Hyperoodon sp. (unidentified)
There have been several sightings at widespread locations in the tropical Pacific and Indian oceans of an unidentified whale that appears to belong to the genus Hyperoodon (possibly the southern bottlenose whale H. planifrons). These animals have steep bulbous foreheads and tube-like beaks. As in most other beaked whales, the dorsal fin is located behind the midpoint of the back, but it is larger than in other beaked whales. During these sightings, no teeth have been visible outside the closed mouth. Colour usually appears tan, but can range from umber-brown to bluish grey, generally with light areas on the sides and around the head. Some individuals have had scratches on the back. When seen, the blowhole was oriented with the concavity facing anteriorly; this is the opposite of the situation in Baird's beaked whale, the species with which it is most easily confused in the North Pacific.
Size estimates have been in the range of 4 to 9 m.
They are only rarely seen in the eastern tropical Pacific and there are a handful of sightings, as well as a single stranding possibly of this species, off Sri Lanka. Recently, there has been a report of what appears to be bottlenose whales in the Gulf of Mexico, as well.
Biology and Behaviour
It is thought that these animals may be southern bottlenose whales, which are normally widely distributed in the Southern Hemisphere, but so far no specimens have been collected to confirm this identification. It is also possible that these animals represent a third, as yet-unidentified, species of Hyperoodon. Herds of the unidentified whales have contained from 1 to 100 individuals, with many groups of 10 or greater (this is much larger than for Cuvier's beaked whale or the various Mesoplodon species).