(Lahille, 1912) - Spectacled porpoise
In spectacled porpoises, the body shape is typically porpoise-like, but the dorsal fin is large and rounded (in some adult males, it becomes extremely large). The flippers are small, with rounded tips. The beak is short or non-existent.
The two-tone colour pattern of spectacled porpoises is very distinctive. Above a line that runs down the side at the level of the eye (except that the line extends upward at the tail stock, just before the flukes), they are black. Below this line, they are white, with the exception of black lips and a dark gape-to-flipper stripe (the latter is apparently not present on all adults). There is a black patch, surrounded by a fine white line, around the eye. The flukes are black above and white below; the flippers are variably coloured, either all dark or greyish white with grey edges. Young animals have muted grey patterns.
Inside the mouth are 17 to 23 (upper) or 17 to 20 (lower) spade-shaped teeth in each row.
Can be confused with
The spectacled porpoise is not likely to be confused with other species, when seen well. But at a distance, there can be some confusion with Commerson's dolphin and Burmeister's porpoise, which both share portions of its range. These 3 species can best be distinguished by dorsal-fin shape and colour pattern differences.
Adult male spectacled porpoises reach lengths of at least 2.3 m and adult females are up to about 2.1 m. Newborns are probably about 1 m.
Known primarily from the southern coast of eastern South America, from Uruguay to Tierra del Fuego, this species is apparently also found around offshore islands in the Southern Hemisphere. There are records from the Falkland Islands, South Georgia, Kerguelen Islands, Heard Island, Macquarie Island, and the Auckland Islands. Although rarely seen at sea, this information suggests that the spectacled porpoise may be circumpolar in the subantarctic. Sightings have occurred in offshore waters, as well as in rivers and channels.
Biology and Behaviour
In the few known sightings, group sizes were small, apparently mostly singles and pairs. These animals are very inconspicuous when surfacing.
Births appear to occur in the southern spring to summer. Essentially, nothing else is known of this species' behaviour and biology.
In the past, spectacled porpoises were killed deliberately for food. In Argentina and Chile, spectacled porpoises are taken in gillnets, and they may be taken deliberately for crab bait off southern Chile. The effects of these catches on spectacled porpoise populations are not known.