Giant Beaked Whale

Els zífids de quatre dents (Berardius) són un gènere de dues espècies de zífid, el zífid de quatre dents meridional (Berardius arnuxii) i el zífid de quatre dents septentrional (Berardius bairdii). Les dues espècies són tan similars que alguns científics^[1] consideren la seva separació en dues espècies com a anomalia històrica. Són els zífids més grans i a vegades se'ls anomena zífids gegants.

Referències

Die Schwarzwale (Berardius) sind eine Gattung der Schnabelwale (Ziphiidae). Während ihr deutscher Name nicht aussagekräftig ist (schwarz gefärbt sind auch viele andere Wale), ist der englische Name „Giant Bottle-nosed Whales“ sehr viel treffender. Sie sind die größten aller Schnabelwale, mit Längen zwischen sieben und elf, ausnahmsweise sogar 13 m. Man unterscheidet drei Arten, die einander sehr ähnlich sind, den Baird-Wal (Berardius bairdii), den Südlichen Schwarzwal (B. arnuxii) und Berardius minimus, der erst 2019 erstmals beschrieben wurde.^[1]

Die Farbe variiert zwischen dunkelgrau, schwarzbraun und schwarz. Ein Schwarzwal trägt genau vier Zähne im Unterkiefer, während der Oberkiefer unbezahnt ist. Zwei dieser Zähne ragen selbst aus dem geschlossenen Maul heraus. Wie alle Schnabelwale tauchen auch die Schwarzwale extrem tief (2400 m sind belegt) und fressen hauptsächlich Tintenfische, aber auch Krebstiere und Fische.

Literatur

• Ronald M. Nowak: Walker's Mammals of the World. Johns Hopkins University Press, 1999 ISBN 0-8018-5789-9

Belege

1. ↑ Tadasu K. Yamada, Shino Kitamura, Syuiti Abe, Yuko Tajima, Ayaka Matsuda, James G. Mead and Takashi F. Matsuishi. 2019. Description of A New Species of Beaked Whale (Berardius) found in the North Pacific. Scientific Reports. 9: 12723. online

Weblinks

– Sammlung von Bildern, Videos und Audiodateien

The four-toothed whales or giant beaked whales are beaked whales in the genus Berardius. They include Arnoux's beaked whale (Berardius arnuxii) in cold Southern Hemispheric waters, and Baird's beaked whale (Berardius bairdii) in the cold temperate waters of the North Pacific. A third species, Sato's beaked whale (Berardius minimus), was distinguished from B. bairdii in the 2010s.^[2]

Arnoux's and Baird's beaked whales are so similar that researchers have debated whether or not they are simply two populations of the same species. However, genetic evidence and their wide geographical separation has led them to be classified as separate.^[3] Lifespan estimates, based on earwax plug samples, indicate male whales can live up to 85 years, while females can have a lifespan of 54 years.^[4][5] It is estimated that the length at birth is ~4 metres (13 ft). Growing up to ~10 metres (33 ft), these are the largest whales belonging to the family Ziphiidae.^[6] Sato's beaked whale is much smaller, with adult males having a length of ~7 metres (23 ft).^[7]

While Berardius arnuxii and Berardius bairdii are considered least concern by the IUCN.^[8][9] Berardius minimus is labeled as near threatened as of 2020.^[10]

This article currently largely treats four-toothed whales as monospecific, due to a lack of species-specific information.

Species overview

Berardius was once classified as containing only two species: Arnoux's beaked whale (Berardius arnuxii) in the Southern Hemisphere waters, and Baird's beaked whale (Berardius bairdii) in the North Pacific.^[11] Arnoux's beaked whale was described by Georges Louis Duvernoy in 1851. The genus name honors admiral Auguste Bérard (1796-1852), who was captain of the French corvette Le Rhin (1842-1846), which brought back the type specimen to France where Duvernoy analyzed it; the species name honors Maurice Arnoux, the ship's surgeon who found the skull of the type specimen on a beach near Akaroa, New Zealand.^[12] Baird's beaked whale was first described by Leonhard Hess Stejneger in 1883 from a four-toothed skull he had found on Bering Island the previous year. The species is named for Spencer Fullerton Baird, a past Secretary of the Smithsonian Institution.^[13]

Researchers have debated over whether the northern and southern populations represent distinct species or whether they are simply geographic variants.^[14] Several morphological characters have been suggested to distinguish them, but the validity of each has been disputed;^[15][16][17] currently, it seems that there are no significant skeletal or external differences between the two forms, except for the smaller size of the southern specimens known to date.^[18][19] The morphological similarity gave rise to the hypothesis that the populations were sympatric as recently as the last Pleistocene Ice Age, approximately 15,000 years ago,^[11][20] but subsequent genetic analyses suggest otherwise.^[3] Phylogenetic analyses of the mitochondrial DNA control region (D-loop) revealed that Baird's and Arnoux's beaked whales were reciprocally monophyletic — lineages from each of the species grouped together to the exclusion of lineages from the other species. Diagnostic DNA substitutions were also found. These results are consistent with the current classification of Baird's and Arnoux's beaked whales as distinct species. Further, the degree of differentiation between the northern and southern forms of Berardius suggest that the species may already have been separated for several million years.^[3]

It is speculated that the Baird's and Arnoux's whales separated from one another after their common ancestor separated from the kurotsuchi;^[21] however, this is not certain.^[2] The Berardius sp. are deep divers that can spend long periods of time submerged below the surface of the water and thus are difficult to study.^[22][23]

Possible species

Sightings during whale watching tours and studies of stranded individuals suggest the possibility of another form of Berardius in the Sea of Okhotsk inclusive of the coast of northern Hokkaido especially around Shiretoko Peninsula and off Abashiri,^[24] or to Sea of Japan off Korean Peninsula and north pacific and Bering Sea off Alaska.^[25] These whales are generally much smaller than known species (6–7 m or 20–23 ft), darker in color, and inhabit shallow waters closer to coastal areas, enough to be trapped within fixed nets for salmon.^[26] Local whalers had called them "kurotsuchi" (= black Berardius)^[27][2] or "karasu" (= ravens); it is not known whether these terms are synonyms or identify two separate species.^[2] Genetic studies indicate that kurotsuchi are Berardius minimus, recognized as a distinct species in the 2010s.^[2][21]

"Bottlenose whales in the Sea of Okhotsk" had been reported since the time of the Soviet Union's whaling,^[28] and an unknown type of beaked whale resembling Baird's beaked whales having four tusks on upper and lower jaws has also been recorded by traditional whalers in Japan.^[29] It is unknown whether these records correspond with this new form.

An unknown type of large beaked whale of similar size to fully grown Berardius bairdii have been reported to live in the Sea of Okhotsk, somewhat resembling Longman's beaked whale. The "Moore's Beach monster", an initially unidentified carcass found in 1925 on Moore's Beach on Monterey Bay, was identified by the California Academy of Sciences as a Baird's beaked whale.^[30][31] There have been claims that records of strandings of these whales exist along the areas within and adjacent to Tatar Strait in the 2010s.^[32]

Physical description

Size of Baird's beaked whale compared to an average human

Size of Arnoux's beaked whale compared to an average human

Size of Sato's beaked whale compared to a human

The two established species, Baird's and Arnoux's beaked whales, have very similar features and would be indistinguishable at sea if they did not exist in disjoint locations.^[33] 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.^[33][34][4] The Baird's and Arnoux's beaked whales are the only whales in the Ziphiidae family where both sexes have erupted teeth.^[35] The teeth in the Ziphiidae are presumed to be used by the males for fighting and competition for females. Ziphiidae has the most prevalent and pronounced markings caused by teeth scaring among the cetaceans.^[35] Front-facing teeth may be covered in barnacles after many years.^[34]

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 body.^[34] 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.^[35] These traits are similar in both sexes, as there is little sexual dimorphism in either species.^[33][34] Among the observed differences in the sexes is their size: female Baird's and Arnoux giant beaked whales are slightly larger than the males.^[35]

Although fairly similar, there exist some differences between the species. Baird's beaked whales are around 4.6 metres (15 ft) when born, and can reach lengths of 11.1 metres (36 ft) as adults, making them the largest members of the beaked whale family. Members of the Baird's species have fairly narrow body shapes despite their large size, and have dorsal fins that are rounded at the tips. Their coloration is fairly uniform and can range from brown to grey.^[34] Arnoux's beaked whales are around 4 metres (13 ft) long as calves and can reach lengths up to 9.75 metres (32 ft) as adults.^[33] Their bodies are not as narrow as the Baird's, and resemble a spindle. Unlike the Baird's beaked whale, Arnoux's have slightly hooked dorsal fins.^[33] Arnoux's beaked whales have a dark coloration that ranges from brown to orange due to a buildup of algae on its body.^[33]

A third species, B. minimus, (known by the Japanese common name "kurotsuchi", which means "black Berardius") was formally named in 2019,^[2][36] after being distinguished in 2016, based on differences in haplotypes from mtDNA.^[37] It generally has a short beak (~4% body length). While other four-toothed whales are generally grey with scars, kurotsuchis usually have few linear scars, so that the dark, smooth skin contrasts highly with round, white scars of about 5 cm diameter (from cookiecutter shark bites).^[38] The tip of the rostrum is also white. The kurotsuchi is shorter than other four-toothed whales, around 6–7 metres (20–23 ft) long at maturity, hence the species name, B. minimus (="smallest"). No females of this species have yet been described in the research literature.^[2]

Population and distribution

The total population is not known for two of the three species. Estimates for Baird's are of the order of 30,000 individuals. Nothing is known at all about the population size of the third species of Berardius, first scientifically described in the 2010s.^[38][2] Baird's and Arnoux's beaked whales have an allopatric (non-overlapping) antitropical distribution;^[39] kurotsuchis are known to live in the North Pacific.^[2]

Arnoux's

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.^[39] 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.^[40] 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.

Baird's

Baird's beaked whale is found in the North Pacific Ocean, the Sea of Japan and the southern part of the Sea of Okhotsk.^[41] They appear to prefer seas over steep cliffs at the edge of the continental shelf, but are known to migrate to oceanic islands and to near shore waters where deep cliffs locate next to landmasses such as at Rishiri Island and in Tsugaru Strait, Shiretoko Peninsula, Tokyo Bay, and Toyama Bay.^[34]

The continental shelf was reported in the Alaska stock report as the whales migrate to the shelf in the summer months during when the water temperature are at the highest.^[42] According to the California/Oregon/Washington NOAA stock assessment report the Baird's beaked whales can be found in the deep waters along the continental slopes of the North Pacific Ocean.^[11][43][44] They are often seen along the slope between late spring to early fall.

Specimens have been recorded as far north as the Bering Sea and as far south as the Baja California Peninsula.^[45][43] They are also found on the east side and the southern islands (Izu and Bonin Islands) of Japan on the west although it is unclear whether records at these islands are of Berardius bairdii. Southern limits of historical occurrences in east Asian were unclear, while there had been either a stranding or a catch in East China Sea at Zhoushan Islands in the 1950s,^[46][47] and was a disentanglement at Kamae, Ōita.^[48] Whales off the east coast of North America seems to approach coasts less frequently than in the western North Pacific, but they may travel further south than in Japan. Historical distributions of southward migrations or vagrants in Asian waters are unknown as the whales wintering from Bōsō Peninsula and in Tokyo Bay to Sagami Bay and around Izu Ōshima have been severely depleted or nearly wiped out by modern whaling (recently whalers shifted their major hunting grounds from Bōsō Peninsula to further north due to the very small numbers of whales still migrating to the former habitats). Within the Sea of Japan, the first scientific approaches to the species were made in Peter the Great Gulf, and the whales can widely distribute more on Japanese archipelago from west of Rebun Island to west of Oki Islands on unknown regularities, and major whaling grounds were in Toyama Bay and Oshima Peninsula.^[49][47]

The historic and current status of the northern species in northwestern coastal Pacific outside the Japanese EEZ are vague, especially within North and South Korea and China. Some groups still survive in the Japanese archipelago but are under serious threat by commercial whaling activities. The species is not thought to occur in Chinese waters (or at least is not resident), and the origin of a skeletal specimen at the Zhejiang Museum of Natural History, although claimed to be national, is unreliable.^[50] However, archaeological and capture records by Japanese whalers suggest that there may have been historical migrant groups of Baird's beaked whales that once regularly reached the Yellow and Bohai Seas, especially around the island of Lingshan off Jiaozhou Bay and off Dalian, at least until the mid-16th century, until being wiped out by Japanese whalers.^[51] This may have included regions at least as far south as the Zhoushan archipelago.^[46] See also Wildlife of China for natural histories of large cetaceans in this region. 12 individuals were caught as by-catch along the east coasts of the Korean Peninsula between 1996 and 2012.^[52] Canada; Japan; Korea, Democratic People's Republic of Korea; Mexico; Russian; United States, (Taylor et al. 2008). Endemic to the North Pacific Ocean and the adjacent seas. There are two different stocks of Baird beaked whales that the National Oceanic and Atmospheric Administration (NOAA) keeps track of for management of the species, the Alaska stock and the California-Oregon-Washington stock. (NOAA website). According to the Alaska 2017 stock report, the range of the Baird's beaked whale is north of the Cape Navarn (62^o N) and Central Sea of Okhotsk (57^o N) that spans to St. Matthew Island, the Pribilof Islands, and the northern Gulf of Alaska. (Alaska Stock assessment report and Balcomb 1989).

The seasonal distribution can be observed when the Baird's beaked whales spend the summer months in the Sea of Okhotsk and the Bering Sea between April–May to October. (Tomilin 1957, Kasuya 2002, Alaska Stock assessment report 2017). The wintering habitats is assumed to be located in the northern Gulf of Alaska which was determined by using acoustic detection, (Baumann-Pickering et al. 2012b. and Alaska Stock assessment report 2017.)

Sato's

B. minimus is currently known to reside in only the central and western North Pacific Ocean. The species' range includes portions of Japan, Russia, and Alaska, between 40°N and 60°N and 140°E and 160°W. However, this distribution is based primarily on data collected from stranded specimens, and its range may extend further.^[2][38][10]

Behavior

Skeleton of Berardius arnuxii, showing a skull adapted to vocalizations

Little is known about the behavior of Arnoux's beaked whale, but it is expected to be similar to that of Baird's. Distinctions between the two species are so slight that they are speculated to be the same, although genetic makeup and geographic distribution offer evidence otherwise.^[3] Baird's beaked whales generally move in pods of 5 to 20 individuals, with groups of 50 observed in rarer circumstances.^[53] Congregating groups of Baird's whales are led by a single large male. Scarring among males indicate competition for this leadership position that must entail more breeding opportunities and gives evidence that the species' behaviors portray sexual selection.^[54] Potentially one of the deepest diving cetaceans, they can dive for an hour at a time, predating on deep-water and bottom-dwelling fish, cephalopods, and crustaceans. When not diving, they drift along the surface.^[22] The deep diving whales can dive to depths of 800–1,200 metres (2,600–3,900 ft), and when feeding, they generally prefer deep waters near the continental shelf or around seamounts, where high biological activity is present in shallower waters.^[55] The deepest recorded dive is 1,777 metres (5,830 ft).^[56][57]

Diel variation in behavior suggests that beaked whales spend less time at the surface during the day than they do at night, so as to avoid surface predators like sharks and killer whales.^[58] Considering the extent of whaling on the Baird's species, the pod's uninfluenced structure is not well known. To date, two-thirds of the whales caught have been male, despite the fact that females are somewhat larger than males and would be thought to be the preferred targets for whalers.^[35] They are listed as least concern under the IUCN Red List^[8] and not listed as depleted under the MMPA.^[44] They are not being hunted for research due to Japan pulling out of the whaling commission in 2018/2019.

Observations of Arnoux's beaked whales in Doubtful Sound, New Zealand in the same seasons in 2009^[59] and in 2010^[60] indicate that this species may possess a form of bond to locations similar to those of other species such as right whales. Another 4 or 5 sightings have been recorded in the Doubtful Sound between 2007 and in 2011.^[61][62] Underwater recordings, made in the austral summer in the Antarctic of a large group of 47 Arnoux's beaked whales showed that they were highly vociferous animals at this time. The whales produced clicks, click trains, and frequency modulated pulses and whistles which gives their vocalizations a characteristic warbling aural impression.^[39] The group swam in coordinated positions along the ice edge, some of them splitting and reassembling.^[39]

Reproduction

Mating in Baird's beaked whales happens in the months of October and November and calving occurs in March and April after a 17-month gestational period.^[54] Scarring among males indicate competition for leadership position that must entail more breeding opportunities and gives evidence that the species' behaviors portray sexual selection.^[54][35] The sex ratio seems to be skewed in favor of males from observational data; with some observations indicating as high is 3:1.^[63] Males are recorded to live longer. Males live 39 years longer than females with the adult sex ratio strongly biases toward males and the female's exhibit high annual ovulation.^[35] It is possible that these results are seasonal abundances of different sexes in the region studied. They exhibit a slight reverse sexual dimorphism with females tending to be larger than males in size. The females have no post-reproductive stage.^[64][35] Cetaceans in general have an interbirth interval which is the time between births of new calves. The mysticetes tend to have two or three years or relative to body size intervals whereas the odontocete interbirth intervals are more varied.^[35] Baird beaked whales have interbirth intervals similar to mysticeti to their size than they do with other odontocetes.^[35] In July 2006, in the Sea of Cortez, Mexico, there was summer stranding event of 10 males of mixed age composition that was highly suggestive of male alloparental care.^[65][45] Females are slightly larger than the males and exhibit high annual ovulation and pregnancy rates. Males live about 30 years longer than the females with this sex ratio biased toward males it is speculated that the males provide alloparetnel care to offspring which in turn allows the females to have a shorten birth interval frequency.^[35]

Feeding

Baird's beaked whale has a diet that consists primarily of deep sea fish and cephalopods found at its preferred dive depths (1000–1777m).^[56][57] On rare occasions, it has been known to eat octopus, lobster, crab, rockfish, herring, starfish, pyrosomes and sea cucumbers.^[41] Baird's beaked whales in the southern Sea of Okhotsk diet consists of deep-water gadiform fishes and cephalopods.^[41] The species has a mean dive time of about 1 hour, which suggests a long search and handling time.^[42][41] Its generalist feeding strategy may be reflective of limited prey availability at such depths or regions, as mammals become more general feeding strategists as prey diversity decreases. It may also explain the species' migrational patterns around the North Pacific.^[41] In summer months, Baird's beaked whale can be found off the Pacific coast of Japan where demersal fish are abundant.^[41] Stomach content analysis's found that Baird's beaked whale feeds in benthic zones both day and night. This behavior differs from its other Odontocete relatives (namely the common dolphin and Dall's porpoise) who feed in mesopelagic regions during the day when the light can penetrate the water column.^[66] This suggests that Baird's beaked whale does not rely as much on its sense of sight and has evolved to navigate and hunt competently with echolocation.^[67] There is little information on the foraging behavior of Baird's beaked whales and their ecological role in the marine ecosystem.^[41]

Conservation

Baird's Beaked Whale at a shore station in Japan, 1982

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).^[68]

Baird's beaked whale is listed by the Mammalogical Society of Japan as rare in Japanese coastal waters. The Baird's beaked whale is listed on Appendix II^[69] of the convention on the Conservation of Migratory Species of Wild Animals (CMS). It is listed on Appendix II^[69] as it has an unfavorable conservation status or would benefit significantly from international co-operation organised by tailored agreements. It is considered Least Concern by the IUCN.^[8] They are not listed as "threatened" or "endangered" under the endangered species act nor depleted under the MMPA.^[44] There is preliminary evidence of the Baird's beaked whale being sensitive to anthropogenic aquatic noise pollution, as other odontocete species are.^[70][71] Anthropogenic sound sources such as military sonar and seismic testing. The testing of military sonar has been recorded to effect the diving behavior of beaked whales. This implication on the whales effects their ability to decompress upon surfacing and results in the whales suffering the bends, increase nitrogen gas bubbles in the blood.^[22][44]

In the 20th century, Baird's beaked whales were hunted primarily by Japan and to a lesser extent by the USSR, Canada and the United States. The USSR reported killing 176 before hunting ended in 1974. Canadian and American whalers killed 60 before halting in 1966. Japan killed around 4000 individuals before the 1986 moratorium on whaling (about 300 were killed in the most prolific year, 1952). Baird's beaked whales are not protected under the International Whaling Commission's moratorium on commercial whaling, as Japan argues they are a 'small cetacean' species, despite being larger than minke whales, which are protected. Each year, 62 Baird's beaked whales are hunted commercially in Japan, with the meat sold for human consumption. A landing and processing of a Baird's beaked whale was filmed^[72] by the Environmental Investigation Agency on 7 August 2009. Meat and blubber food products of the whales have been found to contain high levels of mercury and other pollutants, such as polychlorinated biphenyls (PCBs).

Population status

Estimates of the abundance of populations are unavailable.^[44] They are not listed as "threatened" or "endangered" under the endangered species act nor depleted under the MMPA.^[44]

Threats

The Baird's beaked whale is hunted by Japan. As of 2019, Japan pulled out of the International Whaling Commission (IWC) to continue harvesting whales commercially.^[73] The California large mesh drift gillnet fishery has known to interact with the CA-OR-WA population. There are habitat concerns for the Alaska stock, in areas with oil and gas activities or shipping and military activities are high.^[44] For the Baird's beaked whale.^[74][75][76] Anthropogenic sound sources such as military sonar and seismic testing. The testing of military sonar has been recorded to effect the diving behavior of beaked whales. This implication on the whales effects their ability to decompress upon surfacing and results in the whales suffering the bends, increase nitrogen gas bubbles in the blood.^[22][44]

Common names

Some traditional Japanese hammers

• B. arnuxii is known as Arnoux's beaked whale, southern four-toothed whale, southern beaked whale, New Zealand beaked whale, southern giant bottlenose whale, and southern porpoise whale. In Japanese it is known as minami-tsuchi (ミナミツチ), literally "Southern hammer (i.e. Berardius)".
• B. bairdii is known as Baird's beaked whale, northern giant bottlenose whale, North Pacific bottlenose whale, giant four-toothed whale, northern four-toothed whale, and North Pacific four-toothed whale. In Japanese, it is called tsuchi-kujira　(ツチクジラ), where tsuchi means "hammer", in reference to the way the head vaguely resembles a traditional Japanese hammer or mallet, and kujira means "whale".^[77]
• The newly described species, B. minimus, is traditionally known to Japanese whalers as kuro-tsuchi (黒ツチ),^[2] where kuro means "black" and tsuchi means "hammer".^[77] The Society for Marine Mammalogy lists Sato's beaked whale as an additional common name for B. minimus.^[78]

Specimens

• MNZ MM002654 B. arnuxii Arnoux's beaked whale, collected Riverton, near Invercargill, New Zealand, 27 January 2006

See also

• List of cetaceans

References

• "Giant Beaked Whales" in the Encyclopedia of Marine Mammals pages 519-522 Teikyo Kasuya, 1998. ISBN 0-12-551340-2
• National Audubon Society Guide to Marine Mammals of the World Reeves et al., 2002. ISBN 0-375-41141-0.
• Whales, Dolphins and Porpoises Carwardine, 1995. ISBN 0-7513-2781-6
• An image of a Baird's Beaked Whale at monteraybaywhalewatch.com

Gigantaj bekobalenoj estas du specioj de bekobalenoj en la genro Berardius: la Arnuksa bekobaleno (Berardius arnuxii) en malvarmaj akvoj de Suda Hemisfero, kaj la Bairda bekobaleno (Berardius bairdii) en malvarm-moderaj akvoj de la Norda Pacifiko. Ebla nenomita tria specio estis priskribita en 2016. Ili estas la plej grandaj balenoj kiuj apartenas al la familio de Zifiedoj. Ĉirkaŭkalkuloj de vivodaŭro, baze sur orelvaksaj montroj, indikas, ke tiuj balenoj povas vivi ĝis 85 jaroj.^[1] Ili estas foje referencata kiel "kvar-dentaj balenoj" aŭ "gigantaj bekobalenoj", sed estas plej ofte konata pere de sia genronomo, Berardius. La Arnuksa kaj la Bairda bekobalenoj estas tiom similaj ke esploristoj debatis ĉu aŭ ne temas pri simple du populacioj de la sama specio. Tamen, genetika pruvaro kaj ilia ampleksa geografia separado kondukis ilin esti klasita kiel apartaj specioj.

Fizika priskribo

Grando de Bairda bekobaleno kompare kun averaĝa homo.

Grando de Arnuksa bekobaleno kompare kun averaĝa homo.

Ambaŭ establitaj specioj havas tre similajn trajtojn kaj estus nedistingeblaj mare se ili ne ekzistus en disaj lokoj.^[2] Ambaŭ balenoj atingas similajn grandojn, havas bulbajn melonojn, kaj longajn elstarajn bekojn. Ties malsupra makzelo estas pli longa ol tiu supra, kaj la antaŭaj dentoj estas videblaj eĉ kiam la buŝo estas tute malferma.^[2][3] Tio povas rezulti en havo de antaŭaj dentoj kovritaj per ciripeduloj post multaj jaroj.^[3] La Bairda bekobaleno kaj la Arnuksa bekobaleno ankaŭ havas similformajn malgrandajn naĝilojn kun rondoformaj pintoj, kaj malgrandajn dorsajn naĝilojn kiuj kuŝas tre for dorse en la korpo. Plenkreskaj maskloj kaj inoj de ambaŭ specioj montras nombrajn blankajn liniajn cikatrojn tra la tuta korpo dum ili pliaĝas, kaj tio povas esti ioma indikilo de aĝo. Tiuj trajtoj estas similaj en ambaŭ seksoj ĉar estas malmulta seksa dimorfismo en ambaŭ specioj.^[2][3]

Kvankam tre similaj, estas kelkaj diferencoj inter ambaŭ specioj. Bairdaj bekobalenoj estas ĉirkaŭ 4.6 metrojn dumnaske, kaj povas atingi longojn de 11.1 metrojn jam plenkreskaj, kio faras ilin la plej grandaj membroj de la familio de bekobalenoj. Bairdaj havas iom mallarĝajn korpoformojn spite ties grandon, kaj havas dorsajn naĝilojn kiuj estas rondoformaj pinte. Ties koloraro estas sufiĉe uniforma kaj povas gami el bruna al griza.^[3] La Arnuksaj bekobalenoj estas ĉirkaŭ 4 metrojn dumide, povas atingi longojn de ĝis 9.75 metroj jam plenkreskaj. Ties korpoj estas ne tiom mallarĝaj kiom la Bairdaj, kaj similas ŝpinilo. Malkiel la Bairdaj, la Arnuksaj bekobalenoj haas iom hokoformajn dorsajn naĝilojn. Arnuksaj bekobalenoj havas malhelan koloraron kiu gamas el bruna al oranĝa pro la akumulo de algoj en sia korpo.^[2]

Notoj

1. ↑ "Berardius bairdii". The Moirai - Aging Research. 2016-10-19. Alrita la 7an de Novembro 2018.
2. ↑ ^{2,0 2,1 2,2 2,3} http://us.whales.org/species-guide/arnouxs-beaked-whale
3. ↑ ^{3,0 3,1 3,2 3,3} "Baird's beaked whale", WDC, Whale and Dolphin Conservation. (angle)

Bibliografio

• Giant Beaked Whales in the Encyclopedia of Marine Mammals pages 519-522 Teikyo Kasuya, 1998. ISBN 0-12-551340-2
• National Audubon Society Guide to Marine Mammals of the World Reeves et al., 2002. ISBN 0-375-41141-0.
• Whales, Dolphins and Porpoises Carwardine, 1995. ISBN 0-7513-2781-6

Berardius (también llamado Berardios) es un género de cetáceos odontocetos de la familia Ziphidae que incluye a los zifios de mayor tamaño y ballenas de cuatro dientes. Este género incluye el zifio de Arnoux (Berardius arnuxii, o minami-tsuchi) en aguas frías del hemisferio sur, y el zifio de Baird (Berardius bairdii, o tsuchi-kujira) en aguas frías y templadas del Pacífico Norte. Una tercera especie, el zifio negro (Berardius minimus o ballena menor de cuatro dientes, kuro-tsuchi o zifio de Sato) se declaró distint a de los zifios de Baird en la década de 2010.^[1]​

Los zifios de Arnoux y de Baird son tan similares que los investigadores han debatido si se trata o no simplemente de dos poblaciones de la misma especie. Sin embargo, pruebas genéticas y su amplia separación geográfica han llevado a clasificarlas como especies separadas.^[2]​Con base en muestras de tapones de cera en sus oídos, se cree que los zifios de Baird pueden vivir hasta 85 años.^[3]​Con una longitud de aproximadamente 4 m al nacer, y llegando a crecer hasta alrededor de los 10 m, los zifios de Arnoux y Baird son las ballenas más grandes pertenecientes a la familia Ziphiidae. El kurotsuchi o zifio negro es mucho más pequeño, y los machos adultos tienen una longitud de aproximadamente 7 m.

Especies

El género Berardius se clasificaba en el pasado como una especie que sólo tenía dos especies: El zifio de Arnoux (Berardius arnuxii) en las aguas del Hemisferio Sur, y el zifio de Baird (Berardius bairdii) en el Pacífico Norte. El zifio de Arnoux fue descrito por Georges Louis Duvernoy in 1851. El nombre del género proviene del almirante Auguste Bérard (1796-1852), quien era el capitán de la corbeta francesa Le Rhin (1842-1846), en la que se llevó un espécimen a Francia para que Duvernoy lo analizara, mientras que el nombre de la especie es en honor a Maurice Arnoux, el cirujano del navío que encontró el cráneo del espécimen en una playa cerca de Akaroa, Nueva Zelanda.^[4]​ El zifio de Baird fue descrito por primera vez por Leonhard Hess Stejneger en 1883 a partir de un cráneo que encontró en la isla de Bering el año previo. La especie recibe su nombre en honor a Spencer Fullerton Baird, un secretario del Instituto Smithsoniano.^[5]​

Los investigadores han debatido sobre si las poblaciones del norte y del sur representan especies distintas o si son simplemente variantes geográficas.^[6]​ Se han sugerido varios caracteres morfológicos para distinguirlas, pero la validez de cada uno de ellos es motivo de debate;^[7]​^[8]​^[9]​en la actualidad, no parece haber diferencias esqueléticas o externas significativas entre las dos formas, salvo el menor tamaño de los ejemplares del sur conocidos hasta la fecha.^[10]​^[11]​La similitud morfológica dio origen a la hipótesis de que las poblaciones eran simpátricas desde la última Era de Hielo del Pleistoceno, hace aproximadamente 15.000 años, pero análisis genéticos posteriores sugieren lo contrario.^[12]​Análisis filogenéticos de la región de control del ADN mitocondrial (bucle D o D-loop) revelaron que los zifios de Baird y de Arnoux eran recíprocamente monofiléticos: linajes de cada una de las especies se agrupaban excluyendo linajes de la otra especie. También se hallaron sustituciones diagnósticas en el ADN. Estos resultados son consistentes con la actual clasificación de los zifios de Baird y de Arnoux como especies distintas. Además, el grado de diferenciación entre las formas septentrionales y meridionales del género Berardius sugiere que las especies pueden haber estado separadas ya desde hace varios millones de años.^[12]​

La evidencia genética sugiere que los zifios de Baird y de Arnoux se separaron unos de los otros después de que su ancestro común se separara de los zifios negros,^[13]​aunque no existe certeza a este respecto.^[14]​ Son especies que nadan a grandes profundidades y que pasan largos periodos de tiempo sumergidas bajo la superficie del agua, por lo que son difíciles de estudiar.^[15]​^[16]​Se les considera parte de los odontocetos más pequeños en cuanto a tamaño total.^[17]​

Posibles especies

Avistamientos durante excursiones de observación de ballenas y estudios de individuos varados sugieren la posibilidad de otra forma de Berardius en el Mar de Ojotsk, incluyendo la costa del norte de Hokkaido, especialmente alrededor de la península de Shiretoko y cerca de Abashiri,^[18]​o en el Mar del Japón frente a la península de Corea y el Pacífico Norte y el Mar de Bering frente a Alaska.^[19]​Estas ballenas son generalmente mucho más pequeñas que las especies conocidas (6-7 m), de color más oscuro, y habitan en aguas poco profundas cerca de las zonas costeras, lo suficiente como para quedar atrapadas en las redes fijas para pescar salmón.^[20]​Los balleneros locales las llaman "kurotsuchi" (Berardius negro) o "karasu" (que significa cuervo); no se sabe si estos términos son sinónimos o identifican dos especies distintas.^[21]​Estudios genéticos indican que los kurotsuchi son zifios negros (Berardius minimus), reconocidos como especie distinta en la década de 2010.^[21]​^[22]​

Desde la época de la caza de ballenas por parte de la Unión Soviética se ha reportado la existencia de zifios calderones del norte en el Mar de Ojotsk,^[23]​y los balleneros tradicionales de Japón también han reportado un tipo desconocido de zifio parecido al zifio de de Baird que tiene cuatro colmillos en las mandíbulas superior e inferior.^[24]​Se desconoce si estos registros se corresponden con esta nueva forma.

Se ha reportado que en el Mar de Ojotsk vive un tipo desconocido de gran zifio de tamaño similar al de un zifio de Baird adulto, que se asemeja en cierto modo al zifio de Longman. El "monstruo de la Playa Moore", un cadáver inicialmente no identificado que se encontró en 1925 en la Playa Moore, en la bahía de Monterrey, fue identificado por la Academia de Ciencias de California como un zifio de Baird..^[25]​^[26]​Se ha afirmado que existen registros de varamientos de estas ballenas a lo largo de las áreas dentro y alrededor del Estrecho de Tartaria en la década de 2010.^[27]​

Especies conocidas

• Berardius arnuxii (zifio de Arnoux);
• Berardius bairdii (zifio de Baird);
• Berardius minimus (zifio negro).

Notas

Referencias

• Wilson, D. E. & Reeder, D. M. (eds.), 2005. Mammal Species of the World. A Taxonomic and Geographic Reference (3rd ed)
• IUCN - Berardius arnuxii
• IUCN - Berardius bairdii

Berardius Ziphiidae familiako generoa da. Lehenengo espezimena eraman zuen Auguste Bérard (1796-1852) frantziar kapitainaren omenez izendatu zuten.

Espeziak

• Berardius arnuxii
• Berardius bairdii

Le genre Berardius comporte trois espèces de baleine à bec, la bérardie d’Arnoux (Berardius arnuxii), Berardius minimus et la bérardie de Baird (Berardius bairdii). Ce sont les plus grandes de toutes les baleines à bec et on parle parfois d’elles comme des baleines à bec géantes.

Systématique

La bérardie d'Arnoux et la bérardie de Baird sont si semblables que certains scientifiques^[2] considèrent leur séparation comme une anomalie historique. Elles seraient indistinguables en mer si leurs aires de répartition n’étaient pas complètement distinctes.

Le nom du genre a été donné en hommage à Auguste Bérard, le capitaine de la corvette Le Rhin qui ramena de Nouvelle-Zélande à Louis Georges Duvernoy le premier crâne à être décrit.

Description

Elles ont un bec particulièrement long et proéminent, y compris par rapport aux autres genres de baleines à bec. La mâchoire inférieure est plus longue que la supérieure et les dents de devant sont visibles y compris quand la bouche est complètement fermée. Le front est bulbeux. Le corps est svelte, la circonférence représentant seulement 50 % de la longueur. La couleur est uniforme mais peut varier d’un individu à l’autre du gris clair au noir. Les nageoires pectorales sont petites et arrondies et sont disposées vers l’avant du corps. La nageoire dorsale, petite et arrondie également, est située aux trois-quarts du corps. Les bérardies portent sur toute la surface du corps de nombreuses cicatrices blanches qui peuvent être un bon indicateur de l’âge de l’animal. Le dimorphisme sexuel est très faible (les femelles sont légèrement plus grandes que les mâles).

Liste des espèces

• Berardius arnuxii Duvernoy, 1851 - bérardie d’Arnoux ou baleine à bec d'Arnoux
• Berardius bairdii Stejneger, 1883 - bérardie de Baird ou baleine à bec de Baird
• Berardius minimus Tadasu K. Yamada,2019 - Kurotsuchikujira en japonais

• Berardius arnuxii

• Berardius bairdii

• Berardius minimus

Références

Giant Beaked Whales in the Encyclopedia of Marine Mammals pages 519-522 Teikyo Kasuya, 1998. (ISBN 0-12-551340-2)

Notes et références

Is ainmhí é an míol mór socach Baird. Mamach atá ann.

Is síol ainmhí é an t-alt seo. Cuir leis, chun cuidiú leis an Vicipéid.
Má tá alt níos forbartha le fáil i dteanga eile, is féidir leat aistriúchán Gaeilge a dhéanamh.

Berardius é un xénero de cetáceos odontocetos da familia dos zifíidos que inclúe os zifios de maior tamaño.

Etimoloxía

O xénero Berardius foi establecido polo médico e zoólogo francés Louis Georges Duvernoy,^[4] quen lle puxo este nome na honra do mariño Auguste Bérard, capitán da corveta Le Rhin, que lle enviara a Duvernoy, desde Nova Zelandia, o primeiro cranio descrito.

Descrición

Teñen un bico particularmente longo e prominente en relación cos outros zifios. A mandíbula inferior é máis longa que a superior e os dentes dianteiros son visíbei mesmo coa boca pechada. O corpo é esvelto, coa sección máxima só dun 50 % da lonxitude total. A fronte é abombada, debido á presenza do melón na cabeza. A coloración é uniforme, pero podo variar segundo os individuos desde a gris clara á negra. As aletas pectorais son pequenas e arredondadas e están situadas cara á parte dianteira do corpo. A aleta dorsal, así mesmo pequena e arrondada, sitúase ao comezo do último terzo do corpo. Levan en toda a superficie do corpo numerosas cicatrices brancas que poden ser un bo indicador da idade do animal. O dimorfismo sexual é escaso.

Especies

O xénero comprende tan só dúas especies:

• Berardius arnouxii Duvernoy, 1851 - zifio de Arnoux
• Berardius bairdii Stejneger, 1883 - zifio de Baird

As dúas especies son tan parecidas que algúns científicos consideraron a súa separación como unha anomalía histórica. Serían indistinguíbeis no mar se as súas áreas de distribución non foran completamente diferentes.^[5]

Áreas de distribución

• Mapa de distribución do zifio de Arnoux

• Mapa de distribución do zifio de Baird

Dúas especies

Pero a falta de diferenzas morfolóxicas coñecidas pode ser simplemente debido ao escaso número de espécimes examinados (especialmente do zifio de Arnoux), e análises de datos da secuencia dos intróns mitocondrial e nuclear revelaron diferenzas xenéticas, confirmando que estas especies son entidades taxonómicas reprodutivamente illadas e válidas.^[6][7]

Estado de conservación

Para a IUCN, o estado de conservación de ambas as especies é sen datos suficientes (CC).^[7][8]

Notas

Véxase tamén

Bibliografía

• Perrin, William F., Bernd Würsig & J. G. M. Thewissen (eds.) (2002): Encyclopedia of Marine Mammals. 2ª ed. San Diego: Academic Press. ISBN 978-0-12-373553-9
• Wilson, D. E. & Reeder, D. M. (eds.) (2005): Mammal Species of the World. A Taxonomic and Geographic Reference. Third edition. ISBN 0-8018-8221-4.

Outros artigos

• Cetáceos
• Odontocetos
• Zifíidos

Berardius è un genere di cetacei odontoceti appartenente alla famiglia degli Zifidi. Comprende tre specie, il berardio australe (B. arnuxii), quello boreale (B. bairdii) e il berardio di Sato (B. minimus). Le prime due specie sono così simili che alcuni scienziati^[1] considerano la separazione in due specie come un'anomalia storica. Le due specie sono le più grandi fra tutte quelle appartenenti agli Zifidi.

Il berardio boreale venne descritto per la prima volta da Leonhard Hess Stejneger nel 1883 a partire da un esemplare trovato nel Mare di Bering. L'epiteto specifico bairdii gli è stato assegnato in onore di Spencer Fullerton Baird, un ex Segretario dello Smithsonian Institute. Il berardio australe venne descritto per la prima volta nel 1851 da Duvernoy a partire da un cranio trovato in Nuova Zelanda. Berard era il capitano della nave che trasportò il cranio dalla Nuova Zelanda alla Francia dove Duvernoy lo analizzò. Arnoux era il medico di bordo della nave, e da lui deriva l'epiteto specifico arnuxii.

Descrizione fisica

La specie australe è generalmente più piccola. Le lunghezze stimate dei berardi australi vivi in mare raggiungono i 12 m, ma tutti gli esemplari morti sono generalmente più piccoli. Per quanto riguarda quelli boreali, invece, è stato confermato che raggiungano i 12–13 m.

Entrambe le specie hanno un rostro prominente molto lungo, persino per gli standard degli Zifidi. La mascella inferiore è più lunga della superiore e i denti frontali sono visibili anche quando la bocca è completamente chiusa. Il melone è particolarmente bulboso. La forma del corpo è snella - il ventre è solo il 50% della lunghezza. Il corpo ha una colorazione uniforme e a seconda degli individui può variare tra il grigio chiaro e il nero. Le pinne pettorali sono piccole, arrotondate e situate verso il davanti del corpo. Similmente la pinna dorsale è piccola e arrotondata e situata verso i tre quarti della linea del dorso. Entrambe le specie presentano numerose cicatrici bianche su tutto il corpo che aumentano di numero con gli anni e possono essere usate come un semplice indicatore di età. Esiste un piccolo dimorfismo sessuale in entrambe le specie.

Popolazione e distribuzione

Gli areali delle due specie non si sovrappongono e questa, forse, è la ragione principale per cui storicamente sono state considerate come specie separate.

L'australe abita le grandi estensioni dell'Oceano Meridionale. Gli spiaggiamenti in Nuova Zelanda e in Argentina indicano che questo cetaceo è relativamente comune nelle aree tra il sud di questi paesi e l'Antartide. È anche stato segnalato nei pressi della Georgia Australe e del Sudafrica, cosa che indica una probabile distribuzione circumpolare. L'avvistamento più settentrionale è avvenuto a 34 gradi sud, indicando che questa odontoceto abita acque fredde e temperate così come quelle polari.

Il berardio boreale vive nell'Oceano Pacifico settentrionale, nel Mar del Giappone e nella parte meridionale del Mare di Okhotsk. Sembra che prediliga le aree sovrastanti le scogliere scoscese ai margini della piattaforma continentale. Gli esemplari più a nord sono stati registrati nel Mare di Bering e quelli più a sud nella Penisola della Baja California sul lato orientale e nelle isole meridionali del Giappone su quello ovest.

Di entrambe le specie è sconosciuta la popolazione totale. Per quelli boreali le stime sono dell'ordine dei 30.000 individui.

Comportamento

Conosciamo poco sul comportamento del berardio australe, ma si sostiene che sia simile a quello del boreale. Questi mammiferi si muovono normalmente in gruppi compatti di 3-10 esemplari, ma in circostanze eccezionali sono stati osservati anche gruppi di 50. Grazie all'entità della caccia subita da questa specie, la struttura dei pod è attualmente ben conosciuta. Un'interessante curiosità è che i due terzi di tutti gli esemplari catturati erano maschi, nonostante il fatto che le femmine sono un po' più grandi dei maschi, cosa che le avrebbe rese il bersaglio preferito dei balenieri, se fossero state altrettanto facili da catturare.

Conservazione

Il berardio australe non è mai stato sfruttato e sebbene non sia disponibile alcuna stima del loro numero, la popolazione non è ritenuta in pericolo.

Nel ventesimo secolo il berardio boreale è stato cacciato principalmente dai giapponesi e in numero minore dai sovietici, dai canadesi e dagli statunitensi. L'URSS registrò 176 uccisioni prima che finisse la caccia, nel 1974. I balenieri canadesi e americani ne uccisero 60 prima della sospensione, nel 1966. I giapponesi uccisero 4000 individui prima della moratoria sulla caccia alla balena del 1986. Nell'anno più prolifico, il 1952, ne uccisero 300. Sotto i termini di questa moratoria sono state introdotte delle quote e attualmente ogni anno vengono uccisi 62 animali per ricerche scientifiche e la loro carne viene venduta nei mercati locali. Si crede che la specie non sia minacciata da questo livello di caccia.

Note

Bibliografia

• Giant Beaked Whales in the Encyclopedia of Marine Mammals pages 519-522 Teikyo Kasuya, 1998. ISBN 0-12-551340-2
• National Audubon Society Guide to Marine Mammals of the World Reeves et al, 2002. ISBN 0-375-41141-0.
• Whales, Dolphins and Porpoises Carwardine, 1995. ISBN 0-7513-2781-6
• An image of a Baird's Beaked Whale at monteraybaywhalewatch.com, su montereybaywhalewatch.com.
• cetacean.org on the origin of the species' names, su cetacea.org. URL consultato il 7 maggio 2006 (archiviato dall'url originale il 5 aprile 2005).

Berardius is een geslacht van walvissen uit de familie der spitssnuitdolfijnen (Ziphiidae).

Soorten

Er bestaan drie soorten in dit geslacht:

• zwarte dolfijn (Berardius bairdii)
• zuidelijke zwarte dolfijn of spitssnuitdolfijn van Arnoux (Berardius arnuxii)
• Karasu

Kjempenebbhvaler (Berardius) er ei slekt i nebbhvalfamilien (Ziphiidae) som består av kun to (kanskje tre) arter, som utbredt i henholdsvis det kalde Sørishavet og det tempererte nordlige Stillehavet. Dette er de fysisk største av nebbhvalene, som er tannhvaler (Odontoceti) med tilbakedannede tenner, som er svært fåtallige og stort sett uten betydning for artenes etefunksjoner. Slekten av kjempenebbhvaler refereres også til som firetannhvaler.

Biologi

Nordlig kjempenebbhval (B. bairdii) er utbredt i det nordlige Stillehavet

De to eksisterende artene av kjempenebbhvaler er så like at de bare kan skilles fra hverandre i sjøen på lokasjonen. Sørlig kjempenebbhval (B. arnuxii) kan bli opp mot 9,75 m lang, mens nordlig kjempenebbhval (B. bairdii) kan bli opp mot 11,1 m lang og opp til 12 tonn tung. Hannene er typisk noe mindre enn hunnene. Kalven er henholdsvis cirka 4 og 4,6 m når den blir født. Begge er i varierende grad grå til gråbrune, men det er også oppdaget en sort variant blant den nordlige arten (se taksonomi). Begge artene har et prominent snuteparti, formet som en flaskehals og gjerne referert til som et nebb (hvalnebb). Artene har dessuten en prominent pannekul, kalt en melon og assosiert med dyras biosonar (et system for ekkolokalisering).

Svært lite er kjent omkring artenes atferd, annet enn at nebbhvaler stort sett regnes som dyp-dykkere som i hovedsak livnærer seg av blekkspruter, men også eter noe dyphavsfisk og krepsdyr som de fanger (ved hjelp av ekkolokalisering) på store havdyp (nordlige kjempenebbhval typisk 800–1 200 m) i den bentiske sonen med en spesiell sugeteknikk. At disse hvalene også kalles firetannhvaler, skyldes at de kun har fire tenner i underkjeven. Tennene er uten betydning når dyra jakter og eter. Nordlig kjempenebbhval beveger seg ofte i mindre grupper på 5–20 individer, men grupper på opp mot 50 individer har blitt registrert.^[1]

Taksonomi

De to artene av kjempenebbhval er så like, at forskerne ikke har vært sikre på om det er to populasjoner av samme art eller to distinkte arter. Genetiske og geografiske forskjeller har imidlertid ført til at de nå stort sett ansees som to distinkte arter.

Mot slutten av 2016 dukket det opp ny informasjon om en sort variant, som antyder at nordlig kjempenebbhval kan være to distinkte arter. Den nordlige arten er vanligvis grå, men japanske forskere har funnet ut, at det man tidligere trodde var en sort variant, kan vise seg å være en ny og hittil uoppdaget art av kjempenebbhval, blant annet basert på forskjeller i den grå og sorte variantens mtDNA haplotyper. Japanerne kaller den sorte varianten karasu, som betyr ravn på japansk og viser til fargen. Undersøkelsen viser at den grå og sorte kjempenebbhvalen også skiller seg i størrelse, og den preliminære undersøkelsen mer enn antyder at den trolig er en distinkt art, som kan være søsterarten til de to andre kjempenebbhvalene, som altså deler en felles ane som er yngre enn den de to deler med det sorte formen.^[2]

Inndeling

Utbredelse - sørlig kjempenebbhval

(B. arnuxii)

Utbredelse - nordlig kjempenebbhval

(B. bairdii)

Det finnes flere måter å dele inn nebbhvalene på. En måte er å dele artene inn etter formen på nebbet, som nebbhvaler og spissnebbhvaler. En annen måte er å dele de inn etter sine biologiske slekter, slik det er gjort nedenfor.

Det har hersket en viss usikkerhet omkring hvorvidt sørlig kjempenebbhval og nordlig kjempenebbhval er samme art eller ikke. De listes her i henhold til CTDs klassifisering som to ulike arter i samme slekt, men noen forskere mener de kan tilhøre samme art. Det har dessuten vært knyttet stor usikkerhet til om den svært sjeldne longmanspisshvalen skal klassifiseres som i sin egen slakt, som Indopacetus pacificus, eller i slekten Mesoplodon. Nyere forskning viser imidlertid nå at denne hvalen bør klassifiseres i en egen slekt.^[3]

Inndelingen under følger revisjon 15488 av 26. juni 2018 ved Comparative Toxicogenomics Database (CTD) og er i henhold til MDI Biological Laboratory og NC State University.^[4] Inndelingen støttes også av WoRMS.^[5]

• Cetartiodactyla, hvaler og klovdyr
  • Cetacea, hvaler
    • Odontoceti, tannhvaler
      • Ziphiidae, nebbhvalfamilien
        • Berardius, kjempenebbhvaler
          • B. arnuxii, sørlig kjempenebbhval
          • B. bairdii, nordlig kjempenebbhval
        • Hyperoodon, (egentlige nebbhvaler)
          • H. ampullatus, nebbhval
          • H. planifrons, sørnebbhval
        • Indopacetus (monotypisk)
          • I. pacificus, longmanspisshval
        • Mesoplodon, spissnebbhvaler
          • M. bidens, nordspisshval
          • M. bowdoini, andrewsspisshval
          • M. carlhubbsi, buespisshval
          • M. densirostris, blainvillespisshval
          • M. europaeus, gervaisspisshval
          • M. ginkgodens, ginkgospisshval
          • M. grayi, grayspisshval
          • M. hectori, hektorsspisshval
          • M. layardii, layardspisshval
          • M. mirus, truespisshval
          • M. perrini, perrinspisshval
          • M. peruvianus, dvergspisshval
          • M. stejnegeri, stejnegerspisshval
          • M. traversii, bahamondespisshval
        • Tasmacetus (monotypisk)
          • T. sheperdi, tasmansk nebbhval
        • Ziphius (monotypisk)
          • Z. cavirostris, gåsenebbhval

Referanser

Eksterne lenker

• (en) Kjempenebbhvaler – oversikt og omtale av artene i WORMS-databasen
• (en) Kjempenebbhvaler i Encyclopedia of Life
• (en) Kjempenebbhvaler i Global Biodiversity Information Facility
• (en) Kjempenebbhvaler hos Fossilworks
• (en) Kjempenebbhvaler hos NCBI
• (en) Kjempenebbhvaler hos ITIS
• (en) Kategori:Berardius – bilder, video eller lyd på Wikimedia Commons
• Berardius – detaljert informasjon på Wikispecies

Dziobogłowiec^[3] (Berardius) – rodzaj ssaka z rodziny zyfiowatych (Ziphiidae).

Występowanie

Rodzaj obejmuje gatunki występujące w wodach półkuli południowej i w północnym Pacyfiku^[4].

Systematyka

Nazewnictwo

Nazwa rodzajowa honoruje kapitana (późniejszego admirała) francuskiej marynarki wojennej Augusta Bérarda, dowódcy korwety „Ren”, na której podczas rejsu, zebrano holotyp^[5].

Gatunek typowy

Berardius arnuxii Duvernoy, 1851

Podział systematyczny

Do rodzaju należą następujące gatunki^[3][4]:

• Berardius arnuxii – dziobogłowiec południowy
• Berardius bairdii – dziobogłowiec północny

W 2016 r. opublikowano badania genetyczne, sugerujące występowanie w północnym Pacyfiku także odrębnego, trzeciego, nie nazwanego jeszcze gatunku ^[6]. Zaliczono do niego m. in. tajemniczego martwego wala wyrzuconego w 2014 r. na brzeg Wyspy Świętego Jerzego w archipelagu Wysp Pribyłowa na Alasce ^[7].

Przypisy

Berardius é um gênero de baleias-bicudas encontrado em águas frias no Pacífico Norte e em áreas subantárticas.

• Berardius arnuxii Duvernoy, 1851 - Baleia-bicuda-de-arnoux
• Berardius bairdii Stejneger, 1883 - Baleia-bicuda-de-baird

Referências

• MEAD, J. G.; BROWNELL, R. L. (2005). Order Cetacea. In: WILSON, D. E.; REEDER, D. M. (Eds.) Mammal Species of the World: A Taxonomic and Geographic Reference. 3ª edição. Baltimore: Johns Hopkins University Press. p. 723-743.

Berardius^[1] är ett släkte i familjen näbbvalar.^[2]

Kladogram enligt Wilson & Reeder (2005)^[2]:

Arnoux' näbbval

Bairds näbbval

Hyperoodon

Indopacetus

Mesoplodon

Tasmacetus

Ziphius

Källor

1. ^ Bisby F.A., Roskov Y.R., Orrell T.M., Nicolson D., Paglinawan L.E., Bailly N., Kirk P.M., Bourgoin T., Baillargeon G., Ouvrard D. (red.) (28 april 2011). ”Species 2000 & ITIS Catalogue of Life: 2011 Annual Checklist.”. Species 2000: Reading, UK. Arkiverad från originalet den 18 juni 2012. https://web.archive.org/web/20120618223324/http://www.catalogueoflife.org/services/res/2011AC_26July.zip. Läst 24 september 2012.
2. ^ [a b] Wilson & Reeder, red (2005). ”Berardius” (på engelska). Mammal Species of the World. Baltimore: Johns Hopkins University Press. ISBN 0-8018-8221-4

Externa länkar

• Wikimedia Commons har media som rör Berardius.
  Bilder & media
• Wikispecies har information om Berardius.
  Artförteckning

Dev gagalı balina (Hyperoodon planifrons), gagalı balinagiller (Ziphiidae) familyasından Berardius cinsine ait üç balina türünden ikisi Güney yarıküre'nin soğuk sularında yaşayan Arnoux gagalı balinası ve Büyük Okyanus'un kuzeyindeki soğuk sularda bulunan Baird gagalı balinasıdır. Üçüncü bir tür 2016 yılında tanımlanmış ancak adlandırılmamıştır. Gagalı balinagillerin en büyükleri olup boyları 10-12 metreye ulaşabilmektedir. Dört dişli balina veya dev gagalı balina olarak da adlandırılsalar bile genellikle cins isimleri olan Berardius olarak bilinirler. Arnoux ve Baird gagalı balinaları o kadar birbirine benzerdir ki ayrı tür olup olmamaları tartışma konusu olmuş ancak genetik kanıtlar ve yaşadıkları coğrafyaların farklılığı nedeniyle ayrı ayrı sınıflandırılmalarına karar verilmiştir.^{[1][2][3][4][5][6]} Arnoux gagalı balinası, ilk olarak Georges Louis Duvernoy tarafından 1851 yılında Baird gagalı balinası ise 1883 yılında Leonhard Hess Stejneger tarafından tanımlanmıştır.^{[7][7][8][9][10][11]}

Özellikleri

Baird gagalı balinası ilüsttrasyonu.

Arnoux ve Baird gagalı balinası yaşadıkları yer ayrı olmasa denizde ayırt edilemeyecek kadar birbirine benzemektedir. Arnoux gagalı balinasının denizdeki tahmini boyu 12 metre olup ölü olarak görülenler ise 9,3 ile 9,75 metre arasındadır.^[12] Baird gagalı balinası ise görece daha büyük olup 12-13 metreye kadar büyüyebilmektedir. Her ikisinin de ağırlıkları 14 tona ulaşabilmektedir.

Her iki türün de gagaları diğer gagalı balinalara göre uzundur. Sırt yüzgeci vücudun arka tarafındadır. Vücut renkleri açık gri ile siyah arasında ve tüm vücutta aynı renktedir. Her iki tür de beyaz çizgisel izler olup yaşlandıkça büyümekte olup yağ belirlemede kullanılabilmektedir.

Üçüncü bir tür (henüz resmi olarak adlandırılmayan ancak Japonca karga anlamındaki Karasu olarak kullanılan) 2016 yılında tanımlanmıştır. Baird gagalı balinasına benzemesine rağmen mtDNA farklılığı vardır.^{[13][14][15][16][17]}

Popülasyon ve yayılım

Toplam popülasyon kesin olarak bilinmese de Baird gagalı balinasının 30.000 civarında olduğu tahmin edilmektedir. Üçüncü tür için herhangi bir bilgi yoktur.^[18]

Her iki türün de yayılımı antitropikal sulardır. Arnoux gagalı balinası Güney Afrika, Arjantin ve Yeni Zelanda'nın en güney uçları ile Antarktika arasında bulunur.^[19]

Baird gagalı balinası Büyük Okyanusun kuzeyinde özellikle Japonya adaları etrafında yaşamaktadır. En kuzey olarak Bering Denizi, en güney olarak Izu Adaları ve Bonin Adalarında kayıt edilmiştir. Çin'in Zhoushan sahillerinde kıyıya vurmalar da görülmüştür.^{[20][21][22][23][24]}

Yaşam şekli

Arnoux gagalı balinası

Bütün diğer gagalı balinagiller gibi onlar da büyük derinliklerde avladıkları kafadan bacaklılar ve krill ile beslenir.

Korunumu

1974 yılında avlanması yasaklanmadan önce 176 balina Sovyet avcılarınca yakalanmıştır. Amerikan ve Kanadalı avcılarca 1966'dan önce 60 ve Japon avcılarca 1986'dan önce 4000 civarında avlanamıştır.^{[25][26][27][28]}

Kaynakça

Konuyla ilgili yayınlar

• Giant Beaked Whales in the Encyclopedia of Marine Mammals pages 519-522 Teikyo Kasuya, 1998. ISBN 0-12-551340-2
• National Audubon Society Guide to Marine Mammals of the World Reeves et al., 2002. ISBN 0-375-41141-0.
• Whales, Dolphins and Porpoises Carwardine, 1995. ISBN 0-7513-2781-6
• An image of a Baird's Beaked Whale at monteraybaywhalewatch.com

Dış bağlantılar

• The Environmental Investigation Agency
• Whale & Dolphin Conservation Society (WDCS)
• Baird's Beaked Whale - ARKive bio
• Arnoux's Beaked Whale - ARKive bio
• Arnoux's beaked whale - The Beaked Whale Resource
• Baird's beaked whale - The Beaked Whale Resource
• Rare whale gathering sighted - BBC News
• Species Convention on Migratory species page on Baird's Beaked Whale
• Voices in the Sea - Sounds of the Baird's (Giant) beaked Whale

Berardius là một chi động vật có vú trong họ Ziphiidae, bộ Cetacea. Chi này được Duvernoy miêu tả năm 1851.^[1] Loài điển hình của chi này là Berardius arnuxii Duvernoy, 1851.

Các loài

Chi này gồm các loài:

Hình ảnh

Chú thích

Tham khảo

Bài viết liên quan đến Bộ Cá voi (Cetacea) này vẫn còn sơ khai. Bạn có thể giúp Wikipedia bằng cách mở rộng nội dung để bài được hoàn chỉnh hơn.

• x
• t
• s

Систематика
на Викивидах

Изображения
на Викискладе

Плавуны́^[1] (лат. Berardius) — род зубатых китов семейства клюворыловых. Включает два вида: северный плавун (Berardius bairdii) и южный плавун (Berardius arnuxii); которые, однако, столь близки, что иногда такое разделение считается ошибочным.^[2]

История изучения

Южного плавуна впервые описал Жорж Луи Дювернуа в 1851 году. Он дал название рода по фамилии французского адмирала Огюста Берара (фр. Auguste Berard), который был капитаном корвета, доставившего череп плавуна до Франции. Вид был назван в честь врача Мориса Арну (фр. Maurice Arnoux), нашедшего этот череп на побережье Южного острова Новой Зеландии.^[3] Северный плавун был описан Леонардом Штейнегером в 1883 году по черепу с 4 зубами, найденному им на острове Беринга. Этот вид был им назван в честь американского натуралиста Спенсера Фуллертона Бэрда.^[4]

Описание

Северные и южные плавуны практически неотличимы, единственное различие — это их ареал. Длина южных плавунов не превосходит 12 м, северных — может достигать 12—13 м. Вес достигает 14 тонн. Таким образом, плавуны — самые крупные представители семейства клюворылых китов.

Отличительной чертой является длинный клюв. Нижняя челюсть длиннее верхней. Окраска равномерная, от светло-серой до почти чёрной. Плавники небольшие, скруглённые. Половой диморфизм выражен слабо, самки несколько крупнее самцов.

С возрастом на теле плавунов остаются многочисленные белые шрамы.

Распространение

Области обитания двух видов не пересекаются. Северные плавуны встречаются в северной части Тихого океана, в Японском и южной части Охотского моря. Также они были обнаружены от Берингова моря до Калифорнийского полуострова и до южных островов Японии. Численность популяции оценивается в 30 000 китов.

Южные плавуны обитают в водах «Южного океана». Они встречаются у берегов Новой Зеландии, Аргентины, а также у Южной Георгии и Южной Африки. Самая северная граница, где они были зарегистрированы — 34 градуса южной широты.

Поведение

Жизнь плавунов изучена мало. Обычно они передвигаются в группах численностью от 3 до 10, а в редких случаях — до 50 особей. Интересным фактом является то, что 2/3 добытых китобоями плавунов — киты-самцы, несмотря на то, что китихи крупнее, поэтому являются более предпочтительной целью.

Статус популяции

Численность южных плавунов неизвестна, но, поскольку охота на них практически не ведётся, считается, что их вид не находится под угрозой. Северные плавуны в XX веке были объектами китобойного промысла. В конвенции о сохранении мигрирующих видов диких животных им присвоен неблагоприятный охранный статус.^[5]

Примечания

• ミナミツチクジラ Berardius arnuxii
  Duvernoy, 1851
• ツチクジラ Berardius bairdii
  Stejneger, 1883

ツチクジラ属（槌鯨属、Berardius）は、鯨偶蹄目ハクジラ亜目アカボウクジラ科に属する属の一つ。ミナミツチクジラとツチクジラの2種が属する。

ミナミツチクジラ（南槌鯨、Berardius arnuxii、フランス語: Bérardie d'Arnoux、英語: Arnoux's Beaked Whale）はツチクジラ属に属し、南半球に棲息する大型のクジラである。

ツチクジラ（槌鯨、Berardius bairdii、Baird's Beaked Whale）はツチクジラ属に属し、北半球に棲息する大型のクジラである。

ミナミツチクジラとツチクジラはアカボウクジラ科の中では一番大きいクジラであり、ハクジラ全体ではマッコウクジラに次ぐ大きさとなり、大きさもほぼ同じで、外観も非常に似通っている。

そのため、一部の動物学者は同一の種が変異して別々の種に分かれたという説を唱えている[McCann(1975)]。

ミナミツチクジラは、ニュージーランドで発見された頭蓋骨に基づき、1851年、Duvernoyによって新種として報告された。 属名の Berardius は、この頭蓋骨をニュージーランドからフランスに運んだ船の船長であるBerardに由来する。 種小名の arnuxii および英名のArnoux'sは同船の船医Arnouxに由来する[www.cetacea.org]。

ツチクジラは、ベーリング海で発見された試料に基づき、1883年、Stejnegerによって新種として報告された。 種小名の bairdii および英名のBaird'sは鳥類学者・魚類学者でありスミソニアン博物館の副館長も務めたBairdに由来する。

和名のツチ（槌）は、頭部の形状が稲藁を叩く槌に似ているからとされる。

分類[編集]

ツチクジラ属 Berardius

• ミナミツチクジラ Arnoux's Beaked Whale, Berardius arnuxii
• ツチクジラ Baird's Beaked Whale (North Pacific Bottlenose Whale), Berardius bairdii

身体[編集]

ミナミツチクジラとツチクジラの外観は非常によく似ている。 生息域が重なっていないため海上で識別する必要はないが、もしも生息域が重なっていたならば、識別は非常に困難になっていただろう。 身体の大きさは若干異なっており、ミナミツチクジラの方がツチクジラよりも少し小さい。 海上で観察された最も大きなミナミツチクジラの推定体長は12mであるが、標本として入手できているものはそれよりもかなり小さい。 一方、ツチクジラは成長すると12mから13m程度に達する。

両種とも、アカボウクジラ科の中でも比較的長い口吻を有する。 下顎が上顎よりも長く、口を閉じた状態でも下の前歯が見える。 頭部メロンは、アカボウクジラ科の中でも特に膨らんだ形状を持つ。 体型は細長く、胴回りは体長の50%程度に過ぎない。 体色はほぼ一色であり、個体による違いがあるが、明るい灰色から黒である。 胸びれは小さく、丸くなっている。 同じく背びれも小さく、丸くなっており、全長の3/4くらいの位置にある。 両種とも全身に白い引っかき傷がある。 この傷の個数は加齢とともに増えていくため、各個体の年齢の大雑把な見積もりに使用することができる。 また、両種とも性による外観の違いはほとんどない。

生息域、生息数[編集]

ミナミツチクジラとツチクジラの生息域は重なっておらず、完全に分かれている。

ミナミツチクジラは南極海に棲息する。 ニュージーランドやオーストラリアの海岸への座礁が少なくないことから、これらの国の南部海域から南極大陸までの海域においては、比較的一般に棲息しているものと考えられている。 サウスジョージア・サウスサンドウィッチ諸島や南アフリカ、ニュージーランドなどにも棲息しているため、南極海の広い海域に棲息していると考えられている。 また最北端の座礁の報告例は南緯34度であるため、極地に近い寒冷な海域だけではなく、温暖な海域にも棲息すると考えられる。

一方、ツチクジラは北太平洋、日本海、オホーツク海の南部などに棲息する。 大陸棚の端近くの沿岸側あたりを好むと考えられている。 北限はベーリング海、南限は東側はバハ・カリフォルニア半島、西側は小笠原諸島である。

ミナミツチクジラの全生息数は不明である。 ツチクジラの全生息数の見積もりは3万頭オーダーである。

生態[編集]

ミナミツチクジラの生態はほとんどわかっていないが、ツチクジラに似ているものと考えられている。

ツチクジラは、通常は3頭から10頭程度の群を成して行動するが、稀に50頭程度の群が観察される。 群の構成は良くわかっていない。 雌の方が雄よりも若干大きいので、捕獲の困難さに雌雄の差がないならば、雌の捕獲頭数の方が雄よりも多いことが予想されるのだが、実際には全捕獲頭数の2/3が雄であるため、調査捕鯨の結果からも群の構成は良くわかってはいない。

主な餌は魚類、頭足類などである。潜水深度は千メートル近くになり、深海性の大型のイカを捕食する事もある。

新種の可能性[編集]

近年、複数のストランディング個体の解剖や目撃情報等の資料が得られた結果、北海道沖（知床半島および網走沿岸）を含むオホーツク海にツチクジラの別種と思われる鯨類が生息する事が判明した^[1][2][3]。これらのクジラは既知のツチクジラ属よりもかなり小型で体長は6〜7mほど、黒味が強い体色などが特徴とされ、沿岸性であることが予想される^[4]。地元の捕鯨業者には代々「クロツチ」あるいは「カラス」と呼ばれていた。遺伝学的研究によると当種は既存のツチクジラ属2種とは異なる遺伝グループに属し、本種を加えるとツチクジラ属には3つの遺伝グループが存在することになる。 "キタトックリクジラ" は旧ソビエト連邦時代にオホーツク海で報告されており（キタトックリクジラは北大西洋にしか生息しない）^[5]、「上下の顎に4本の牙を持つツチクジラ」は、日本の伝統捕鯨で記録されていた^[6]。これらの記録が、存在が判明しつつある未知のツチクジラ属と関連しているかは不明である。

人間との関わり、保護[編集]

ミナミツチクジラは捕鯨の対象となったことはない。 不明な点もあるが、おそらく絶滅の惧れはあまりないものと考えられている。

一方、ツチクジラは、20世紀、主に日本によって捕鯨の対象になっていた。 日本は1986年の商業捕鯨モラトリアムまでに約4,000頭を捕獲した。 最も多いのは1952年の年間300頭であった。 ソ連、カナダ、アメリカも頭数は少ないが捕鯨を行っていた。 ソ連は1974年に捕鯨を中止するまでに176頭のツチクジラを、カナダ、アメリカは1966年に中止するまでに60頭のツチクジラをそれぞれ捕獲した。

現在日本は、自主規制による頭数制限（ツチクジラはIWCの管轄外）に従ってツチクジラを捕獲しており、その肉は日本の市場で流通しており、ミンククジラよりも多い。現在行われている程度の捕鯨頭数が種としての存続を脅かすことはないと考えられている。

千葉県、房総半島南部の特産品としてツチクジラの肉から作られる鯨のたれが有名である。

IUCNの2006年版レッドリストでは、両種とも「低リスク－保全対策依存」 (LRcd : Lower Risk - Conservation Dependent) に分類（1996年）されている。

近年、房総沖での発見・捕獲が困難になってきているとされるが、捕鯨の影響による個体群の減少なのか分布の変化なのかは不明とされる。同様に、浮島を始めとする東京湾では近年確認されている限りではストランディング個体のみのであり、相模湾や伊豆大島周辺でも確認が少なくなってきている。また、日本海では捕鯨の影響が暫く無かったため、人懐っこい個体が増えてきたとも言われるが、近年再開された捕鯨業が行動にどのような影響を及ぼすかは不明である。

食料として見た場合、ツチクジラの体内に含まれる微量の水銀に注意する必要がある。 厚生労働省は、ツチクジラを妊婦が摂食量を注意すべき魚介類の一つとして挙げており、2005年11月2日の発表では、1回に食べる量を約80gとした場合、ツチクジラの摂食は週に1回まで（１週間当たり80g程度）を目安としている^[7]。

日本のツチクジラ捕鯨の推移[編集]

木白による資料に基づく日本のツチクジラ捕鯨の推移である。

• 17世紀頃 - 明治初頭 － 手投げ銛による小規模な捕鯨
• 第二次世界大戦後 － 小型捕鯨船による商業捕鯨活発（最も多い時で1952年の年間300頭以上）
• 1983年 - 年間40頭までに自主規制
• 1990年 - 年間54頭までに自主規制
• 1999年 - 別途日本海における捕獲頭数を年間8頭までに自主規制（合計62頭）

参考文献[編集]

1. ^ 北村志乃,2013, DNAで未知の鯨種に挑む－日本近海のツチクジラについて－,セトケンニューズレター32号, retrived on 26,January,2014
2. ^ 羅臼の海大集合！,19,Aug,2013, 知床ネイチャークルーズ　ニュース,http://e-shiretoko.sblo.jp/article/72812806.html, retrived on 26,January,2014
3. ^ 宇仁義和, 小山香菜, 中郡翔太郎, 前田光彦. 2014[1] 知床博物館研究報告 第36集 29–40. 2014年5月30日閲覧
4. ^ https://twitter.com/UNI_Yoshikazu/status/221551951811313664
5. ^ 宇仁義和,2006, 知床周辺海域の鯨類, 知床博物館研究報告 27: 37-46 (2006), retrived on 26,January,2014
6. ^ 粕谷俊雄, 2011, イルカ―小型鯨類の保全生物学, 東京大学出版会, retrived on 26,January,2014
7. ^ 厚生労働省医薬食品局食品安全部基準審査課 (妊婦への魚介類の摂食と水銀に関する注意事項の見直しについて(Q&A)（平成17年11月2日）”. 魚介類に含まれる水銀について. 厚生労働省. オリジナルよりアーカイブ。ISBN 0125513402
8. Reeves et al., National Audubon Society Guide to Marine Mammals of the World (2002). ISBN 0375411410.
9. Carwardine, Whales, Dolphins and Porpoises (1995). ISBN 0751327816
10. McCann, "A study of the genus Berardius," Sci. Rep. Whales Res. Inst., Vol. 27, pp. 111-137 (1975).
11. www.monteraybaywhalewatch.com ツチクジラの写真（英文）
12. www.cetacean.org 学名・英名の由来（英文、リンク切れ）
13. 木白、"ツチクジラ" 日本の捕獲頭数
14. 海棲哺乳類図鑑「ミナミツチクジラ」 国立科学博物館 動物研究部
15. 海棲哺乳類図鑑「ツチクジラ」 国立科学博物館 動物研究部

この項目は、動物に関連した書きかけの項目です。この項目を加筆・訂正などしてくださる協力者を求めています（Portal:生き物と自然／プロジェクト:生物）。

부리고래속(Berardius)은 부리고래과에 속하는 고래 속의 하나이다.^[1] 남반구에 서식하는 아르누부리고래와 북반구에 사는 망치고래의 2종으로 이루어져 있다. 이 2종은 부리고래과 고래 중에서 가장 크며, 이빨고래 전체에서는 향고래 다음으로 크기도 비슷하고, 겉모습도 매우 비슷하다. 그래서 일부 동물학자는 같은 종이 변이를 일으켜 다른 종으로 갈라졌다는 설을 주장하고 있다.^[2]

하위 종

• 아르누부리고래 (Berardius arnuxii)
• 큰부리고래 또는 망치고래 (Berardius bairdii)

각주