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. The scientific name cruciger is Latin for "cross-carrier". This refers to the area of black coloration, which, viewed from above, vaguely resembles a Maltese cross or cross pattée.
Hourglass dolphins are distributed in a circumpolar pattern in the higher latitudes of the southern oceans (Goodall 1997; Goodall et al. 1997; Brownell and Donahue 1999). They range to the ice-edges in the south, but the northern limits are not well-known (they are found to at least 45°S, although some occasionally reach 33°S). The most southerly sightings are from near 68°S, in the South Pacific (Goodall 1997; Brownell and Donahue 1999). This is the only small delphinid species regularly found south of the Antarctic Convergence.
Habitat and Ecology
Normally seen far out to sea, L. cruciger has also been observed in fairly shallow water near the Antarctic Peninsula and off southern South America. It occurs within 160 km of the ice edge in some areas in southern part of the range (Jefferson et al. 1993). Most sightings of these dolphins are in an area around the Antarctic Convergence, between South America and Macquarie Island. The species seems to prefer surface water temperatures between 0.6° - 13°C (mean 4.8 °C; Goodall 1997) or even down to -0.3°C (Goodall 2002).
The stomach contents of the five specimens of hourglass dolphins that have been examined contained small fish (including myctophids), squids, and crustaceans. They often feed in aggregations of seabirds and in plankton swarms.
The species is widespread and abundant and no threats have been identified.
There are no known major threats to this species.