Call me Ishmael…sighting of world’s rarest whale species

Image credit: Instagram/floramalein

Call me Ishmael. Some years ago – never mind how long precisely – having little or no money in my purse, and nothing particular to interest me on shore, I thought I would sail about a little and see the watery part of the world. – Herman Melville, Moby Dick

It is not, however, Captain Ahab’s white whale that we speak of, but something just as special: the spade-toothed beaked whale (Mesoplodon traversii). Until now this particular species of whale has only ever been identified from a handful of bone fragments discovered back in the nineteenth century.

The two dead specimens of the spade-toothed whale, a mother and a calf, were found in 2010 on Opape Beach in New Zealand.  Originally identified as the more common Gray’s beaked whales (a species that frequently gets stranded on New Zealand’s beaches), DNA analyses of their mitochondria revealed that they were the previously unseen spade-toothed whale. The discovery is described in a paper published on Monday in the journal, Current Biology.

Rochelle Constantine of the University of Auckland, one of the paper’s authors said:

‘Up until now, all we have known about the spade-toothed beaked whale was from three partial skulls collected from New Zealand and Chile over a 140-year period. It is remarkable that we know almost nothing about such a large mammal.’

Illustration depicting a generalized external morphology derived from photographs of the adult female spade-toothed beaked whale.

The species can be called the rarest species of whale as these are the only two specimens that have been sighted in 140 years.

Unlike the ferocious sperm-whale, Moby Dick, who seeks out and attacks sailors, the  beaked whale family has earned its reputation as the most ‘enigmatic’ of all whale species as they are thought to be exceptionally deep divers, hunting for small fish and squid, and only ever spending a short amount of time at the surface.

Made up of 21 species, it is very difficult to tell the difference between different members of the beak whale family (Family Ziphiidae) just by examining their features. The authors describe the importance of using new DNA techniques to help map the beak whale family tree saying:

Rapid advances in DNA technology are having a profound effect on our understanding of the natural world and have added value to museum and other reference collections.

Given that the South Pacific Ocean covers approximately 85 million km squared (around 14% of the Earth’s surface), it is perhaps not surprising that species like the spade-toothed whale only appear in the time-spans of centuries. Over 150 years later, it seems that Melville’s classic tale about the quest for a mythical whale stills holds some relevance to our understanding of whale species today.

Sources:

Thompson, K., Baker, C., van Helden, A., Patel, S., Millar, C., & Constantine, R. (2012). The world’s rarest whale. Current Biology, 22 (21) R905-R906. doi:10.1016/j.cub.2012.08.055

University of Auckland press release

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