The range is circumpolar from close to the Antarctic ice pack to about 45°S. The most northerly confirmed sightings were 36°S in the South Atlantic Ocean and 33°S near Valparaíso,
Chile, in the Pacific.
The hourglass dolphin (Lagenorhynchus cruciger is a small dolphin in the family Delphinidae that inhabits Antarcticand subantarctic waters.
The dolphin has rarely been seen. It was identified as a new species by Qouy and Galmard in 1824 from a drawing made in the South Pacific in 1820. It is the only cetacean to have been widely accepted as a species solely on witness accounts. By 1960, despite decades of whaling in the Southern Ocean, only three specimens had been recovered. As of 2010 only 6 complete and 14 partial specimens had been examined. Further information was obtained from 4 strandings and boats which searched for the dolphins in areas rarely visited by ships.
The hourglass dolphin is colored black and white and sometimes variations of dark grey. For this reason was colloquially known by whalers as a "sea cow". Each flank has a white patch at the front, above the beak, eye and flipper, and a second patch at the rear. These two patches are connected by a thin white strip, creating, loosely speaking, an hourglass shape and hence the common name of the dolphin.
A fully grown adult is about 1.8 meters (5.9 ft) length and weighs 90–120 kilograms (200–260 lb). Males are thought to be slightly smaller and lighter than females, although the small number of specimens does not permit a firm conclusion.
They share feeding grounds with other cetaceans. They are regularly seen with fin whales. Examinations of the stomach contents of the few specimens indicate they eat various types of squid and small fish.
Gestation lasts from 10 to 12 months, and results in the birth of a single calf.
Hourglass dolphins tend to move in groups of about 5 to 10. One International Whaling Commission study recorded a group of 60. Claimed groups of up to 100 have been found.