Blue whale
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Balaenoptera musculus

Names

Azores : "Finbeque" - POR : Baleia Azul - ITA : Balenottera Azzura - SPAIN : Ballena azul - GB : Blue whale - GER : Blauwall - NOORS : Blaahaval - JAP : Shiro nagasu kujira

Biology

The blue whale is the largest animal in the world. This species is divided in 2 sub-species. In the Azores you can find the sub-species Balaenoptera musculus musculus. The largest animal known to date measured 33 m and weighed 190 tons. However, adults' average size is 24 to 26 m in length. The females are slightly larger than the males. Newborns measure 7 m and they weigh 6 to 7 tons. Females bear a single calf every 2 to 3 years. Gestation lasts about 1 year and lactation takes at least 7 months. The young calf can drink 90 litres of milk per day. The body coloration is bluish gray with lighter spots spread all over the body. Compared with the other species of this family, the blue whale's head is flat in front of the blowholes. The dorsal fin is located in the last quarter of its back. The upper jaw has 270 to 400 pairs of black baleen plates that can reach 1 m in length and 55 cm in width. They have 55 to 90 ventral grooves in the throat, extending at least to the navel. They feed mainly on crustaceans such as krill, and they can eat up to 4 tons of these small crustaceans daily. The blue whale can live for up to 60 years. They can produce different types of sounds, such as ultra sounds with frequencies that range from 6 to 31 kHz, similar to the sounds emitted by the Odontoceti, and they also can moan in the range of 0.01 to 0.4 kHz.

Observation

Commercial hunting of this animal by other countries lead to the virtual extermination of the species. Nevertheless, its presence in Azorean waters was confirmed by sightings made by the team at Espaço Talassa between May and June 1997. In September 1999 we observed an individual measuring between 15 to 16m in length apparently feeding in the waters to the south of Lajes do Pico. This species can be easily confused with the fin whale or the Sei whale. However, its size can help to identify it with more accuracy. Other important characteristics of this species are longer diving times (up to 30 minutes), very impressive blow (it can reach as much as 9 to 12 m in height), and especially before diving, it elevates its tail out of the water. These animals can dive up to a depth of 150 m and cruises at a speed of 4 to 6 knots. This species could swim at speeds of 15 knots for several hours and, in some cases, even reach speeds of 20 knots.

Cetaceans in the Azores