Lissodelphis borealis Skull Replica measures 17.7 inches. Lissodelphis borealis Skull is museum quality polyurethane cast. Made in USA. Cast of California Academy of Sciences Specimen. 2-part skull (separate cranium and jaw). Known as Northern Right Whale Dolphin.

The Lissodelphis borealis is a small, slender and finless species of cetacean found in cold temperate waters of the North Pacific Ocean.

Northern Right Whale Dolphin or Lissodelphis borealis have 37 to 54 thin and sharp teeth per row, which are not externally visible.

These cetaceans are predominantly black, white beneath, and some of the few without a dorsal fin or ridge. They are smaller members of the delphinid family, oceanic dolphins, and very slender.

Both species have slender bodies, small, pointed flippers and a small fluke. Conspicuously, neither species has a dorsal fin. The Northern Right Whale Dolphin is the only dolphin in the Pacific with this property.

The Lissodelphis borealis is widely distributed in the temperate North Pacific in a band running from Kamchatka and mainland Japan in the west to British Columbia down to the Baja California Peninsula in the east.

It is not known with certainty if they follow a migratory pattern. However, individuals have been observed close to the Californian shore following their main food source, squid, in winter and spring.

Both species are highly gregarious. They move in pods of several hundred individuals and sometimes congregate in groups of 3000. 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).  Lissodelphis borealis can 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 meters across the ocean’s surface in a graceful bouncing motion.

Unlike most delphinidae, Lissodelphis borealis vocalise without the use of whistles. Visual and audio surveys have confirmed that vocalisation primarily consists of clicks and burst pulses.

L. borealis have repetitive burst-pattern pulses that can be categorised and associated to different subgroups of L. borealis.

These vocalisations may be used in the communication between individuals, in a similar way to signature whistles in other delphinid species.

The evolutionary loss of whistling in Lissodelphis borealis may have resulted from a number of factors, such as predator avoidance, school size or school species composition.