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.

Taxonomy

The Spectacled Porpoise was first described by Lahille in 1912 from a specimen found on a beach near Buenos Aires. 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.

Physical description

The Spectacled Porpoise is a robust creature with a small head and no beak. Males have a large dorsal fin. Individuals are dark grey to black on the dorsal fin with a very distinct line to a white to light grey ventral side. Newborn members of this species are about 80 cm with males growing up to 2.2 m and females somewhat smaller. The age at which they reach maturity, as well as a porpoise's longevity, is unknown. The Spectacled Porpoise is a fast swimmer.

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 Brazil, 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.

External links

• Spectacled Porpoise factsheet page from phocoena.org contains an image of the species