A mother and son pair of whales beached themselves on a New Zealand beach in 2010. Initially identified as Gray’s beaked whales, the pair turned out to be members of the never-before-seen species, the spade-toothed beaked whale (Mesoplodon traversii).
The spade-toothed beaked whale was previously known only from three partial skulls that had washed ashore on Pacific islands. In 1872, a lower jawbone with teeth from an adult male was found on the Chatham Islands. In the 1950s, a skull without a jawbone was found on White Island. Another skull without a jawbone was found in 1986 on Robinson Crusoe Island.
White Island and the Chatham Islands are near New Zealand on the western side of the South Pacific. Robinson Crusoe Island is near Chile, on the eastern side of the South Pacific.
The beached pair marks the first time the whales have been found complete and alive. Initially, they were identified as Gray’s beaked whales. Although both whales died before they could be rescued, DNA was extracted and added to New Zealand’s extensive whale DNA database. Comparisons of the DNA revealed that the pair were spade-toothed beaked whales.
Nobody is certain why spade-toothed beaked whales are so rarely seen. Perhaps they feed in the deeper waters or perhaps they stay far from land.
Source: Thompson, Baker, van Helden, Patel, Millar & Constantine. 2012. The world’s rarest whale. Current Biology https://dx.doi.org/10.1016/j.cub.2012.08.055