The strap-toothed beaked whale (Mesoplodon layardii), also known as Layard's beaked whale, is one of the largest members of the mesoplodont genus, growing to 6.2 m (20 ft) in length and reaching up to 1,300 kg (2,900 lb).[3] The common and scientific name was given in honor of Edgar Leopold Layard, the curator of the South African Museum, who prepared drawings of a skull and sent them to the British taxonomist John Edward Gray, who described the species in 1865.[4]
Strap-toothed beaked whale
A porpoising strap-toothed whale, photographed in the Drake Passage between Chile and Antarctica
Adult strap-toothed beaked whales show a distinctive colouration that perhaps makes them one of the most readily distinguishable beaked whale species. Adults have a white beak, with a pale white 'cape' that extends to halfway between the dorsal fin and head. The dorsal fin is set far back down the body and is white-tipped. The flukes also have white tips. When observed closely, either at sea or when stranded, these whales show a pale neckband that separates the darker grey colouration found upon the head and melon from the rest of the body. While adult whales show striking colouration, juvenile animals are harder to distinguish from other beaked whale species, having a uniform grey colouration.[5] Males can reach around 5.9 metres (19 ft), whereas females reach 6.2 metres (20 ft) and likely weigh around 1,000–1,300 kilograms (2,200–2,900 lb). Newborn calves may be up to 2.8 metres (9.2 ft) in length.[4]
Beaked whales show remarkable sexual dimorphism in that only the males retain functional teeth. Male strap-toothed beaked whales begin to develop a large flat tusk from each lower jaw as juveniles, growing at a 45° angle back towards the head and over the rostrum (beak). Reaching up to 34 cm in length,[6] the teeth may overlap at the tips, restricting the gape size of the animal. Two stranded adult male strap-toothed beaked whales were recorded as only being able to open their mouths 3.2 cm and 4 cm wide, compared to females and juveniles that had a gape size of 6.5 cm.[7] It is thought male beaked whales use their teeth to compete for mating access to females, as evidenced by scars and scratches on the bodies of males. However it is unlikely the whale uses the whole tusk for such aggressive interactions, instead, it is probable that only a small denticle found upon the upper surface of the tooth is utilised.[8]
Small denticles on the upper surface of the male's tusks
Geographical range/ distributionEdit
Based on sporadic sightings and a number of stranded animals, it appears that the Strap-toothed beaked whale ranges widely across the Southern Ocean, with a possible circumpolar distribution in sub-Antarctic and temperate waters. Records for the species have been made in Tierra del Fuego and Chubut in Argentina, the Falkland Islands, Western and Southern Australia and New Zealand.[9]
The northernmost extent of the range is continually changing; strandings were noted at 31–32° south of the equator along Brazil's southern coast [10] until an emaciated individual was found at 13° S on Maré Island off the north-east coast of Brazil in 2002.[11] However, in 2011 an adult male strap-toothed beaked whale stranded alive in Myanmar at 16° north of the equator; more than 5000 km further north than the previously accepted range of the species. The whale died and a necropsy revealed that there was no prey within the stomach, but the overall body condition was good.[12]
It is possible that this species migrates due to the seasonality of observed strandings.[13][14]
BehaviourEdit
Little is known about the behaviour of this species. Beaked whales are thought to travel in small groups, and observed group sizes for the strap-toothed beaked whale range from two to ten individuals.[15][5] Social structure of Mesoplodonts in general is largely understudied, due to the difficulty of observing individuals at sea. It is possible that group sizes and composition are controlled by the type of rostrum and teeth found amongst the various species. Larger and heavily armed species that can inflict wounds generally travel in groups where only one or two males are present, reducing the risk of aggressive interactions.[16][5] Despite having large tusks, male strap-toothed beaked whales likely only use a small protruding denticle on each tooth in antagonistic interactions. Subsequently, this species may travel in groups with multiple males as the risk of serious injury is lessened.[5]
The species is reported to bask at the water's surface on calm days, but is noted to be difficult to approach in vessels. Strap-toothed beaked whales typically do not show their flukes upon diving. A number of observations suggest that diving is typified by a slow descent beneath the surface,[17] with dive duration lasting between 10 and 15 minutes.[18] The species can travel at speed, and may show 'porpoising' behaviour.
The killer whale (Orcinus orca) is a documented predator of this species, and has been recorded chasing, attacking and killing a solitary adult strap-toothed whale approximately 50 km offshore of Bremer Bay in south-western Australia.[19]
The main prey of the strap-tooth beaked whale is considered to be oceanic squid species. In an extensive dietary analysis of 14 stranded whales from New Zealand and South Africa, 94.8% of the stomach contents were composed of cephalopods, with evidence of some fish and crustaceans.[20] A difference in the shape of consumed prey was noted between male and female whales, but it was determined that both sexes targeted squid of a similar size. While adult males have a restricted gape size due to the position of their overlapping tusks, it is possible that this allows them to create more suction when feeding, allowing them to forage effectively on the same prey as females and juveniles.
Population statusEdit
A strap-tooth beaked whale is seen porpoising through the water as a killer whale attacks its right flank, resulting in a large bite wound
The size of the population is unknown, however it has been noted that the species is one of the more common beaked whale species found in the southern ocean.[21][22]
ThreatsEdit
Strap-toothed beaked whales have not been commercially hunted; however, they are at risk from entanglement and disturbance from anthropogenic noise. Intense noise, particularly that from sonar, has been shown to cause panic, rapid ascent and subsequent death due to decompression sickness in a number of beaked whale species.[23][24]
As the species has a largely circumpolar distribution, it is likely to be at risk from the impacts of anthropogenic climate change. The International Union for the Conservation of Nature (IUCN) lists habitat alteration and habitat shift as possible threats related to climate change.[13]
^Jefferson, Thomas; Webber, Marc A.; Pitman, Robert L. (2008). Marine Mammals of the World: A Comprehensive Guide to their Identification. London: Academic.
^ abReeves, R.; Stewart, B.; Clapham, P. & Powell, J. (2002). Guide to Marine Mammals of the World. New York: A.A. Knopf. p. 292. ISBN978-0-375-41141-0.
^ abcdPitman, RL; Totterdell, J; Wellard, R; Cullen, P; De Boer, M (2019). "Long in the tooth: Biological observations from at-sea sightings of strap-toothed beaked whales (Mesoplodon layardii)". Marine Mammal Science. 35 (3): 1141–1161. doi:10.1111/mms.12575. S2CID 91325604.
^Best, P (2007). Whales and dolphins of the southern African subregion. Cambridge: Cambridge University Press.
^Sekiguchi, K (July 1996). "The diet of strap-toothed whales (Mesoplodon layardii)". Journal of Zoology. 239 (3): 453–463. doi:10.1111/j.1469-7998.1996.tb05935.x.
^Best, P (2007). Whales and dolphins of the southern African subregion. Cambridge: Cambridge University Press.
^Rice, DW (1998). Wartzok, D (ed.). "Marine Mammals of the World: systematics and distribution" (PDF) (Society for Marine Mammalogy,Special Publication No. 4). Lawrence, KS: Allen Press, Inc. {{cite journal}}: Cite journal requires |journal= (help)
^Pinedo, MC; Barreto, AS; Lammardo, MP; Andrade, ALV; Geracitano, L (2002). "Northernmost records of the spectacled porpoise, Layard's beaked whale, Commerson's dolphin and Peale's dolphin in the southwestern Atlantic Ocean". Aquatic Mammals. 28 (1): 32–37.
^Maia-Nogueira, R; Nunes, JAC (2005). "Record of Layard's beaked whale, Mesoplodon layardii (Gray,1856), in northeastern Brazil". Latin American Journal of Aquatic Mammals. 4 (2): 137–139. doi:10.5597/lajam00082.
^Chit, AM; Smith, BD; Tun, MT (2012). "An extreme extra-limital record of a strap-toothed beaked whale (Mesoplodon layardii)". Marine Biodiversity Records. 5 (e5): 1–3. doi:10.1017/S1755267211001060.
^ abTaylor, B.L.; Baird, R.; Barlow, J.; Dawson, S.M.; Ford, J.; Mead, J.G.; Notarbartolo di Sciara, G.; Wade, P. & Pitman, R.L. (2008). "Mesoplodon layardii". IUCN Red List of Threatened Species. 2008: e.T13249A3429897. doi:10.2305/IUCN.UK.2008.RLTS.T13249A3429897.en.
^Pitman, R (2009). "Mesoplodont whales". In Perrin, WF; Würsig, B; Thewissen, JGM (eds.). Encyclopedia of marine mammals, 2nd Ed. Academic Press. pp. 721–726. ISBN9780128043813.
^Best, P (2007). Whales and dolphins of the southern African subregion. Cambridge: Cambridge University Press.
^Heyning, JE (1984). "Functional morphology involved in intraspecific fighting of the beaked whale, Mesoplodon carlhubbsi". Canadian Journal of Zoology. 62 (8): 1645–1654. doi:10.1139/z84-239.
^Culik, B (2011). Perrin (ed.). Odontocetes- The Toothed Whales-CMS Technical Series No.24. Joint Secretariat of the Convention of Migratory Species of Wild Animals and the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas (UNEP/CMS/ASCOBANS). ISBN978-3-937429-92-2.
^Carwardine, M (1995). Whales, Dolphins and Porpoises. London: Darling Kindersley.
^Wellard, R; Lightbody, K; Fouda, L; Blewitt, M; Riggs, D; Erbe, C (2016). "Killer whale (Mesoplodon layardii) Predation on Beaked Whales (Mesoplodon spp.) in the Bremer sub-basin, Western Australia". PLOS ONE. 11 (12): e0166670. doi:10.1371/journal.pone.0166670. PMC5140045. PMID 27923044.
^Sekiguchi, K (July 1996). "The diet of strap-toothed whales (Mesoplodon layardii)". Journal of Zoology. 239 (3): 453–463. doi:10.1111/j.1469-7998.1996.tb05935.x.
^Pitman, R (2002). "Mesoplodont whales". In Perrin, WF; Wursig, B; Thewissen, JGM (eds.). Encyclopedia of marine mammals, 1st Ed. Academic Press. pp. 738–742.
^Pitman, R (2009). "Mesoplodont whales". In Perrin, WF; Wursig, B; Thewissen, JGM (eds.). Encyclopedia of marine mammals, 2nd Ed. Academic Press. pp. 721–726. ISBN9780128043813.
^Rommel, SA; Costidis, AM; Fernández, A; Jepson, PD; Pabst, DA; McLellan, WA; Houser, DS; Cranford, TW; van Helden, AL; Allan, DM; Barros, NB (2006). "Elements of beaked whale anatomy and diving physiology and some hypothetical causes of sonar-related stranding". Journal of Cetacean Research and Management. 7 (3): 189–209. doi:10.1111/mms.12575. S2CID 91325604.
^Filadelfo, R; Mintz, J; Michlovich, E; D’Amico, A; Tyack, PL; Ketten (2009). "Correlating Military Sonar Use with Beaked Whale Mass Strandings: What Do the Historical Data Show?". Aquatic Mammals. 35 (4): 435–444. doi:10.1578/AM.35.4.2009.435.
Encyclopedia of Marine Mammals. Edited by William F. Perrin, Bernd Wursig, and J.G.M Thewissen. Academic Press, 2002. ISBN0-12-551340-2
External linksEdit
Wikimedia Commons has media related to Mesoplodon layardii.
strap, toothed, whale, strap, toothed, beaked, whale, mesoplodon, layardii, also, known, layard, beaked, whale, largest, members, mesoplodont, genus, growing, length, reaching, common, scientific, name, given, honor, edgar, leopold, layard, curator, south, afr. The strap toothed beaked whale Mesoplodon layardii also known as Layard s beaked whale is one of the largest members of the mesoplodont genus growing to 6 2 m 20 ft in length and reaching up to 1 300 kg 2 900 lb 3 The common and scientific name was given in honor of Edgar Leopold Layard the curator of the South African Museum who prepared drawings of a skull and sent them to the British taxonomist John Edward Gray who described the species in 1865 4 Strap toothed beaked whaleA porpoising strap toothed whale photographed in the Drake Passage between Chile and AntarcticaSize compared to an average humanConservation statusLeast Concern IUCN 3 1 1 CITES Appendix II CITES 2 Scientific classificationDomain EukaryotaKingdom AnimaliaPhylum ChordataClass MammaliaOrder ArtiodactylaInfraorder CetaceaFamily ZiphiidaeGenus MesoplodonSpecies M layardiiBinomial nameMesoplodon layardii Gray 1865 Strap toothed whale range Contents 1 Description 2 Geographical range distribution 3 Behaviour 4 Population status 5 Threats 6 See also 7 References 8 External linksDescription Edit Skull of a male strap toothed beaked whaleAdult strap toothed beaked whales show a distinctive colouration that perhaps makes them one of the most readily distinguishable beaked whale species Adults have a white beak with a pale white cape that extends to halfway between the dorsal fin and head The dorsal fin is set far back down the body and is white tipped The flukes also have white tips When observed closely either at sea or when stranded these whales show a pale neckband that separates the darker grey colouration found upon the head and melon from the rest of the body While adult whales show striking colouration juvenile animals are harder to distinguish from other beaked whale species having a uniform grey colouration 5 Males can reach around 5 9 metres 19 ft whereas females reach 6 2 metres 20 ft and likely weigh around 1 000 1 300 kilograms 2 200 2 900 lb Newborn calves may be up to 2 8 metres 9 2 ft in length 4 Beaked whales show remarkable sexual dimorphism in that only the males retain functional teeth Male strap toothed beaked whales begin to develop a large flat tusk from each lower jaw as juveniles growing at a 45 angle back towards the head and over the rostrum beak Reaching up to 34 cm in length 6 the teeth may overlap at the tips restricting the gape size of the animal Two stranded adult male strap toothed beaked whales were recorded as only being able to open their mouths 3 2 cm and 4 cm wide compared to females and juveniles that had a gape size of 6 5 cm 7 It is thought male beaked whales use their teeth to compete for mating access to females as evidenced by scars and scratches on the bodies of males However it is unlikely the whale uses the whole tusk for such aggressive interactions instead it is probable that only a small denticle found upon the upper surface of the tooth is utilised 8 Small denticles on the upper surface of the male s tusksGeographical range distribution EditBased on sporadic sightings and a number of stranded animals it appears that the Strap toothed beaked whale ranges widely across the Southern Ocean with a possible circumpolar distribution in sub Antarctic and temperate waters Records for the species have been made in Tierra del Fuego and Chubut in Argentina the Falkland Islands Western and Southern Australia and New Zealand 9 The northernmost extent of the range is continually changing strandings were noted at 31 32 south of the equator along Brazil s southern coast 10 until an emaciated individual was found at 13 S on Mare Island off the north east coast of Brazil in 2002 11 However in 2011 an adult male strap toothed beaked whale stranded alive in Myanmar at 16 north of the equator more than 5000 km further north than the previously accepted range of the species The whale died and a necropsy revealed that there was no prey within the stomach but the overall body condition was good 12 It is possible that this species migrates due to the seasonality of observed strandings 13 14 Behaviour EditLittle is known about the behaviour of this species Beaked whales are thought to travel in small groups and observed group sizes for the strap toothed beaked whale range from two to ten individuals 15 5 Social structure of Mesoplodonts in general is largely understudied due to the difficulty of observing individuals at sea It is possible that group sizes and composition are controlled by the type of rostrum and teeth found amongst the various species Larger and heavily armed species that can inflict wounds generally travel in groups where only one or two males are present reducing the risk of aggressive interactions 16 5 Despite having large tusks male strap toothed beaked whales likely only use a small protruding denticle on each tooth in antagonistic interactions Subsequently this species may travel in groups with multiple males as the risk of serious injury is lessened 5 The species is reported to bask at the water s surface on calm days but is noted to be difficult to approach in vessels Strap toothed beaked whales typically do not show their flukes upon diving A number of observations suggest that diving is typified by a slow descent beneath the surface 17 with dive duration lasting between 10 and 15 minutes 18 The species can travel at speed and may show porpoising behaviour The killer whale Orcinus orca is a documented predator of this species and has been recorded chasing attacking and killing a solitary adult strap toothed whale approximately 50 km offshore of Bremer Bay in south western Australia 19 The main prey of the strap tooth beaked whale is considered to be oceanic squid species In an extensive dietary analysis of 14 stranded whales from New Zealand and South Africa 94 8 of the stomach contents were composed of cephalopods with evidence of some fish and crustaceans 20 A difference in the shape of consumed prey was noted between male and female whales but it was determined that both sexes targeted squid of a similar size While adult males have a restricted gape size due to the position of their overlapping tusks it is possible that this allows them to create more suction when feeding allowing them to forage effectively on the same prey as females and juveniles Population status Edit A strap tooth beaked whale is seen porpoising through the water as a killer whale attacks its right flank resulting in a large bite woundThe size of the population is unknown however it has been noted that the species is one of the more common beaked whale species found in the southern ocean 21 22 Threats EditStrap toothed beaked whales have not been commercially hunted however they are at risk from entanglement and disturbance from anthropogenic noise Intense noise particularly that from sonar has been shown to cause panic rapid ascent and subsequent death due to decompression sickness in a number of beaked whale species 23 24 As the species has a largely circumpolar distribution it is likely to be at risk from the impacts of anthropogenic climate change The International Union for the Conservation of Nature IUCN lists habitat alteration and habitat shift as possible threats related to climate change 13 See also Edit Cetaceans portal Mammals portal Marine life portalList of cetaceansReferences Edit Pitman R L Brownell Jr R L 2020 Mesoplodon layardii IUCN Red List of Threatened Species 2020 e T13249A50366790 doi 10 2305 IUCN UK 2020 3 RLTS T13249A50366790 en Retrieved 19 November 2021 Appendices CITES cites org Retrieved 2022 01 14 Jefferson Thomas Webber Marc A Pitman Robert L 2008 Marine Mammals of the World A Comprehensive Guide to their Identification London Academic a b Reeves R Stewart B Clapham P amp Powell J 2002 Guide to Marine Mammals of the World New York A A Knopf p 292 ISBN 978 0 375 41141 0 a b c d Pitman RL Totterdell J Wellard R Cullen P De Boer M 2019 Long in the tooth Biological observations from at sea sightings of strap toothed beaked whales Mesoplodon layardii Marine Mammal Science 35 3 1141 1161 doi 10 1111 mms 12575 S2CID 91325604 Best P 2007 Whales and dolphins of the southern African subregion Cambridge Cambridge University Press Sekiguchi K July 1996 The diet of strap toothed whales Mesoplodon layardii Journal of Zoology 239 3 453 463 doi 10 1111 j 1469 7998 1996 tb05935 x Best P 2007 Whales and dolphins of the southern African subregion Cambridge Cambridge University Press Rice DW 1998 Wartzok D ed Marine Mammals of the World systematics and distribution PDF Society for Marine Mammalogy Special Publication No 4 Lawrence KS Allen Press Inc a href Template Cite journal html title Template Cite journal cite journal a Cite journal requires journal help Pinedo MC Barreto AS Lammardo MP Andrade ALV Geracitano L 2002 Northernmost records of the spectacled porpoise Layard s beaked whale Commerson s dolphin and Peale s dolphin in the southwestern Atlantic Ocean Aquatic Mammals 28 1 32 37 Maia Nogueira R Nunes JAC 2005 Record of Layard s beaked whale Mesoplodon layardii Gray 1856 in northeastern Brazil Latin American Journal of Aquatic Mammals 4 2 137 139 doi 10 5597 lajam00082 Chit AM Smith BD Tun MT 2012 An extreme extra limital record of a strap toothed beaked whale Mesoplodon layardii Marine Biodiversity Records 5 e5 1 3 doi 10 1017 S1755267211001060 a b Taylor B L Baird R Barlow J Dawson S M Ford J Mead J G Notarbartolo di Sciara G Wade P amp Pitman R L 2008 Mesoplodon layardii IUCN Red List of Threatened Species 2008 e T13249A3429897 doi 10 2305 IUCN UK 2008 RLTS T13249A3429897 en Pitman R 2009 Mesoplodont whales In Perrin WF Wursig B Thewissen JGM eds Encyclopedia of marine mammals 2nd Ed Academic Press pp 721 726 ISBN 9780128043813 Best P 2007 Whales and dolphins of the southern African subregion Cambridge Cambridge University Press Heyning JE 1984 Functional morphology involved in intraspecific fighting of the beaked whale Mesoplodon carlhubbsi Canadian Journal of Zoology 62 8 1645 1654 doi 10 1139 z84 239 Culik B 2011 Perrin ed Odontocetes The Toothed Whales CMS Technical Series No 24 Joint Secretariat of the Convention of Migratory Species of Wild Animals and the Agreement on the Conservation of Small Cetaceans of the Baltic North East Atlantic Irish and North Seas UNEP CMS ASCOBANS ISBN 978 3 937429 92 2 Carwardine M 1995 Whales Dolphins and Porpoises London Darling Kindersley Wellard R Lightbody K Fouda L Blewitt M Riggs D Erbe C 2016 Killer whale Mesoplodon layardii Predation on Beaked Whales Mesoplodon spp in the Bremer sub basin Western Australia PLOS ONE 11 12 e0166670 doi 10 1371 journal pone 0166670 PMC 5140045 PMID 27923044 Sekiguchi K July 1996 The diet of strap toothed whales Mesoplodon layardii Journal of Zoology 239 3 453 463 doi 10 1111 j 1469 7998 1996 tb05935 x Pitman R 2002 Mesoplodont whales In Perrin WF Wursig B Thewissen JGM eds Encyclopedia of marine mammals 1st Ed Academic Press pp 738 742 Pitman R 2009 Mesoplodont whales In Perrin WF Wursig B Thewissen JGM eds Encyclopedia of marine mammals 2nd Ed Academic Press pp 721 726 ISBN 9780128043813 Rommel SA Costidis AM Fernandez A Jepson PD Pabst DA McLellan WA Houser DS Cranford TW van Helden AL Allan DM Barros NB 2006 Elements of beaked whale anatomy and diving physiology and some hypothetical causes of sonar related stranding Journal of Cetacean Research and Management 7 3 189 209 doi 10 1111 mms 12575 S2CID 91325604 Filadelfo R Mintz J Michlovich E D Amico A Tyack PL Ketten 2009 Correlating Military Sonar Use with Beaked Whale Mass Strandings What Do the Historical Data Show Aquatic Mammals 35 4 435 444 doi 10 1578 AM 35 4 2009 435 Encyclopedia of Marine Mammals Edited by William F Perrin Bernd Wursig and J G M Thewissen Academic Press 2002 ISBN 0 12 551340 2External links Edit Wikimedia Commons has media related to Mesoplodon layardii Photo of skull of straptoothed whale Factsheets Strap toothed whale discussed on RNZ Critter of the Week 10 March 2023 Cetaceans of the World Archived 2007 03 03 at the Wayback Machine Retrieved from https en wikipedia org w index php title Strap toothed whale amp oldid 1162301116, wikipedia, wiki, book, books, library,
