The Hourglass Dolphin is a sociable creature and will typically congregate into pods ranging in size from 1 to 100 individuals, with their average group size being around 7. Interestingly enough, these dolphins are not only sociable with their own species. They have been known to “hang out” with a variety of animal species.
Hourglass Dolphins feed primarily on fish, squid (Onychoteuthidae andEnoploteuthidae), and crustaceans. Squid beaks from these families were found in the stomach of one specimen, and the remains of Krefftichtys andersonii, a mesopelagic lantern fish were found in another. They are often seen feeding in large congregations near the surface, that attract albatross, petrels and other sea birds.
Like all toothed whales, the hourglass dolphin uses echolocation for orientation and prey location. A recent study showed that this species produces very high-pitched clicks, which allow it to detect prey at more than twice the distance of other dolphin species. It is thought that the hourglass dolphin is likely to communicate using sight and touch.
Native: Antarctica; Argentina; Australia; Chile; Falkland Islands (Malvinas); French Southern Territories (the) (Crozet Is., Kerguelen); New Zealand; South Africa (Marion-Prince Edward Is.); South Georgia and the South Sandwich Islands
These dolphins have been seen in the company of Arnoux's beaked whales, fin whales, sei whales, and minke whales. Very little is known about the natural history of this animal. Reproduction, mortality and other information about the hourglass dolphin is unknown.
This is a boisterous swimmer capable of speeds exceeding 12 knots. It rides bow-waves and stern-waves of fast boats and ships, swimming with long, low, leaps. From a distance, this undulating motion makes it look like a swimming penguin. It will also swim alongside slow vessels. When swimming fast, hourglass dolphins may travel very close to the surface, without actually leaving the water, creating a great deal of spray when rising to breathe.
The hourglass dolphin is a rare species of dolphin that can be found swimming in the Antarctic and Sub Antarctic oceans. This dolphin is so rare in fact that it is the only cetacean that has been classified as a species based solely on feedback from witnesses. Only a dozen or so hourglass dolphins have been examined so most of what is known about this species comes from the rare observations uncovered by those who have spotted it.
These dolphins have homodont dentition with 53-69 conical-shaped teeth. The dental formula is 26-34 teeth in the upper jaw with 27-35 teeth in the lower jaw.
Hourglass dolphins are small cetaceans with stocky bodies and characteristic black and white color patterns resembling an hourglass, hence their common name. These markings vary greatly among individuals. Based on the few records that exist for this species, they reach an average of 1.57 external m in length in females, 1.75 external m in males. Weight data is also scarce for this species, however the few weighed were between 74-94 external kg.
Hourglass dolphins were not given a classification until 1824 and were originally classified as Delphinus cruciger. The word cruciger is Latin for "cross-bearing" and is probably a reference to the hourglass pattern on the sides of these dolphins. This dolphin may also be classified as Lagenorhynchus wilsoni, for Edward Wilson, an Antarctic naturalist in the early 20th century. Other names for this species are skunk dolphin, Wilson's dolphin, and Southern White-sided dolphin.