Washed up on a beach in Southern Australia, scientists discovered the stranded body of a whale that baffled them. While it was obviously the carcass of a rare deep diving beaked whale, not often seen in the wild, the contents of its mouth threw the experts. Identified as a female, it had two small tusks normally only found in the male marine mammals. Was this a new species previously unidentified, or was this a strange oddity from the deep?
After taking it back to the South Australian Museum, the researchers were able to strip the skull of flesh, and revealed the two vestigial tusks poking out from the jaw. When the scientists removed them, however, they found two smaller teeth underneath, typical for a species known as Hector’s beaked whale (Mesoplodon hectori). Mystery seemingly solved. Yet this still doesn’t explain what a usually toothless female is doing with two prominent tusks.
The skull of the whale stripped of flesh, with the larger projecting tooth next to the normal one which was found underneath. South Australian Museum
There is a lot of mystery surrounding all species of beaked whales. This is due to their largely unexplored and unstudied habitat, their deep diving behavior, and their presumed low abundance. While 22 species of the whales are known to exist, only 4 have been studied in any detail, and even that this is generally because they either used to be – or still are – hunted commercially. The whales are unusual for their “beak” which makes them look more like dolphins, and are known for their deep diving habits. The record set for the deepest diving mammal is by the Cuvier’s beaked whale which has been clocked swimming at 2,992 meters (9,816 feet) down.
Close up detail showing the normal teeth found in female Hector's beaked whales (top) and the unusual larger teeth (bottom) normally reserved for the males. South Australian Museum
Bizarrely, most species only actually only have one pair of teeth, with one exception being Shepherd’s beaked whale, and these do not usually erupt through the females gums. It has been thought that they only project out in the males to aid in competing with each other for females. This is why the presence of the large teeth found in the female washed up in South Australia is puzzling, leading some to suggest that the stranded whale represents some sort of evolutionary throwback to when both sexes had prominent teeth.
With so few examples of the species, however, few conclusions can actually be drawn from this example. Are erupting teeth in females more common than previously thought, or is this simply a mutation seen in this one female? While most narwals have just one tusk, for example, sometimes the odd individual is found with two. Is this Hector’s beaked whale an equivalent example? The researchers have sent tissue samples away for genetic analysis to try and confirm their findings, and with so little known about the species, and group as a whole, any new information about them is invaluable.
