Until fairly recently, Omura's whale (Balaenoptera omurai) was thought to be a smaller form of the Bryde's whale, as it is similar in appearance to that whale and the sei whale. In 2003, a detailed genetic analysis of museum specimens confirmed that Omura's whale was a separate species, and also indicated that there may be two separate species of Bryde's whale as well.
Since much of what is known of Omura's whale comes from specimens, there is not much known about their behavior and distribution.
Omura's whales are thought to reach lengths up to 40 feet and a maximum weight of about 22 tons. They have a dark upper side and white lower side, with asymmetrical coloration on their head - the lower jaw on their right side is white, but on the left side, it is gray. Omura's whales have one longitudinal ridge on top of their head, although they may have additional "accessory ridges" not as prominent as the main ridge. This separates them from Bryde's whales, who have 3 longitudinal ridges, although it makes them look similar to the sei whale, which has similar coloration and also has one longitudinal ridge on its head.
The distribution and migration patterns of Omura's whale are not well known. They are thought to live in subtropical waters in the western Pacific and eastern Indian Oceans. They have been recorded in the Philippines, Indonesia, Solomon Sea and
Little is known about reproduction in Omura's whale.
Omura's whales are listed as "data deficient" on the IUCN Red List. These whales have been hunted, but whaling records have not distinguished Omura's whales from Bryde's whales, so estimates of takes, and population size and distribution are difficult to determine.
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- Perrin, W. 2010. Balaenoptera omurai Wada, Oishi & Yamada, 2003. In: Perrin, W.F. World Cetacea Database. Accessed through: World Register of Marine Species, May 31, 2012.
- Reilly, S.B., Bannister, J.L., Best, P.B., Brown, M., Brownell Jr., R.L., Butterworth, D.S., Clapham, P.J., Cooke, J., Donovan, G.P., Urbán, J. & Zerbini, A.N. 2008. Balaenoptera omurai. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2.
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- Roach, J. 2003. New Whale Species Announced By Scientists. National Geographic. Accessed May 31, 2012.
- Save the Whales. Omura's Whale. Accessed May 31, 2012.
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- WDCS Species Guide. 2010. Omura's Whale: Balaenoptera omurai Accessed May 31, 2012.