Whales

Blainville’s Beaked Whale - Mesoplodon densirostris

The Blainville’s Beaked Whale, also called the dense-beaked whale, is possibly the strangest looking of all the whale species, with its flattened forehead and large spotted body. Males have a single large tooth at the midpoint of each side of the mandible. This tooth may be up to 20 cm in total length and is imbedded in a large hump of supporting bone that gives a high, arching contour to the lower jaw. Their jawbone is of a greater density than elephant ivory, hence their name, the dense-beaked whale. Females do not have so prominent a tooth and crested jaw. These large teeth erupt from its arched lower jaw, like horns, which are so encrusted with barnacles that the animal appears to have two dark coloured pom-poms on its head. This feature makes this animal relatively easy to identify at sea, although it is generally inconspicuous and difficult to find; it is known mainly from strandings.

The Blainville’s Beaked Whales measure 3 – 7 meters in length, with their colour tending to be grey brown on the dorsal side with a lighter grey to white on the ventral side. They are slender in shape, with short flippers which are set low on the body. Their rostrum is slender and pointed. They have an eye patch which is also dark, with females alone developing both white upper and lower jaws. Their bodies are often marked with scars and scratches, mostly likely due to competition among the males for females, using their two large teeth. Greyish scars also mottle their bodies left by parasites, such as squid ‘sucker marks’. Any additional teeth they may have are non-functional. Adults weigh 1 tonne with newborns weighing approximately 60 kilograms.

Blainville’s Beaked Whales are found in both temperature and tropical waters, more commonly off the coast of Hawaii. They are deep water whales, travelling either alone or in small groups of 1 – 12, remaining underwater for about 10 – 40 minutes at a time, surfacing to breathe for just a few minutes before returning to the water. It sometimes slaps its beak against the surface of the water, also occasionally rolling slightly before disappearing back under the water. When it surfaces, it does so slowly and with little splashing.

Sightings of these elusive creatures at sea are extremely rare due to their long dive times, deep habitat, and unobtrusive surfacing behavior. They are regularly spotted off the Waianae Coast of Oahu for prolonged periods annually, especially in slope areas of 500 – 1000 meters deep, with even deeper gullies nearby. They are uncommon residents of warm waters, occasionally seen in the western North Atlantic, Nova Scotia to Florida and the Gulf of Mexico. They are only known in Texas based on a single individual stranding in 1980.

Sounds recorded from a single young male stranded in Florida were described as ‘chirps’ and ‘whistles’. Research showed that some of these sounds were pulsed, indicating that possible echo-location in these whales may occur. Known to feed on squid, these whales are very rare and secretive