Friday, November 9, 2012

Concealed cetacean

Something rather remarkable washed up on Opape Beach in New Zealand 2 years ago, although the enormity of the event was not at first known. A pair of beaked whales - mother at 5.3m long (somewhat bloody photo  here) and son at 3.5m - were found near death (and didn't survive). Because more than a dozen species are found in the area's waters, that in itself was not unusual. And since they have been tested for the last 20 years when they are found on the beaches, collection of samples by the Department of Conservation (DOC) was routine. But the results of DNA analysis revealed that these creatures had never been seen before. They were a species known to exist from partial skulls found in 1872, 1950 (image above), and 1986, but never observed in the flesh. Previously thought to be Gray’s beaked whales (photo here), their correct identification was confirmed by biologists Kirsten Thompson and Rochelle Constantine of the University of Auckland and their colleagues. "The vast expanses of the South Pacific Ocean have, until recently, concealed the identity of the world’s rarest whale, the spade-toothed beaked whale (Mesoplodon traversii). Based on the scarcity of records and the total absence of previous sightings, this species is the least known species of whale and one of the world’s rarest living mammals....We provide the first morphological description and images of this enigmatic species," reads the summary of their paper in Current Biology. All the species beaked whales are elusive, because they are likely deep divers and spend little time at the surface, and they have very similar external morphology. The distinguishing characteristics of the spade-toothed beaked whale include a dark gray or black rostrum, dark eye patch and flippers, white belly, and prominent melon (an organ behind the forehead that may play a role in echolocation). Luckily, the external appearance of the whales has been recorded photographically, since they had been buried and now exist only as skeletons. Who knows how many living specimens troll the ocean's depths?
For previous posts about whales,
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