Right whale dolphin

Right whale dolphins
Northern species, Lissodelphis borealis
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Artiodactyla
Infraorder:	Cetacea
Family:	Delphinidae
Subfamily:	Lissodelphininae
Genus:	Lissodelphis Gloger, 1841
Type species
Delphinus peronii [1] Lacépède, 1804
Species
L. peronii Lacépède , 1804
Northern and southern right whale dolphin ranges

Right whale dolphins are

in 1804), little is known about them in terms of life history and behaviour.

Physical description

Both species have slender bodies, small, pointed flippers and a small fluke. Conspicuously, neither species has a dorsal fin; nor do right whales and this may explain the dolphins' name. The northern right whale dolphin is the only dolphin in the Pacific with this property. Similarly, the Southern is the only finless dolphin in the southern hemisphere. The two species can be readily distinguished (apart from the geographical separation in their ranges) by the extent of the whiteness on the body. Both have white bellies; however, the area of white coloration on the Southern species covers much more of the body — including the flanks, flippers, beak and forehead.

Northern males are about 220 cm (87 in) long at sexual maturity. Females are 200 cm (79 in). Both sexes become mature at about 10 years. New-born right whale dolphins are about half the length of their parents. The southern species is typically larger (up to 250 cm (98 in)) and heavier (up to 100 kg (220 lb) compared with the Northern's maximum of 80–90 kg (180–200 lb)). The dolphins live for about 40 years.

Distribution

The

. No global population estimates exist. There are an estimated 14,000 individuals close to the North American shoreline.

The southern right whale dolphin has a circumpolar distribution running from about 40° to 55°. They are sighted in the Tasman Sea in particular.

Behaviour

Both species are highly gregarious. They move in pods of several hundred individuals and sometimes congregate in groups of 3000.^[2] The groups may also contain dusky dolphins and pilot whales (in the south) and Pacific white-sided dolphins (in the north). These dolphins are some of the fastest swimmers (in excess of 40 km/h). They can by turns become very boisterous and breach and tail-slap or become very quiet and almost undetectable at sea. At high speed they can leap up to 7 metres across the ocean's surface in a graceful bouncing motion.

The species will generally avoid boats, but bow-riding has been recorded on occasion.

A single and rare stranding has been recorded for the northern species. On 9 June 2018, a 5.5-foot female was found deceased on Manzanita Beach on the coast of Oregon. There has been one recorded instance of 77 southern right whale dolphins stranding on Chatham Island.

Conservation

The southern species is under pressure from Peruvian whaling operations. The northern species has never been commercially targeted. However, tens of thousands of the northern species were killed in the 1980s due to their becoming caught in oceanic drift

in 1993. Conservation campaigners work vigorously to try to ensure these bans are retained.

Attempts to keep right whale dolphins in aquaria have all ended in failure and death. In all cases but one, they have died within three weeks.

References

Notes

Other sources

• National Audubon Society Guide to Marine Mammals of the World (2006),
  ISBN 0-375-41141-0
• ISBN 0-12-551340-2
• ISBN 0-7513-2781-6