The Ross seal (Ommatophoca rossii) is a true seal (family Phocidae) with a range confined entirely to the pack ice of Antarctica. It is the only species of the genus Ommatophoca. First described during the Ross expedition in 1841, it is the smallest, least abundant and least well known of the Antarctic pinnipeds. Its distinctive features include disproportionately large eyes, whence its scientific name (Ommato- meaning "eye", and phoca meaning "seal"), and complex, trilling and siren-like vocalizations. Ross seals are brachycephalic, as they have a short broad muzzle and have the shortest fur of any other seal.
The Ross seal shares a recent common ancestor with three other extant Antarctic seals, which are together known as the lobodontine seals. The other species are the crabeater seal (Lobodon carcinophaga), leopard seal (Hydrurga leptonyx) and Weddell seal (Leptonychotes weddelli).[2] These species, collectively belonging to the seal tribe Lobodontini, share teeth adaptations, including lobes and cusps useful for straining smaller prey items out of the water column. The ancestral Lobodontini likely diverged from its sister clade, Mirounga (elephant seals) in the late Miocene to early Pliocene, when they migrated southward and diversified rapidly in relative isolation around Antarctica.[2] However, the only fossils of Ross seals so far known date from much later, during the early Pleistocene of New Zealand.[3]
Description
Ross seals reach a length of about 1.68–2.09 m (5.5–6.9 ft) and weight of 129–216 kg (284–476 lb); females are slightly larger at 1.96–2.5 m (6.4–8.2 ft).[1] A molecular genetic based technique has been established to confirm the sex of individuals in the laboratory.[4] Pups are about 1 m and 16 kg at birth. The coat is colored dark-brown in the dorsal area and silvery-white beneath. At the onset of the Antarctic winter, the coat fades gradually to become light brown. At close range, the Ross seal can be easily identified by its large eyes, which are up to 7 cm in diameter.
The Ross seal is able to produce a variety of complex twittering and siren-like sounds that are performed on ice and underwater, where they carry for long distances.[5] The underwater siren sound can be composed of two harmonically unrelated superimposed tones that are pulsed with the same rhythm. Uniquely, the vocalizations, whether on ice or in water, are made with a closed mouth - emitting no air. The purpose of these sounds is unknown, though their distinctive nature and long range are likely to facilitate either encounters or avoidance of individuals.[5]
Range and population status
Although its close relatives Weddell seals, crabeater seals and leopard seals are ubiquitous in Antarctic waters, the Ross seal is an uncommon and relatively unknown animal, considered to be the least common pack ice seal. It almost never leaves the Antarctic Ocean, with the very rare exception of stray animals found around subantarctic islands, and uniquely, off the south coast of Australia. Nonetheless, its distribution is circumpolar, with individuals found in low densities - usually singly - in very thick pack ice in all regions of the continent.
The total Ross seal population is estimated at around 130,000 individuals, but there is great uncertainty in this estimate (reported 95% confidence intervals range from 20,000 to 227,000).[6] Thus, very little is known about trends in the population. A genetic survey did not detect evidence of a recent, sustained genetic bottleneck in this species,[7] which suggests that populations do not appear to have suffered a detectable and sustained decline in the recent past.
Interactions with humans have been limited. They have been collected historically by Antarctic expeditions and for scientific collections. Their range does not generally overlap with commercial fishing.
Feeding and reproductive behavior
Ross seal feeds primarily on squid and fish, primarily Antarctic silverfish, in the pelagic zone.[8] Ross seals are presumed to be preyed upon by killer whales (Orcinus orca) and leopard seals, large predators that share their Antarctic habitat, though there are no documented observations of predation.
Females give birth to their young on the ice in November. Pups are nursed for only four weeks before weaning. Mating is thought to occur underwater shortly after the pup is weaned, but has never been observed. Ross seals mature sexually at approximately three years of age, and are thought to live around 20 years in the wild.[8]
^ abHückstädt, L. (2015). "Ommatophoca rossii". IUCN Red List of Threatened Species. 2015: e.T15269A45228952. doi:10.2305/IUCN.UK.2015-4.RLTS.T15269A45228952.en. Retrieved 12 November 2021.
^ abFyler, C. A.; Reeder, T.W.; Berta, A.; Antonelis, G.; Aguilar, A.; Androukaki, E. (2005), "Historical biogeography and phylogeny of monachine seals (Pinnipedia: Phocidae) based on mitochondrial and nuclear DNA data", Journal of Biogeography, 32 (7): 1267–1279, doi:10.1111/j.1365-2699.2005.01281.x, S2CID 15187438
^Berta, A.; Churchill, M. (2012). "Pinniped Taxonomy: evidence for species and subspecies". Mammal Review. 42 (3): 207–234. doi:10.1111/j.1365-2907.2011.00193.x.
^Curtis, Caitlin; Stewart, Brent S.; Karl, Stephen A. (2007-05-01). "Sexing Pinnipeds with ZFX and ZFY Loci". Journal of Heredity. 98 (3): 280–285. doi:10.1093/jhered/esm023. ISSN 0022-1503. PMID 17548861.
^ abWatkins, William A.; Carleton Ray, G. (1985), "In-air and underwater sounds of the Ross seal, Ommatophoca rossi", The Journal of the Acoustical Society of America, 77 (4): 1598–1600, Bibcode:1985ASAJ...77.1598W, doi:10.1121/1.392003, retrieved 2010-06-06
^Southwell, C.J.; Paxton, C.G.M.; Borchers, D.L.; Boveng, P.L.; Nordøy, E.S.; Blix, A.S.; De La Mare, W.K. (2008), "Estimating population status under conditions of uncertainty: the Ross seal in East Antarctica", Antarctic Science, 20 (2): 123–133, Bibcode:2008AntSc..20..123S, doi:10.1017/s0954102007000879, S2CID 130100515
^Curtis, Caitlin; Stewart, Brent S.; Karl, Stephen A. (2011-07-07). "Genetically effective population sizes of Antarctic seals estimated from nuclear genes". Conservation Genetics. 12 (6): 1435–1446. doi:10.1007/s10592-011-0241-x. ISSN 1566-0621. S2CID 732351.
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ross, seal, ommatophoca, rossii, true, seal, family, phocidae, with, range, confined, entirely, pack, antarctica, only, species, genus, ommatophoca, first, described, during, ross, expedition, 1841, smallest, least, abundant, least, well, known, antarctic, pin. The Ross seal Ommatophoca rossii is a true seal family Phocidae with a range confined entirely to the pack ice of Antarctica It is the only species of the genus Ommatophoca First described during the Ross expedition in 1841 it is the smallest least abundant and least well known of the Antarctic pinnipeds Its distinctive features include disproportionately large eyes whence its scientific name Ommato meaning eye and phoca meaning seal and complex trilling and siren like vocalizations Ross seals are brachycephalic as they have a short broad muzzle and have the shortest fur of any other seal Ross sealConservation statusLeast Concern IUCN 3 1 1 Scientific classificationKingdom AnimaliaPhylum ChordataClass MammaliaOrder CarnivoraClade PinnipediaFamily PhocidaeGenus OmmatophocaGray 1844Species O rossiiBinomial nameOmmatophoca rossii Gray 1844 Ross seal range Contents 1 Taxonomy and evolution 2 Description 3 Range and population status 4 Feeding and reproductive behavior 5 See also 6 References 7 External linksTaxonomy and evolution EditThe Ross seal shares a recent common ancestor with three other extant Antarctic seals which are together known as the lobodontine seals The other species are the crabeater seal Lobodon carcinophaga leopard seal Hydrurga leptonyx and Weddell seal Leptonychotes weddelli 2 These species collectively belonging to the seal tribe Lobodontini share teeth adaptations including lobes and cusps useful for straining smaller prey items out of the water column The ancestral Lobodontini likely diverged from its sister clade Mirounga elephant seals in the late Miocene to early Pliocene when they migrated southward and diversified rapidly in relative isolation around Antarctica 2 However the only fossils of Ross seals so far known date from much later during the early Pleistocene of New Zealand 3 Description EditRoss seals reach a length of about 1 68 2 09 m 5 5 6 9 ft and weight of 129 216 kg 284 476 lb females are slightly larger at 1 96 2 5 m 6 4 8 2 ft 1 A molecular genetic based technique has been established to confirm the sex of individuals in the laboratory 4 Pups are about 1 m and 16 kg at birth The coat is colored dark brown in the dorsal area and silvery white beneath At the onset of the Antarctic winter the coat fades gradually to become light brown At close range the Ross seal can be easily identified by its large eyes which are up to 7 cm in diameter The Ross seal is able to produce a variety of complex twittering and siren like sounds that are performed on ice and underwater where they carry for long distances 5 The underwater siren sound can be composed of two harmonically unrelated superimposed tones that are pulsed with the same rhythm Uniquely the vocalizations whether on ice or in water are made with a closed mouth emitting no air The purpose of these sounds is unknown though their distinctive nature and long range are likely to facilitate either encounters or avoidance of individuals 5 Range and population status EditAlthough its close relatives Weddell seals crabeater seals and leopard seals are ubiquitous in Antarctic waters the Ross seal is an uncommon and relatively unknown animal considered to be the least common pack ice seal It almost never leaves the Antarctic Ocean with the very rare exception of stray animals found around subantarctic islands and uniquely off the south coast of Australia Nonetheless its distribution is circumpolar with individuals found in low densities usually singly in very thick pack ice in all regions of the continent The total Ross seal population is estimated at around 130 000 individuals but there is great uncertainty in this estimate reported 95 confidence intervals range from 20 000 to 227 000 6 Thus very little is known about trends in the population A genetic survey did not detect evidence of a recent sustained genetic bottleneck in this species 7 which suggests that populations do not appear to have suffered a detectable and sustained decline in the recent past Interactions with humans have been limited They have been collected historically by Antarctic expeditions and for scientific collections Their range does not generally overlap with commercial fishing Feeding and reproductive behavior EditRoss seal feeds primarily on squid and fish primarily Antarctic silverfish in the pelagic zone 8 Ross seals are presumed to be preyed upon by killer whales Orcinus orca and leopard seals large predators that share their Antarctic habitat though there are no documented observations of predation Females give birth to their young on the ice in November Pups are nursed for only four weeks before weaning Mating is thought to occur underwater shortly after the pup is weaned but has never been observed Ross seals mature sexually at approximately three years of age and are thought to live around 20 years in the wild 8 See also EditPortals Marine life MammalsReferences Edit a b Huckstadt L 2015 Ommatophoca rossii IUCN Red List of Threatened Species 2015 e T15269A45228952 doi 10 2305 IUCN UK 2015 4 RLTS T15269A45228952 en Retrieved 12 November 2021 a b Fyler C A Reeder T W Berta A Antonelis G Aguilar A Androukaki E 2005 Historical biogeography and phylogeny of monachine seals Pinnipedia Phocidae based on mitochondrial and nuclear DNA data Journal of Biogeography 32 7 1267 1279 doi 10 1111 j 1365 2699 2005 01281 x S2CID 15187438 Berta A Churchill M 2012 Pinniped Taxonomy evidence for species and subspecies Mammal Review 42 3 207 234 doi 10 1111 j 1365 2907 2011 00193 x Curtis Caitlin Stewart Brent S Karl Stephen A 2007 05 01 Sexing Pinnipeds with ZFX and ZFY Loci Journal of Heredity 98 3 280 285 doi 10 1093 jhered esm023 ISSN 0022 1503 PMID 17548861 a b Watkins William A Carleton Ray G 1985 In air and underwater sounds of the Ross seal Ommatophoca rossi The Journal of the Acoustical Society of America 77 4 1598 1600 Bibcode 1985ASAJ 77 1598W doi 10 1121 1 392003 retrieved 2010 06 06 Southwell C J Paxton C G M Borchers D L Boveng P L Nordoy E S Blix A S De La Mare W K 2008 Estimating population status under conditions of uncertainty the Ross seal in East Antarctica Antarctic Science 20 2 123 133 Bibcode 2008AntSc 20 123S doi 10 1017 s0954102007000879 S2CID 130100515 Curtis Caitlin Stewart Brent S Karl Stephen A 2011 07 07 Genetically effective population sizes of Antarctic seals estimated from nuclear genes Conservation Genetics 12 6 1435 1446 doi 10 1007 s10592 011 0241 x ISSN 1566 0621 S2CID 732351 a b Skinner J D Klages NTW 1994 On some aspects of the biology of the Ross seal Ommatophoca rossii from King Haakon VII Sea Antarctica Polar Biology 14 7 472 doi 10 1007 bf00239051 S2CID 28880147External links Edit Wikimedia Commons has media related to Ommatophoca rossii University of Michigan museum of zoology Seal conservation society webpage Fisheries Global Information System factsheet Retrieved from https en wikipedia org w index php title Ross seal amp oldid 1115454634, wikipedia, wiki, book, books, library,
