A rare whale species observed on Antarctic expedition

The Arnoux’s beaked whale Berardius arnuxii. Credit: André Meijboom

The beaked whale species are a family of rarely seen whales. Despite there being 22 species of beaked whale (which we know about) they are rarely seen, and some have only been described in recent years.

Why are they seen so rarely? because they have a record breaking ability to hold their breath being able to hold it for over an hour (reasonably regularly) and have been recorded in dives lasting over 100 minutes. After sightings of this species, the researchers did a search and analysis of sightings between 1980 and 2000. Just 108 sightings were made, accounting for 1125 individuals.

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Southern right-whale dolphin

Southern right whale dolphin by Alcide Dessaines D' Orbigny

Southern right-whale dolphin

The southern right whale dolphin  is a small and slender species

 

 of cetacean, found in cool waters of the Southern Hemisphere. It is one of two species of right whale dolphin. This genus is characterized by the lack of a dorsal fin. The other species, the northern right whale dolphin, is found in deep oceans of the Northern Hemisphere and has a different pigmentation pattern than the southern right whale dolphin.

Southern right whale dolphins can be easily distinguished from other cetacean species within their range as they are the only dolphins without dorsal fins in the Southern Hemisphere. They have streamlined and graceful bodies, a single blowhole and a short and defined beak, possessing between 39 and 50 teeth per row.

A sharp dividing line separates the black dorsal part from the white ventral part of the body, running from the tail stock forward,  dipping down to the flipper insertion and sweeping back up, below the eyes, to cross the melon between the blowhole and snout crease. Younger individuals can be grey/brownish dorsally but develop adult coloration within the first year. The flippers of the southern right whale dolphins are small, recurved, predominantly white and located about one-quarter of the way back from the snout tip. Their flukes are small, have a white underside and dark grey upper side, with a notch in the middle and concave trailing edges.

There are no current global abundance and mortality estimates of the species although it is considered a fairly common and abundant species along its range, particularly in Chile. The very low sighting rate is most likely caused by a lack of sampling effort and due to the difficulties of sighting the animals in their offshore habitat.

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