The southern right whale (Eubalaena australis) is a baleen whale, one of three species classified as right whales belonging to the genus Eubalaena. Like other right whales, the southern right whale is readily distinguished from others by the callosities on its head, a broad back without a dorsal fin, and a long arching mouth that begins above the eye. Its skin is very dark grey or black, occasionally with some white patches on the belly. The right whale’s callosities appear white due to large colonies of cyamids (whale lice).

Southern Right Whale

The right whales were first classified in the Balaena genus in 1758 by Carl Linnaeus, who at the time considered all of the right whales (including the bowhead) as a single species. Through the 1800s and 1900s, in fact, the family Balaenidae has been the subject of great taxonometric debate. Authorities have repeatedly recategorized the three populations of right whale plus the bowhead whale, as one, two, three or four species, either in a single genus or in two separate genera. In the early whaling days, they were all thought to be a single species, Balaena mysticetus.

The southern right whale spends summer in the far Southern Ocean feeding, probably close to Antarctica. Feeding can be occurred if there are any chances even in temperate waters such as along Buenos Aires. It migrates north in winter for breeding and can be seen by the coasts of Argentina, Australia, Brazil, Chile, Namibia, Mozambique, Peru, Tristan de Cunha, Uruguay, Madagascar, New Zealand and South Africa.

Females give birth to their first calf at about 8-10 years old. Gestation and weaning both last approximately 1 year. Females produce calves every 3 to 4 years. It is thought that right whales live at least 50 years, but there are few data on their longevity; closely related species may live over 100 years.

Southern right whales, so named because they were historically considered the “right” whale to catch, reach reproductive maturity at approximately ten years of age. The gestation period ordinarily lasts for one year, and lactation continues for four to six months. Calves, which are born weighing 1000-1500 kg and are five to six meters long, grow at a rate of 3 cm per day.

A Gull and a Southern Right Whale.

Southern right whales mate and calve between 20 and 30° S and mostly in protected bays during the months of June to November.

Southern right whales migrate to the southern latitudes of their range during the summer months where plankton populations are more abundant, and migrate north during winter and spring.

They do so at a rate of 2.7 to 4.2 kilometers/hour over a 24-hour period for cow and calf pairs. In addition, Eubalaena australis have been observed at near-shore swimming speeds of up to 15+ km/hr (for only short distances), but are generally slow swimmers.

Eubalaena australis produce short, low frequency moans and pulses. Also heard, often below and above the water’s surface, are the blows of the southern right whales. However, the most common sound produced is a belch-like utterance that averages 1.4 seconds long at a frequency of less than 500 Hz. These whales also produce simple moans in a narrow range of frequencies and complex moans that shift frequencies and overtones.

Using their long and numerous baleen plates, southern right whales feed on small plankton, including pelagic larval crustaceans and copepods. They are most often observed using one of two feeding techniques. The first, surface feeding, occurs when the whales selectively swim through densely-populated plankton slicks with their mouths wide open and baleen exposed. The other method occurs while submerged, presumably in highly dense populations of plankton.

Southern Right Whale diving.

Sources:

https://en.wikipedia.org/wiki/Southern_right_whale

http://www.nmfs.noaa.gov/pr/species/mammals/cetaceans/rightwhale_southern.htm

http://animaldiversity.org/accounts/Eubalaena_australis/

Anuncios