Spectacled Porpoise
Encyclopedia
The Spectacled Porpoise (Phocoena dioptrica) is a rarely seen member of the porpoise
family. The species is readily distinguished from other porpoises by a characteristic dark ring around the eyes, which gives the animals their name. This ring is commonly surrounded by a farther lighter ring. It does not wear spectacles.
. A skull later found in Tierra del Fuego
was initially thought to be another species, provisionally named Phocoena dioptrica but the individual was later shown to be a spectacled porpoise and this name remains a synonym. The Latin word dioptrica refers to the double eye rings characterizing the creature.
. They have a large rounded dorsal fin
, and no beak
. Like all porpoises, they have spade-shaped teeth (as opposed to conical in dolphins). Newborn members of this species are about 80 cm with males growing up to 2.2 meters and females somewhat smaller. The age at which they reach maturity, as well as the porpoise's longevity, is unknown. They can grow up to 60–84 kg (130-185 lbs) in weight as adults.
, the Falkland Islands
and South Georgia in the Atlantic, off Auckland
, Tasmania
and south Australia
in the South Pacific
and Heard Island and Kerguelen in the southern Indian Ocean
. Individuals have very rarely been seen in the open sea. The southernmost sighting was in the Drake Passage
at 58° S.
The total population is unknown. The IUCN lists it as a data deficient species in the Red List of Threatened Species.
). It is listed on Appendix II as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements.
Porpoise
Porpoises are small cetaceans of the family Phocoenidae; they are related to whales and dolphins. They are distinct from dolphins, although the word "porpoise" has been used to refer to any small dolphin, especially by sailors and fishermen...
family. The species is readily distinguished from other porpoises by a characteristic dark ring around the eyes, which gives the animals their name. This ring is commonly surrounded by a farther lighter ring. It does not wear spectacles.
Taxonomy
The Spectacled Porpoise was first described by Lahille in 1912 from a specimen found on a beach near Buenos AiresBuenos Aires
Buenos Aires is the capital and largest city of Argentina, and the second-largest metropolitan area in South America, after São Paulo. It is located on the western shore of the estuary of the Río de la Plata, on the southeastern coast of the South American continent...
. A skull later found in Tierra del Fuego
Tierra del Fuego
Tierra del Fuego is an archipelago off the southernmost tip of the South American mainland, across the Strait of Magellan. The archipelago consists of a main island Isla Grande de Tierra del Fuego divided between Chile and Argentina with an area of , and a group of smaller islands including Cape...
was initially thought to be another species, provisionally named Phocoena dioptrica but the individual was later shown to be a spectacled porpoise and this name remains a synonym. The Latin word dioptrica refers to the double eye rings characterizing the creature.
Physical description
The Spectacled Porpoise is a robust creature with a small head and no beak. Spectacled porpoises have distinctive black and white markings - black above and white underneath. They have black eyes with white rings or spectacles, and a white stripe on the upper surface of the tailTail
The tail is the section at the rear end of an animal's body; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammals, reptiles, and birds...
. They have a large rounded dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
, and no beak
Beak
The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...
. Like all porpoises, they have spade-shaped teeth (as opposed to conical in dolphins). Newborn members of this species are about 80 cm with males growing up to 2.2 meters and females somewhat smaller. The age at which they reach maturity, as well as the porpoise's longevity, is unknown. They can grow up to 60–84 kg (130-185 lbs) in weight as adults.
Diet
Porpoise feed on squid and fish, yet also on octopus, shrimp, mollusks, and other crustaceans.Behavior
Spectacled porpoises live in groups of 1-25. They are fast, active swimmers, and they normally avoid boats. Little else is known about their behavior as most of the information has been gleaned from stranded individuals.Distribution and population
The Spectacled Porpoise is believed to be circumpolar in cool sub-Antarctic and low Antarctic waters. Many skeletons have been found on Tierra del Fuego and this area is believed to be a site of relatively high concentration. This species has been seen off BrazilBrazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
, the Falkland Islands
Falkland Islands
The Falkland Islands are an archipelago in the South Atlantic Ocean, located about from the coast of mainland South America. The archipelago consists of East Falkland, West Falkland and 776 lesser islands. The capital, Stanley, is on East Falkland...
and South Georgia in the Atlantic, off Auckland
Auckland
The Auckland metropolitan area , in the North Island of New Zealand, is the largest and most populous urban area in the country with residents, percent of the country's population. Auckland also has the largest Polynesian population of any city in the world...
, Tasmania
Tasmania
Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...
and south Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
in the South Pacific
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
and Heard Island and Kerguelen in the southern Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
. Individuals have very rarely been seen in the open sea. The southernmost sighting was in the Drake Passage
Drake Passage
The Drake Passage or Mar de Hoces—Sea of Hoces—is the body of water between the southern tip of South America at Cape Horn, Chile and the South Shetland Islands of Antarctica...
at 58° S.
The total population is unknown. The IUCN lists it as a data deficient species in the Red List of Threatened Species.
Conservation
The Spectacled porpoise is listed on appendix II of the Convention on the Conservation of Migratory Species of Wild Animals (CMSBonn Convention
The Convention on the Conservation of Migratory Species of Wild Animals aims to conserve terrestrial, marine and avian migratory species throughout their range...
). It is listed on Appendix II as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements.