Arnoux's beaked whale
| Arnoux's beaked whale Temporal range: Middle Miocene to present,
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|---|---|
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| Size compared to an average human | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Artiodactyla |
| Infraorder: | Cetacea |
| Family: | Ziphiidae |
| Genus: | Berardius |
| Species: | B. arnuxii
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| Binomial name | |
| Berardius arnuxii Duvernoy, 1851
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| Arnoux's beaked whale range | |
Arnoux's beaked whale (Berardius arnuxii), also called the southern four-toothed whale, southern beaked whale, New Zealand beaked whale, southern giant bottlenose whale and southern porpoise whale is one of the species of Berardius.[3] Arnoux's and Baird's beaked whales are so similar that researchers debated whether or not they are simply two populations of the same species, until genetic evidence and their wide geographical separation led them to be classified as separate. Little is known about their behavior due to infrequent encounters with live individuals.[4]
Etymology
[edit]Named Berardius arnuxii in 1851 for the French surgeon, M. Arnoux, who presented the skull to the Paris Museum of Natural History in 1846.[5]
Physical description
[edit]
Arnoux's and Baird's beaked whales, have very similar features and would be indistinguishable at sea if they did not exist in disjoint locations.[6] Both whales reach similar sizes, have bulbous melons, and long prominent beaks. Their lower jaw is longer than the upper, and once sexual maturity is reached the front teeth are visible even when the mouth is fully closed.[6][7] The Baird's and Arnoux's beaked whales are the only whales in the Ziphiidae family where both sexes have erupted teeth. The teeth in the Ziphiidae are presumed to be used by males for fighting and competition for females. Ziphiidae have the most prevalent and pronounced markings caused by teeth scarring among the cetaceans.[citation needed] Front-facing teeth may be covered in barnacles after many years.[7]
Baird's and Arnoux's beaked whales have similarly shaped small flippers with rounded tips, and small dorsal fins that sit far back on their bodies.[7] Adult males and females of both species pick up numerous white linear scars all over the body as they age, and these may be a rough indicator of age. These traits are similar in both sexes, as there is little sexual dimorphism in either species.[6][7] Among the observed differences in the sexes is their size: female Baird's and Arnoux giant beaked whales are slightly larger than the males.
Population and distribution
[edit]
Arnoux's beaked whales inhabit great tracts of the Southern Ocean. Large groups of animals, pods of up to 47 individuals, have been observed off Kemp Land, Antarctica.[8] Beachings in New Zealand and Argentina indicate the whale may be relatively common in the Southern Ocean between those countries and Antarctica; sporadic sightings have been recorded in polar waters, such as in McMurdo Sound.[9] It has also been spotted close to South Georgia and South Africa, indicating a likely circumpolar distribution. The northernmost stranding was at 34 degrees south, indicating the whales inhabit cool and temperate, as well as polar, waters. There is no stock report for the Arnoux's beaked whale to date by NOAA.
An April 2022 sighting in the Weddell Sea prompted a review of 108 prior sightings of 1125 individuals, dating to 1986-1998. This review corroborated their presumed range in the Southern Ocean, and found that Arnoux's beaked whales prefer the coasts of icy landmasses. In temperate regions above 60 degrees South, they can also be found near continents, even in fjords far inland.[10]
Conservation
[edit]Arnoux's beaked whale has rarely been exploited, and although no abundance estimates are available, the population is not believed to be endangered. Arnoux's beaked whale is covered by the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MOU).[11]
References
[edit]- ^ Brownell Jr., R.L. & Taylor, B.L. (2021) [amended version of 2020 assessment]. "Berardius arnuxii". IUCN Red List of Threatened Species. 2021: e.T2762A197190014. doi:10.2305/IUCN.UK.2021-1.RLTS.T2762A197190014.en. Retrieved 4 December 2023.
- ^ "Appendices | CITES". cites.org. Retrieved 2022-01-14.
- ^ Handbook of marine mammals. Vol. 4. Sam H. Ridgway, Richard J. Harrison. London: Academic Press. 1981–1999. ISBN 0-12-588501-6. OCLC 7819810.
{{cite book}}: CS1 maint: others (link) - ^ "Arnoux's Beaked Whale – A Complete Guide to Whales, Dolphins and Porpoises".
- ^ Australian Museum, Arnoux's Beaked Whale
- ^ a b c "Arnoux's beaked whale". Archived from the original on 4 February 2016. Retrieved 12 January 2016.
- ^ a b c d "Baird's beaked whale". WDC, Whale and Dolphin Conservation. Archived from the original on 17 July 2018. Retrieved 2018-06-07.
- ^ Rogers, Tracey L.; Brown, Sarah M. (1970). "Acoustic observations of Arnoux's beaked whale (Berardius arnuxii) off Kemp Land, Antarctica". Marine Mammal Science. 15: 192–198. doi:10.1111/j.1748-7692.1999.tb00789.x.
- ^ "Mystery Whales Put on Show at Scott Base | EveningReport.nz". Archived from the original on 11 March 2016. Retrieved 11 March 2016.
- ^ Feij, Bram; Kühn, Susanne; Meijboom, André; van Franeker, Jan A.; Bornemann, Horst; Kelly, Nat; Schaafsma, Fokje L. (2024-07-13). "Distribution of Arnoux's beaked whales ( Berardius arnuxii )". Marine Mammal Science. doi:10.1111/mms.13158. ISSN 0824-0469.
- ^ "CMS Pacific Cetaceans MOU for Cetaceans and their Habitats in the Pacific Islands Region". Archived from the original on 16 March 2016. Retrieved 10 April 2012.