Dense-beaked whale
Blainville's beaked whale (Mesoplodon densirostris ), or the dense-beaked whale, is believed to be the widest ranging mesoplodont whale. The French zoologist Henri de Blainville first described the species in 1817 from a small piece of jaw — the heaviest bone he had ever come across — which resulted in the name densirostris (Latin for "dense beak"). Off the northeastern Bahamas, the animals are particularly well documented, and a photo identification project started sometime after 2002.
Blainville's beaked whales have long and narrow bodies. The melon of these whales is flat and hardly noticeable. They have a long beak, a pair of throat grooves which are located under the lower jaw, a small falcate dorsal fin, and a thick rostrum. Coloration is dark blue/gray on top and lighter gray on the bottom, and the head is usually brownish. Males have scars on their bodies and cookie cutter shark bites typical of the genus.
Blainville's beaked whales are found in all oceans. Strandings have occurred off Nova Scotia, Iceland, the British Isles, Japan, Rio Grande do Sul, South Africa, central Chile, Tasmania, and New Zealand. The most common observations take place off Hawaii, the Society Islands, and the Bahamas. These whales occur in tropical and temperate waters and prefer depths from 700 to 1000 meters.
Blainville's beaked whales are usually seen in groups of 3-7 individuals. They dive primarily to forage for food, diving more than 800 meters deep. It is thought that foraging at these depths helps to avoid predators, such as large sharks or Killer whales. Blainville's beaked whales forage during the day and night. Because these beaked whales almost exclusively vocalize while on their dives, it is believed that they are using sound to help their foraging. However, while on their dives they will produce whistles which are most commonly known for communication. This has left the true meaning of the Blainville's beaked whales vocalization a mystery.
Blainville's beaked whales are carnivorous. They feed primarily on squid, fish and other invertebrates.
Little is known about the mating system and reproductive behavior of Blainville's beaked whales. It is suggested that these beaked whales form harems. These harems consist of several females and a single dominant male. Females are known to give birth to a single calf. These whales reach reproductive maturity is 9 years of age.
Accidental hunting and chemical pollution are main threats to these whales. Climate change and noise are further threats to this species. The use of sonar from military vessels has caused mass strandings of Blainville’s beaked whales.
According to the IUCN Red List, the total population size of the Blainville's beaked whales is unknown. However, it is estimated 2,138 whales in Hawaiian waters. Currently, Blainville's beaked whales are classified as Data Deficient (DD) on the list of threatened species.
