Lissodelphis borealis, Right Whale Dolphin [+]

Kingdom Animalia Phylum Chordata Class Mammalia Order Cetacea Family Delphinidae Genus Lissodelphis species: Lissodelphis borealis [+ITIS +WoRMS]

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Description & Behavior

The right whale dolphins include the northern right whale dolphin, Lissodelphis borealis (Peale, 1848), and the southern right whale dolphin, Lissodelphis peronii (Lacépède, 1804), and are small cetaceans with the most slender bodies of all small cetaceans. These dolphins do not have a dorsal fin or dorsal ridge which makes identifying them quite easy. They have small curved flippers, small tail flukes and short, well-defined beaks.

Lissodelphis borealis adults are usually black in color with a white band on the ventral side. The trailing edges of the flukes have light gray edging above and white below. They have 37-54 pairs of sharp, slender teeth in each jaw. Males are slightly larger than females measured up to 2.3 m (females) and 3.1 m (males). Maximum known weight is 115 kg.

Lissodelphis peronii adults are usually white on the ventral area which extends well up the sides; the sharp line demarcating black above and white below runs from the tail stock forward, dips down to the flipper insertion and then sweeps back up to cross the melon between the blowhole and snout crease. The flippers are generally white, but the trailing edge has a black band. The flukes are white below and dark grey, fading to white on the leading edge, above. They have 44-49 sharp, pointed teeth in each jaw. These dolphins reach lengths of at least 3 m and weights of 116 kg.

Like other dolphin species, right whale dolphins are a gregarious species found in schools of 200-2,000 that communicate using clicks and whistles and are often found in V-shaped configurations. They are fast and agile swimmers that reach speeds of up to 40 kph and have been observed breaching and displaying their flukes. They often school with other cetaceans such as the Pacific white-sided dolphin. Southern right whale dolphins are often found with other marine mammal species, especially dusky dolphins and pilot whales.

World Range & Habitat

The northern right whale dolphin, Lissodelphis borealis, is found in the northern Pacific Ocean between 35°N-51°N latitude. They live in deep open water where the temperatures vary between 8-24°C.

Southern right whale dolphins are found only in cool temperate to subantarctic waters of the Southern Hemisphere. The southern limit appears generally to be bounded by the Antarctic Convergence. The range extends furthest north along the west coast of continents, due to the cold counterclockwise currents of the Southern Hemisphere. The northernmost record is at 12°S in northern Peru. This is an open-ocean species, coming close to shore only in deep water coastal areas.

» GBIF occurrence data in Google Earth [Tips] | Ocean Biogeographic Information System (OBIS) (World Distribution) [about]

Feeding Behavior (Ecology)

Right whale dolphins feed on squid and fish, particularly lanternfish.

Life History

Almost nothing is known of either species' reproductive biology. There appears to be a calving peak in winter to early spring. Length at birth is unknown, but is thought to be approximately 1 m. Young animals have muted color patterns of dark gray and light gray.

Conservation Status/Additional Comments

The northern right whale dolphin, Lissodelphis borealis, is often caught by the North Pacific squid driftnet fisheries in Japan, Korea and Taiwan. Between 1985 and 1990 an estimated 15,000-20,000 dolphins were taken per year depleting populations by up to 73 percent. Although occasionally taken by whalers in the 1800s for food, southern right whale dolphins do not appear to be heavily hunted. They are known to be taken incidentally in driftnets along the coasts of Peru and Chile, and some are taken in the Peruvian small cetacean fishery.