conducted. They were previously called "black dolphins" because specimens that had died were darkened from exposure to air and sun. Animals seen at a distance in the water appeared black as well. This was largely unhelpful and ill-chosen as the species is shades of dark and light gray as opposed to black.
(
IUCN, 2008
;
Jefferson, Webber, and Pitman, 2007
;
Reeves et al., 2002
)
For More Information
Find
Cephalorhynchus eutropia
information at
Contributors
Bob Fan (author), University of Michigan. Phil Myers (editor, instructor), Museum of Zoology, University of Michigan.
Tanya Dewey (editor), Animal Diversity Web, University of Michigan Museum of Zoology.
References
Brownell, R., G. Donovan. 1988. Biology of the Genus Cephalorhynchus.
Reports of the International Whaling Commision
, Special Issue 9: 197-279.
Grzimek, B. 2004.
Grzimek's Animal Life Encyclopedia
. Detroit: Thomson-Gale.
Jefferson, T., M. Webber, R. Pitman. 2007.
Marine Mammals of the World: A Comprehensive Guide to Their Identification
. New York: Academic Press.
Macdonald, D. 1984.
The Encyclopedia of mammals
. New York: Oxford University Press.
Reeves, R., B. Stewart, P. Clapham, J. Powell. 2002.
Sea Mammals of the World
. London: A&C Black Publishers.
Ridgway, S., R. Harrison. 1994.
Handbook of Marine Mammals
. London: Academic Press.
Wilson, D., D. Reeder. 1993.
Mammal Species of the World; a taxonomic and geographic reference
. Washington: Smithsonian Institution Press..
2010/02/07 02:09:48.397 US/Eastern
To cite this page:
Fan, B. and P. Myers. 2009. "Cephalorhynchus eutropia" (On-line), Animal Diversity Web. Accessed February 09, 2010 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Cephalorhynchus_eutropia.html.
Disclaimer:
The Animal Diversity Web is an educational resource
written largely by and for college students
. ADW doesn't cover all species in the world, nor does it include all the latest scientific information about organisms we describe. Though we edit our accounts for accuracy, we cannot guarantee all information in those accounts. While ADW staff and contributors provide references to books and websites that we believe are reputable, we cannot necessarily endorse the contents of references beyond our control.
Other formats:
OWL
Sponsored in part by the Interagency Education Research Initiative,
the Homeland Foundation and the
University of Michigan
Museum of Zoology
.
This material is based upon work supported by the
National Science Foundation
under Grants DUE-0633095 and DRL-0628151.
The ADW Team gratefully acknowledges their support.
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