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The Hourglass dolphin according to MammalMAP
The Hourglass Dolphin – so named after the white hourglass pattern along its sides. This small, robust dolphin was first described in 1824 by Quoy and Gaimard and was also called ‘cross bearer’. For the Latin aficionados, it is called Lagenorhynchus cruciger.
Hourglass dolphins occupy the surface waters of the Antarctic and sub-Antarctic. This dolphin is so rare that it is the only cetacean to be described solely on feedback from witnesses. From the dozen of hourglass dolphins that have been formally examined, these dolphins grow up to 1.8 meters in length and weigh between 90 – 120 kgs.
Hourglass dolphins typically feed on fish, squid and crustaceans. The stomach contents of one specimen even had lantern fish. Hourglass dolphins are often seen feeding in large congregations near the surface. These congregations attract seabirds and researchers typically locate these dolphins by focusing on large groups of seabirds.
These dolphins are social animals. They are typically travelling in a small or large group. Hourglass dolphins are known to change course to bow ride along ships and large whales. There are no records of predation on this species but it is assumed that orcas are most likely to prey on them. It is thought that the counter-shading of hourglass dolphins protects them from predation – their lighter coloured belly blends in with the light when viewed from below and their dark back blend with the dark water when viewed from above.
According to the IUCN Red List, hourglass dolphins are a species of Least Concern. This species is widespread and abundant. No threats for this species have been identified for hourglass dolphins.