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|Sowerby's beaked whale (on Faroese stamp)|
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Mesoplodont whales are fourteen species of whale in the genus Mesoplodon, making it the largest genus in the cetacean order. Two species were described as recently as 1991 (pygmy beaked whale) and 2002 (Perrin's beaked whale), and marine biologists predict the discovery of more species in the future. They are the most poorly known group of large mammals. The word mesoplodon comes from the Greek meso- (middle) - hopla (arms) - odon (teeth), and may be translated as 'armed with a tooth in the centre of the jaw'.
- Mesoplodon bidens Sowerby, 1804 (Sowerby's beaked whale)
- Mesoplodon bowdoini Andrews, 1908 (Andrews' beaked whale)
- Mesoplodon carlhubbsi Moore, 1963 (Hubbs' beaked whale)
- Mesoplodon densirostris Blainville, 1817 (Blainville's beaked whale)
- Mesoplodon europaeus Gervais, 1855 (Gervais' beaked whale)
- Mesoplodon ginkgodens Nishiwaki and Kamiya, 1958 (Ginkgo-toothed beaked whale)
- Mesoplodon grayi von Haast, 1876 (Gray's beaked whale)
- Mesoplodon hectori Gray, 1871 (Hector's beaked whale)
- Mesoplodon hotaula P. E. P. Deraniyagala, 1963 (Deraniyagala‘s beaked whale)
- Mesoplodon layardii Gray, 1865 (Strap-toothed whale)
- Mesoplodon mirus True, 1913 (True's beaked whale)
- Mesoplodon perrini Dalebout, Mead, Baker, Baker & van Helden, 2002 (Perrin's beaked whale)
- Mesoplodon peruvianus Reyes, Mead, and Van Waerebeek, 1991 (Pygmy beaked whale)
- Mesoplodon stejnegeri True, 1885 (Stejneger's beaked whale)
- Mesoplodon traversii Gray, 1874 (Spade-toothed whale)
Longman's beaked whale (also known as the Indo-Pacific beaked whale) is also sometimes classed in the Mesoplodon genus. However, all recent authorities follow the lead of Joseph Curtis Moore, who put it in its own genus in the 1960s - Indopacetus.
Beaked whales are typically medium- to large-sized for toothed whales, three to six meters in length, but diminutive when compared with bottlenose whales and giant beaked whales. The females are the same size or larger than males in every species, but the males typically have a bolder coloration and a unique dentition. The lower jaw often forms a huge arch in some species, sometimes extending above the rostrum in a shape comparable to a playground slide. Every species has large (sometimes tusk-like) teeth of variable size, shape, and position. Gray's beaked whale, the exception, has numerous small and possibly functional teeth in the lower jaw. The males of most species are covered in scars from the teeth of other males. Both sexes often have bites from cookie-cutter sharks. The dorsal fin is rather small and located between two-thirds and three-quarters down the back of the animal. Information on longevity and lactation is non-existent, and information on gestation is nearly so.
Most species are very rarely observed, and little is known about their behavior. They are typically found in groups, possibly segregated between sexes. Some species are so uncommon, they have yet to be observed alive. On the surface, they are typically very slow swimmers and do not make obvious blows. They have never been observed raising their flukes above the water, either. They are all very deep divers, and typically feed entirely on squid.
The mesoplodonts are completely unknown as far as population estimates are concerned. They have been hunted occasionally by the Japanese, but never directly. They are also accidentally captured in drift nets. It is not known what effect this has on the population.
- Dalebout, M. L., Baker, C. S., Steel, D., Thompson, K., Robertson, K. M., Chivers, S. J., Perrin, W. F., Goonatilake, M., Anderson, R. C., Mead, J. G., Potter, C. W., Thompson, L., Jupiter, D. & Yamada, T. K. 2014. Mesoplodon hotaula: Resurrection of Mesoplodon hotaula Deraniyagala, 1963: A New Species of Beaked Whale in the tropical Indo-Pacific . Marine Mammal Science. DOI: dx.doi.org/10.1111/mms.12113.