The two curled, tusklike teeth of the male beaked whale evolved to attract females as well as to battle other males, according to new research.
Female beaked whales' apparent attraction to the tusks may have spurred the development of new species.
The unusual tusks—found on the outside of the male's mouth—have baffled scientists because they are not used for capturing prey, said study co-author Scott Baker, associate director of the Marine Mammal Institute at Oregon State University.
"Up until now, the purpose of the beaked whale tusks has been mysterious," he added.
Beaked whales and the narwhal are the only cetacean species with tusks, according to Baker. Cetaceans are marine mammals such as whales and dolphins. In the narwhal the single unicorn-like tusk is a modified upper tooth, whereas the paired tusks of the beaked whales are modified lower teeth.
After using DNA samples to reconstruct the evolutionary relationships of 13 of the 14 known beaked whale species, Baker and lead author Merel Dalebout of the University of New South Wales, Australia, said the tusks may help females identify male members of their own species to mate with.
The findings are published in the December issue of the journal Systematic Biology
