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Phocoena dioptricaspectacled porpoise

By Jennifer Nixon

Geographic Range

Spectacled porpoises are rarely seen and are found only in the oceans of the southern hemisphere. Usually they are found near the southern east coast of South America (from Uruguay and Argentina to Cape Horn) and also near the Falkland Islands and South Georgia. Phocoena dioptrica have been seen near New Zealand, Macquarie Island and the Auckland Islands in the Pacific Ocean, and Heard Island and the Kerguelen Islands in the Indian Ocean. (Bannister, et al., September 1996; Brownell, November 21, 1975; Coffey, 1977; Minasian, et al., 1984; Tinker, 1988)

Habitat

Spectacled porpoises prefer cold ocean waters of the southern hemisphere. They normally live near offshore islands but are sometimes found in the open ocean. They seem to prefer the subantarctic area where there are cold currents like the Falkland Current. (Bannister, et al., September 1996; Nowak, 1999)

Physical Description

Size of this species can vary from about 1.25 meters (females) to 2.24 meters (males). The average weight of P. dioptrica varies from 55 to 80 kilograms; the largest individual found was 115 kilograms. The dorsal side is a blue-black color and the ventral side is pure white. There is a sharp line that divides the dorsal black color from the ventral white color. There is a gray line that goes from the corners of the mouth to the leading edge of the pectoral flippers, which are white. The lips are also black and the eyes are surrounded by black circles that look like glasses. The tail fluke is dark on the top side and white on the bottom. Shape also distinguishes this species. The dorsal fin is big and triangular and the pectoral fins are small and rounded when compared to other Phocoena species. The teeth in the upper jaw number between 18 and 23 and the teeth in the lower jaw number between 16 and 19 on each side. The teeth have spade-shaped crowns, which is a distinguishing characteristic of porpoises when compared to dolphins, which have cone-shaped crowns. There also are some skull features that distinguish P. dioptrica from P. phocoena: the top of the rostrum of P. dioptrica is flatter, and from the side, the premaxillary bones of P. dioptrica are less visible. (Bannister, et al., September 1996; Brownell, November 21, 1975; Coffey, 1977; Minasian, et al., 1984; Nowak, 1999; Tinker, 1988)

  • Sexual Dimorphism
  • male larger
  • Range mass
    115 (high) kg
    253.30 (high) lb
  • Average mass
    55-80 kg
    lb
  • Range length
    1.25 to 2.24 m
    4.10 to 7.35 ft
  • Average length
    2 males, 1.8 females m
    ft

Reproduction

No information is available on the mating systems of this species.

All mammals reproduce sexually via internal fertilization and all eutherian mammals give birth to live young. However, very little else is known about the reproductive behaviors of P. dioptrica. One near-term fetus was recorded in July 1912 and another was taken in August of the same year. The first fetus was a female and was 484 millimeters long. No information was recorded on the second fetus. The young are most likely born in early spring, but no information is recorded. (Brownell, November 21, 1975; Minasian, et al., 1984; Tinker, 1988)

A feature common to all eutherian mammals is that females nuture their young inside their bodies until birth, and afterwards provide them with milk. However, no specific information on parental investment is available for P. dioptrica.

  • Parental Investment
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female

Lifespan/Longevity

The lifespan of P. dioptrica is unknown.

Behavior

This species does not travel in large groups. They are probably solitary animals, but they have been seen in groups of two or three individuals. They are probably not migratory. (Bannister, et al., September 1996; Tinker, 1988)

Communication and Perception

Nothing has been recorded about the communication or perception of P. dioptrica, but they probably use echolocation as do other porpoises.

Food Habits

The food preferences of spectacled porpoises are not well known. They are most likely similar to other porpoises, which eat fish, squid, and crustaceans. (Bannister, et al., September 1996)

  • Animal Foods
  • fish
  • mollusks
  • aquatic crustaceans

Predation

Nothing is recorded about predation of P. dioptrica. It is possible that killer whales are their only natural predators. They also are hunted by humans. (Bannister, et al., September 1996; Brownell, November 21, 1975; Coffey, 1977)

Ecosystem Roles

Porpoises are predators of fish and aquatic invertebrates, and they sometimes provide a food source to killer whales. Nothing specific is known about the role of P. dioptrica in the ecosystem.

Economic Importance for Humans: Positive

Native people in South America hunt P. dioptrica, but not for commercial uses. (Coffey, 1977)

  • Positive Impacts
  • food

Economic Importance for Humans: Negative

Spectacled porpoises have no recorded adverse affects on humans. (Tinker, 1988)

Conservation Status

Not enough information is known about this species in order to list it as endangered.

Other Comments

Spectacled porpoises were previously known as Australophocaena dioptrica and Phocoena storni. Their Spanish common name is Marsopa de Anteojos. (Brownell, November 21, 1975; Tinker, 1988)

Contributors

Allison Poor (editor), University of Michigan-Ann Arbor.

Jennifer Nixon (author), University of Northern Iowa, Jim Demastes (editor), University of Northern Iowa.

Glossary

Atlantic Ocean

the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.

World Map

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

echolocation

The process by which an animal locates itself with respect to other animals and objects by emitting sound waves and sensing the pattern of the reflected sound waves.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

fertilization

union of egg and spermatozoan

food

A substance that provides both nutrients and energy to a living thing.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

pelagic

An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).

piscivore

an animal that mainly eats fish

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

solitary

lives alone

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Bannister, J., C. Kemper, R. Warneke. September 1996. "The Action Plan for Australian Cetaceans" (On-line). Accessed November 28, 2001 at http://www.deh.gov.au/coasts/species/cetaceans/actionplan/whaleap5a.html.

Brownell, R. November 21, 1975. <<Phocoena dioptrica>>. Mammalian Species Special Publication of the American Society of Mammalogists, No. 66: 1-3.

Coffey, D. 1977. Dolphins, Whales and Porpoises: An Encyclopedia of Sea Mammals. New York: Macmillan Publishing Co., Inc..

Minasian, S., K. Balcomb, L. Foster. 1984. The World's Whales: The Complete Illustrated Guide. Washington, D.C.: Smithsonian Books.

Nowak, R. 1999. Walker's Mammals of the World. Baltimore and London: Johns Hopkins University Press.

Tinker, S. 1988. Whales of the World. Honolulu, Hawaii: Bess Press Inc..

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