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Leopard seal

January 26, 2023

The leopard seal (Hydrurga leptonyx), also referred to as the sea leopard,[3] is the second largest species of seal in the Antarctic (after the southern elephant seal). Its only natural predator is the orca.[4] It feeds on a wide range of prey including cephalopods, other pinnipeds, krill, fish, and birds, particularly penguins. It is the only species in the genus Hydrurga. Its closest relatives are the Ross seal, the crabeater seal and the Weddell seal, which together are known as the tribe of Lobodontini seals.[5][6] The name hydrurga means "water worker" and leptonyx is the Greek for "thin-clawed".

Leopard seal[1]
Temporal range: 5–0 Ma
↓
Early Pliocene – Recent
At the Antarctic Sound, near Brown Bluff, Tabarin Peninsula
Size compared to a 1.82 m (6ft) human
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Clade: Pinnipedia
Family: Phocidae
Subfamily: Monachinae
Tribe: Lobodontini
Genus: Hydrurga
Gistel, 1848
Species:
H. leptonyx
Binomial name
Hydrurga leptonyx
(Blainville, 1820)
Hydrurga leptonyx range map
Synonyms
  • homei (Lesson, 1828)
  • leptonyz (de Blainville, 1820)

Taxonomy

French zoologist Henri Marie Ducrotay de Blainville described the leopard seal in 1820.

Description

 
The skull of the leopard seal

The leopard seal has a distinctively long and muscular body shape when compared to other seals, but it is perhaps best known for its massive jaws, which allow it to be one of the top predators in its environment.[7] The front teeth are sharp like those of other carnivores, but their molars lock together in a way that allows them to sieve krill from the water in the manner of the crabeater seal. The coat is counter-shaded with a silver to dark gray blend and a distinctive spotted "leopard" coloration pattern dorsally and a paler, white to light gray color ventrally.[7] Females are slightly larger than males.[8] The overall length of adults is 2.4–3.5 m (7.9–11.5 ft) and weight is from 200 to 600 kilograms (440 to 1,320 lb) making them the same length as the northern walrus but usually less than half the weight.[9][10] The whiskers are short and clear.

As "true" seals, they do not have external ears or pinnae, but possess an internal ear canal that leads to an external opening.[11] Their hearing in air is similar to that of a human, but scientists have noted that leopard seals use their ears in conjunction with their whiskers to track prey under water.[11]

Distribution

Leopard seals are pagophilic ("ice-loving") seals, which primarily inhabit the Antarctic pack ice between 50˚S and 80˚S. Sightings of vagrant leopard seals have been recorded on the coasts of Australia, New Zealand (where individuals have been seen even on the foreshores of major cities such as Auckland,[12] Dunedin[13] and Wellington[14]), South America, and South Africa.[11] In August 2018, an individual was sighted at Geraldton, on the west coast of Australia. Higher densities of leopard seals are seen in the Western Antarctic than in other regions.[15][16]

Most leopard seals remain within the pack ice throughout the year and remain solitary during most of their lives with the exception of a mother and her newborn pup.[17][11][18] These matrilineal groups can move further north in the austral winter to sub-antarctic islands and the coastlines of the southern continents to provide care for their pups.[11] While solitary animals may appear in areas of lower latitudes, females rarely breed there. Some researchers believe this is due to safety concerns for the pups.[19] Lone male leopard seals hunt other marine mammals and penguins in the pack ice of antarctic waters. The estimated population of this species ranges from 220,000 to 440,000 individuals, putting leopard seals at "least concern".[11] Although there is an abundance of leopard seals in the Antarctic, they are difficult to survey by traditional visual techniques[20] because they spend long periods of time vocalizing under the water during the austral spring and summer, when visual surveys are carried out. The trait of vocalizing underwater for long periods means they can be the subject of acoustic surveys, allowing researchers to gather most of what is known about them.[21]

Behavior

 
A leopard seal displaying its teeth.

Acoustic behavior

Leopard seals are very vocal underwater during the austral summer.[21] The male seals produce loud calls (153 to 177 dB re 1 μPa at 1 m) for many hours each day.[22] While singing the seal hangs upside down and rocks from side to side under the water. Their back is bent, the neck and cranial thoracic region (the chest) is inflated and as they call their chest pulses. The male calls can be split into two categories: vocalizing and silencing, in which vocalizing is when they are making noises underwater, and silencing noted as the breathing period at the air surface.[23] Adult male leopard seals have only a few stylized calls, some are like bird or cricket-like trills yet others are low haunting moans.[24] Scientists have identified five distinctive sounds that male leopard seals make, which include: the high double trill, medium single trill, low descending trill, low double trill, and a hoot with a single low trill. These cadence of calls are believed to be a part of a long range acoustic display for territorial purposes, or the attraction of a potential mate.[23]

The leopard seals have age-related differences in their calling patterns, just like birds. Where the younger male seals have many different types of variable calls – the adult male seals have only a few, highly stylized calls.[25] Each male leopard seal produces these individual calls, and can arrange their few call types into individually distinctive sequences (or songs).[26] The acoustic behavior of the leopard seal is believed to be linked to their breeding behaviour. In male seals, vocalizing coincides with the timing of their breeding season, which falls between November and the first week of January; captive female seals vocalize when they have elevated reproductive hormones.[24] Conversely, a female leopard seal can attribute calls to their environment as well; however, usually it is to gain the attention of a pup, after getting back from a forage for food.

Breeding habits

 
A mother leopard seal with her pup.

Since leopard seals live in an area difficult for humans to survive in, not much is known on their reproduction and breeding habits. However, it is known that their breeding system is polygynous, meaning that males mate with multiple females during the mating period. A sexually active female (ages 3–7) can give birth to a single pup during the summer on the floating ice floes of the Antarctic pack ice, with a sexually active male (ages 6–7). Mating occurs from December to January, shortly after the pups are weaned when the female seal is in estrus.[27] In preparation for the pups, the females dig a circular hole in the ice as a home for the pup. A newborn pup weighs around 66 pounds and are usually with their mother for a month, before they are weaned off. The male leopard seal does not participate in taking care of the pup, and goes back to its solitary lifestyle after the breeding season.[11] Most leopard seal breeding is on pack ice.[28]

Five research voyages were made to Antarctica in 1985, 1987 and 1997–1999 to look at leopard seals.[28] They sighted seal pups from the beginning of November to the end of December, and noticed that there was about one pup for every three adults, and they also noticed that most of the adults were staying away from other adults during this season, and when they were seen in groups they showed no sign of interaction.[29] Leopard seal pups mortality rate within the first year is close to 25%.[30]

Vocalization is thought to be important in breeding, since males are much more vocal around this time. Mating takes place in the water, and then the male leaves the female to care for the pup, which the female gives birth to after an average gestation period of 274 days.[27]

Research shows that on average, the aerobic dive limit for juvenile seals is around 7 minutes, which means that during the winter months juvenile leopard seals do not eat krill, which is a major part of older seals' diets, since krill is found deeper during this time.[31] This might occasionally lead to co-operative hunting. Co-operative hunting of leopard seals on Antarctic fur seal pups has been witnessed, which could be a mother helping her older pup, or could also be female-male couple interactions, to increase their hunting productivity.[32]

Foraging behavior

Video of a leopard seal swimming and looking for emperor penguins in Antarctica, from Watanabe et al., Activity Time Budget during Foraging Trips of Emperor Penguins
 
A leopard seal attacking an emperor penguin

The only natural predator of leopard seals is the orca.[4] The seal's canine teeth are up to 2.5 cm (1 in) long.[33] It feeds on a wide variety of creatures. Young leopard seals usually eat mostly krill, squid and fish. Adult seals probably switch from krill to more substantial prey, including king, Adélie, rockhopper, gentoo, emperor and chinstrap penguins, and less frequently, Weddell, crabeater, Ross, and young southern elephant seals. Leopard seals are also known to take fur seal pups.[34]

Around the sub-Antarctic island of South Georgia, the Antarctic fur seal (Arctocephalus gazella) is the main prey. Other prey include penguins and fish including chondrichthyans.[35] Antarctic krill (Euphausia superba), southern elephant seal (Mirounga leonina) pups and seabirds other than penguins have also been taken as prey.[36]

When hunting penguins, the leopard seal patrols the waters near the edges of the ice, almost completely submerged, waiting for the birds to enter the ocean. It kills the swimming bird by grabbing the feet, then shaking the penguin vigorously and beating its body against the surface of the water repeatedly until the penguin is dead. Previous reports stating the leopard seal skins its prey before feeding have been found to be incorrect. Lacking the teeth necessary to slice its prey into manageable pieces, it flails its prey from side to side tearing and ripping it into smaller pieces. Krill meanwhile, is eaten by suction, and strained through the seal's teeth, allowing leopard seals to switch to different feeding styles. Such generalization and adaptations may be responsible for the seal's success in the challenging Antarctic ecosystem.[37]

Physiology and research

Leopard seals' heads and front flippers are extremely large in comparison to other phocids. Their large front flippers are used to steer themselves through the water column making them extremely agile while hunting. They use their front flippers similarly to sea lions (otariids)[38] and leopard seal females are larger than males.[39] They are covered in a thick layer of blubber that helps to keep them warm while in the cold temperatures of the Antarctic. This layer of blubber also helps to streamline their body making them more hydrodynamic. This is essential when hunting small prey items such as penguins because speed is necessary. Scientists take blubber thickness, girth, weight, and length measurements of leopard seals to learn about their average weight, health, and population as a whole.[40] These measurements are then used to calculate their energetics which is the amount of energy and food it takes for them to survive as a species. They also have incredible diving capabilities. This information can be obtained by scientists by attaching transmitters to the seals after they are tranquilized on the ice. These devices are called satellite-linked time depth recorders (SLDRs) and time-depth recorders (TDRs). Scientists attach this device usually to the head of the animal and it records depth, bottom time, total dive time, date and time, surface time, haul out time, pitch and roll, and total number of dives.[41] This information is sent to a satellite where scientists from anywhere in the world can collect the data. This is how we are currently learning so much about leopard seals diet and foraging habits. With this information we are able to calculate and better understand their diving physiology. They are primarily shallow divers but they do dive deeper than 80 meters in search for food.[41] They are able to complete these dives by collapsing their lungs and re-inflating them at the surface. This is possible by increasing surfactant which coats the alveoli in the lungs for re-inflation. They also have a reinforced trachea to prevent collapse at great depth pressures.[42]

Relationships with humans

Leopard seals are large predators presenting a potential risk to humans. However, attacks on humans are rare. Most human perceptions of leopard seals are shaped by historic encounters between humans and leopard seals that occurred during the early days of Antarctic exploration.[43]

Negative interactions with humans

Examples of aggressive behaviour, stalking and attacks are rare, but have been documented.[44] Notable incidents include:

  • A large leopard seal attacked Thomas Orde-Lees (1877–1958), a member of Sir Ernest Shackleton's Imperial Trans-Antarctic Expedition of 1914–1917, when the expedition was camping on the sea ice.[45] The "sea leopard", about 12 ft (3.7 m) long and 1,100 lb (500 kg), chased Orde-Lees on the ice. He was saved only when another member of the expedition, Frank Wild, shot the animal.[46]
  • In 1985, Canadian-British explorer Gareth Wood was bitten twice on the leg when a leopard seal tried to drag him off the ice and into the sea. His companions managed to save him by repeatedly kicking the animal in the head with the spiked crampons on their boots.[45][44]
  • On 26 September 2021, near the dive site Spaniard Rock at Simon's Town, South Africa, three spear-fisherman encountered a leopard seal while spearing approximately 400 m offshore. The seal attacked them and, while they were swimming back to shore, disarmed them of their flippers and spearguns and kept harassing the men over the course of half an hour, inflicting multiple bite and puncture wounds.[47]

Fatal interactions

In 2003, biologist Kirsty Brown of the British Antarctic Survey was killed by a leopard seal while snorkeling in Antarctica. This was the first recorded human fatality from a leopard seal.[45][44] Brown was part of a team of four researchers taking part in an underwater survey at South Cove near the U.K.'s Rothera Research Station. Brown and another researcher, Richard Burt, were snorkeling in the water. Burt was snorkeling 15 meters away when the team heard a scream and saw Brown disappear into the water. She was quickly rescued by her team but they were unable to resuscitate her. It was later revealed that the seal had held her underwater for six minutes at a depth of up to 70 meters. She suffered a total of 45 separate injuries most of which were concentrated around her head and neck. As she was snorkeling at the time she may have seen the seal approaching her.

In a report read at the inquiry into Brown's death, Professor Ian Boyd from St. Andrews University stated that the seal may have mistaken her for a fur seal or may have been frightened by her presence and attacked in defense. Professor Boyd claimed that leopard seal attacks on humans were extremely rare but warned that they may potentially become more common due to increased human presence in Antarctica. The coroner recorded a verdict of an accidental death caused by drowning due to a leopard seal attack.[48]

Interactions with human property

Leopard seals have shown a predilection for attacking the black, torpedo-shaped pontoons of rigid inflatable boats, leading researchers to equip their craft with special protective guards to prevent them from being punctured.[44][49]

Positive interactions with humans

Paul Nicklen, a National Geographic magazine photographer, captured pictures of a leopard seal bringing live, injured, and then dead penguins to him, possibly in an attempt to teach the photographer how to hunt.[50]

Conservation

From a conservation standpoint, the only known predators of the leopard seals are killer whales and sharks. Because of their limited subpolar distribution in the Antarctic, they may be at risk as polar ice caps diminish with global warming. In the wild, leopard seals can live up to 26 years old.[51] Leopard seal hunting is regulated by the Antarctic Treaty and the Convention for the Conservation of Antarctic Seals (CCAS).[30]

Notes and references

  1. ^ Wilson, Don E.; Seeder, Dee Ann M., eds. (2005). "Species: Hydrurga leptonyx". Mammal species of the world : a taxonomic and geographic reference (3rd ed.). Baltimore: Johns Hopkins University Press. ISBN 978-0-8018-8221-0.
  2. ^ Hückstädt, L. (2015). "Hydrurga leptonyx". IUCN Red List of Threatened Species. 2015: e.T10340A45226422. doi:10.2305/IUCN.UK.2015-4.RLTS.T10340A45226422.en. Retrieved 20 February 2022.
  3. ^ "Leopard seal". Encyclopedia Britannica. 1998.
  4. ^ a b "Leopard seals". Australian Antarctic Division. Retrieved 14 August 2017.
  5. ^ Wilson, Don E.; Reeder, DeeAnn M., eds. (2005). "Family: Phocidae". Mammal species of the world : a taxonomic and geographic reference (3rd ed.). Baltimore: Johns Hopkins University Press. ISBN 978-0-8018-8221-0.
  6. ^ Berta, Annalisa (2009). "Pinnipedia: Overview". In Perrin, W. F.; Würsig, B.; Thewissen, J. G. M. (eds.). Encyclopedia of Marine Mammals (2nd ed.). Academic Press. pp. 878–85. ISBN 978-0-12-373553-9.
  7. ^ a b "Marine Species Identification Portal : Leopard seal - Hydrurga leptonyx". species-identification.org. Retrieved 2018-03-19.
  8. ^ Tunstall, T. "Hydrurga leptonyx". Animal Diversity Web. University of Michigan Museum of Zoology. Retrieved 2009-04-27.
  9. ^ Nowak, Ronald M (2003). Walker's Marine Mammals of the World. Johns Hopkins University Press: Baltimore, MD.
  10. ^ Leopard Seals, Hydrurga leptonyx. marinebio.org
  11. ^ a b c d e f g "Leopard seal | TravelWild Expeditions". TravelWild Expeditions. Retrieved 2018-04-18.
  12. ^ "Leopard seal". www.doc.govt.nz. Retrieved 2020-02-24.
  13. ^ MacLean, Hamish (2019-01-19). "Leopard seal sightings in New Zealand on the rise". Otago Daily Times Online News. Retrieved 2020-02-24.
  14. ^ "Antarctic Leopard seal turns up on Wellington's Lyall bay beach".
  15. ^ Southwell, C.; Bengtson, J.; Bester, M.; Schytte Blix, A.; Bornemann, H.; Boveng, P.; Cameron, M.; Forcada, J.; Laake, J.; Nordøy, E.; Plötz, J.; Rogers, T.; Southwell, D.; Steinhage, D.; Stewart, B.S.; Trathan, P (2012). "A review of data on abundance, trends in abundance, habitat use and diet of ice-breeding seals in the Southern Ocean". CCAMLR Science. 19: 1–26.
  16. ^ Forcada, J.; Trathan, P.; Boveng, Boyd; I., Burns; J., Costa; D., Fedak; M., Rogers; T., Southwell, C. (2012). "Responses of Antarctic pack-ice seals to environmental change and increasing krill fishing". Biological Conservation. 149 (1): 40–50. doi:10.1016/j.biocon.2012.02.002. S2CID 7892053.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  17. ^ Rogers, T.L.; Hogg, C. & Irvine, A. (2005). "Spatial movement of adult leopard seals (Hydrurga leptonyx) in Prydz Bay, Eastern Antarctica". Polar Biology. 28 (6): 456–463. doi:10.1007/s00300-004-0703-4. S2CID 22535400.
  18. ^ Meade, J.; Ciaglia, M.B.; Slip, D.J.; Negrete, J.; Márquez M.E.I., Rogers, T. (2015). "Spatial patterns in activity of leopard seals Hydrurga leptonyx in relation to sea ice". Marine Ecology Progress Series. 521: 265–275. Bibcode:2015MEPS..521..265M. doi:10.3354/meps11120. S2CID 87706193.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  19. ^ Taylor, Margot (2017-09-27). "Odds against St Kilda leopard seal pup". Otago Daily Times. Retrieved 2020-07-25.
  20. ^ Southwell, C.; Paxton, C.; Borchers, D.; Boveng, P. Rogers, T. & de la Mare, W. (2008). "Uncommon or cryptic? Challenges in estimating leopard seal abundance by conventional but state-of-the-art methods". Deep-Sea Research Part I: Oceanographic Research Papers. 55 (4): 519–531. Bibcode:2008DSRI...55..519S. doi:10.1016/j.dsr.2008.01.005.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  21. ^ a b Rogers TL, Ciaglia MB, Klinck H, Southwell C (2013). "Density Can Be Misleading for Low-Density Species: Benefits of Passive Acoustic Monitoring". PLOS ONE. 8 (1): e52542. Bibcode:2013PLoSO...852542R. doi:10.1371/journal.pone.0052542. PMC 3541380. PMID 23326339.
  22. ^ Rogers TL (2014). "Source levels of the underwater calls of a male leopard seal". The Journal of the Acoustical Society of America. 136 (4): 1495–1498. Bibcode:2014ASAJ..136.1495R. doi:10.1121/1.4895685. PMID 25324053.
  23. ^ a b Rogers, Tracey L.; Cato, Douglas H. (2002). "Individual Variation in the Acoustic Behaviour of the Adult Male Leopard Seal, Hydrurga leptonyx". Behaviour. 139 (10): 1267–1286. doi:10.1163/156853902321104154. JSTOR 4535987.
  24. ^ a b Rogers, T. L.; Cato, D. H. & Bryden, M. M. (1996). "Behavioral significance of underwater vocalizations of captive leopard seals, Hydrurga leptonyx". Marine Mammal Science. 12 (3): 414–427. doi:10.1111/j.1748-7692.1996.tb00593.x.
  25. ^ Rogers, T. L (2007). "Age-related differences in the acoustic characteristics of male leopard seals, Hydrurga leptonyx". The Journal of the Acoustical Society of America. 122 (1): 596–605. Bibcode:2007ASAJ..122..596R. doi:10.1121/1.2736976. PMID 17614516.
  26. ^ Rogers, Tracey L.; Cato, Douglas H. (2002). "Individual Variation in the Acoustic Behaviour of the Adult Male Leopard Seal, Hydrurga leptonyx". Behaviour. 139 (10): 1267–1286. doi:10.1163/156853902321104154. JSTOR 4535987.
  27. ^ a b "Reproduction - Encyclopedia of Life". Encyclopedia of Life. Retrieved 2018-05-15.
  28. ^ a b Southwell, Colin; Kerry, Knowles; Ensor, Paul; Woehler, Eric J.; Rogers, Tracey (2003). "The timing of pupping by pack-ice seals in East Antarctica". Polar Biology. 26 (10): 648–652. doi:10.1007/s00300-003-0534-8. S2CID 7565646.
  29. ^ Borsa, Philippe (1990). "Seasonal occurrence of the leopard seal, Hydrurga leptonyx, in the Kerguelen Islands". Canadian Journal of Zoology. 68 (2): 405–408. doi:10.1139/z90-059.
  30. ^ a b Administrator. "Leopard Seal". www.pinnipeds.org. Retrieved 2018-06-04.
  31. ^ Kuhn, Carey E.; McDonald, Birgitte I.; Shaffer, Scott A.; Barnes, Julie; Crocker, Daniel E.; Burns, Jennifer; Costa, Daniel P. (2005). "Diving physiology and winter foraging behavior of a juvenile leopard seal (Hydrurga leptonyx)". Polar Biology. 29 (4): 303–307. doi:10.1007/s00300-005-0053-x. S2CID 32195795.
  32. ^ Hiruki, Lisa M.; Schwartz, Michael K.; Boveng, Peter L. (1999). "Hunting and social behaviour of leopard seals (Hydrurga leptonyx) at Seal Island, South Shetland Islands, Antarctica". Journal of Zoology. 249 (1): 97–109. doi:10.1111/j.1469-7998.1999.tb01063.x.
  33. ^ Kindersley, Dorling (2005) [2001]. Animal. New York City: DK Publishing. ISBN 978-0-7894-7764-4.
  34. ^ "POV: Why Are Leopard Seals Eating Fur Seal Pups?". video.nationalgeographic.com. Retrieved 2015-08-08.
  35. ^ Van Der Linde, Krista; Visser, Ingrid N.; Bout, Rick; Lalas, Chris; Shepherd, Lara; Hocking, David; Finucci, Brittany; Fyfe, Jim; Pinkerton, Matthew (2021). "Leopard Seals (Hydrurga leptonyx) in New Zealand waters predating on chondrichthyans". Frontiers in Marine Science. 8. doi:10.3389/fmars.2021.795358.
  36. ^ Walker, T.R.; Boyd, I.L.; Mccafferty, D.J.; Huin, N.; Taylor, R.I.; Reid, K. (1998). "Seasonal occurrence and diet of leopard seals (Hydrurga leptonyx) at Bird Island, South Georgia". Antarctic Science. 10 (1): 75–81. Bibcode:1998AntSc..10...75W. doi:10.1017/S0954102098000108. S2CID 85575118.
  37. ^ Yong, Ed (2012). "Leopard seals suck up krill like whales". Nature. doi:10.1038/nature.2012.11672. S2CID 87484971.
  38. ^ "Leopard Seals". NOAA Fisheries National Oceanic and Atmospheric Administration Alaska Fisheries Science Center. 27 January 2021.
  39. ^ "Leopard Seals, Hydrurga leptonyx". Marine Bio.
  40. ^ Krause, Douglas J.; Hinke, Jefferson T.; Perryman, Wayne L.; Goebel, Michael E.; LeRoi, Donald J. (2017-11-29). "An accurate and adaptable photogrammetric approach for estimating the mass and body condition of pinnipeds using an unmanned aerial system". PLOS ONE. 12 (11): e0187465. Bibcode:2017PLoSO..1287465K. doi:10.1371/journal.pone.0187465. PMC 5706667. PMID 29186134.
  41. ^ a b Krause, Douglas J.; Goebel, Michael E.; Marshall, Greg J.; Abernathy, Kyler (2016-02-24). "Summer diving and haul-out behavior of leopard seals (Hydrurga leptonyx) near mesopredator breeding colonies at Livingston Island, Antarctic Peninsula". Marine Mammal Science. 32 (3): 839–867. doi:10.1111/mms.12309. ISSN 0824-0469.
  42. ^ "Respiration and Diving Physiology" (PDF). Cetus UCSD.
  43. ^ Muir, Shona F.; Barnes, David K.A.; Reid, Keith (2006). "Interactions between humans and leopard seals". Antarctic Science. 18 (1): 61–74. Bibcode:2006AntSc..18...61M. doi:10.1017/S0954102006000058. S2CID 53648359.
  44. ^ a b c d Owen, James (August 6, 2003). "Leopard Seal Kills Scientist in Antarctica". National Geographic Society. Retrieved 2007-12-10.
  45. ^ a b c Carrington, Damian (2003-07-24). Inquiry into fatal leopard seal attack begins. NewScientist.com. Retrieved on 2013-02-24.
  46. ^ Shackleton, Ernest (1998). South. New York, NY: The Lyons Press. p. 112. ISBN 1-55821-783-5.
  47. ^ "NSRI appeal to the public to be cautious around seals and sea animals in general". National Sea Rescue Institute. Retrieved 1 October 2021.
  48. ^ Gyford, Sue (2003-11-14). [1]. ecophotoexplorers.com. Retrieved on 2019-08-20
  49. ^ Briggs, Mike; Briggs, Peggy (2005). The Encyclopedia of World Wildlife. Parragon. p. 60. ISBN 978-1-40545-680-7.
  50. ^ National Geographic photographer's surprise encounter with deadly predator. dpreview.com (2012-10-18)
  51. ^ "Leopard Seal - Seal Facts and Information". www.seals-world.com. Retrieved 2018-04-18.

General references

  • Rogers, Tracey L. (2009). "The leopard seal, Hydrurga leptonyx". In Perrin, W. F.; Würsig, B.; Thewissen, J. G. M. (eds.). Encyclopedia of Marine Mammals (2nd ed.). Academic Press. ISBN 978-0-12-373553-9.
  • Heacox, Kim. (2006). National Geographic, November 2006
  • Saundry, Peter. (2010) Leopard Seal. Encyclopedia of Earth. Topic ed. C. Michael Hogan, editor-in-chief Cutler Cleveland, NCSE, Washington DC

External links

 
Wikimedia Commons has media related to Leopard Seal.
 
Wikispecies has information related to Hydrurga leptonyx.
 
Wikisource has the text of the 1905 New International Encyclopedia article "Sea-leopard".
  • Best Wildlife Photos of 2005 – "Underwater World" Winner: "Leopard Seal Pass"
  • "Face-off with a deadly predator" (video); National Geographic photo assignment
  • Voices in the Sea – the Leopard Seal (audio)

January 26, 2023
leopard, seal, leopard, seal, hydrurga, leptonyx, also, referred, leopard, second, largest, species, seal, antarctic, after, southern, elephant, seal, only, natural, predator, orca, feeds, wide, range, prey, including, cephalopods, other, pinnipeds, krill, fis. The leopard seal Hydrurga leptonyx also referred to as the sea leopard 3 is the second largest species of seal in the Antarctic after the southern elephant seal Its only natural predator is the orca 4 It feeds on a wide range of prey including cephalopods other pinnipeds krill fish and birds particularly penguins It is the only species in the genus Hydrurga Its closest relatives are the Ross seal the crabeater seal and the Weddell seal which together are known as the tribe of Lobodontini seals 5 6 The name hydrurga means water worker and leptonyx is the Greek for thin clawed Leopard seal 1 Temporal range 5 0 Ma PreꞒ Ꞓ O S D C P T J K Pg N Early Pliocene RecentAt the Antarctic Sound near Brown Bluff Tabarin PeninsulaSize compared to a 1 82 m 6ft humanConservation statusLeast Concern IUCN 3 1 2 Scientific classificationKingdom AnimaliaPhylum ChordataClass MammaliaOrder CarnivoraClade PinnipediaFamily PhocidaeSubfamily MonachinaeTribe LobodontiniGenus HydrurgaGistel 1848Species H leptonyxBinomial nameHydrurga leptonyx Blainville 1820 Hydrurga leptonyx range mapSynonymshomei Lesson 1828 leptonyz de Blainville 1820 Contents 1 Taxonomy 2 Description 3 Distribution 4 Behavior 4 1 Acoustic behavior 4 2 Breeding habits 4 3 Foraging behavior 5 Physiology and research 6 Relationships with humans 6 1 Negative interactions with humans 6 1 1 Fatal interactions 6 1 2 Interactions with human property 6 2 Positive interactions with humans 7 Conservation 8 Notes and references 9 General references 10 External linksTaxonomy EditFrench zoologist Henri Marie Ducrotay de Blainville described the leopard seal in 1820 Description Edit The skull of the leopard seal The leopard seal has a distinctively long and muscular body shape when compared to other seals but it is perhaps best known for its massive jaws which allow it to be one of the top predators in its environment 7 The front teeth are sharp like those of other carnivores but their molars lock together in a way that allows them to sieve krill from the water in the manner of the crabeater seal The coat is counter shaded with a silver to dark gray blend and a distinctive spotted leopard coloration pattern dorsally and a paler white to light gray color ventrally 7 Females are slightly larger than males 8 The overall length of adults is 2 4 3 5 m 7 9 11 5 ft and weight is from 200 to 600 kilograms 440 to 1 320 lb making them the same length as the northern walrus but usually less than half the weight 9 10 The whiskers are short and clear As true seals they do not have external ears or pinnae but possess an internal ear canal that leads to an external opening 11 Their hearing in air is similar to that of a human but scientists have noted that leopard seals use their ears in conjunction with their whiskers to track prey under water 11 Distribution EditLeopard seals are pagophilic ice loving seals which primarily inhabit the Antarctic pack ice between 50 S and 80 S Sightings of vagrant leopard seals have been recorded on the coasts of Australia New Zealand where individuals have been seen even on the foreshores of major cities such as Auckland 12 Dunedin 13 and Wellington 14 South America and South Africa 11 In August 2018 an individual was sighted at Geraldton on the west coast of Australia Higher densities of leopard seals are seen in the Western Antarctic than in other regions 15 16 Most leopard seals remain within the pack ice throughout the year and remain solitary during most of their lives with the exception of a mother and her newborn pup 17 11 18 These matrilineal groups can move further north in the austral winter to sub antarctic islands and the coastlines of the southern continents to provide care for their pups 11 While solitary animals may appear in areas of lower latitudes females rarely breed there Some researchers believe this is due to safety concerns for the pups 19 Lone male leopard seals hunt other marine mammals and penguins in the pack ice of antarctic waters The estimated population of this species ranges from 220 000 to 440 000 individuals putting leopard seals at least concern 11 Although there is an abundance of leopard seals in the Antarctic they are difficult to survey by traditional visual techniques 20 because they spend long periods of time vocalizing under the water during the austral spring and summer when visual surveys are carried out The trait of vocalizing underwater for long periods means they can be the subject of acoustic surveys allowing researchers to gather most of what is known about them 21 Behavior Edit A leopard seal displaying its teeth Acoustic behavior Edit Leopard seals are very vocal underwater during the austral summer 21 The male seals produce loud calls 153 to 177 dB re 1 mPa at 1 m for many hours each day 22 While singing the seal hangs upside down and rocks from side to side under the water Their back is bent the neck and cranial thoracic region the chest is inflated and as they call their chest pulses The male calls can be split into two categories vocalizing and silencing in which vocalizing is when they are making noises underwater and silencing noted as the breathing period at the air surface 23 Adult male leopard seals have only a few stylized calls some are like bird or cricket like trills yet others are low haunting moans 24 Scientists have identified five distinctive sounds that male leopard seals make which include the high double trill medium single trill low descending trill low double trill and a hoot with a single low trill These cadence of calls are believed to be a part of a long range acoustic display for territorial purposes or the attraction of a potential mate 23 The leopard seals have age related differences in their calling patterns just like birds Where the younger male seals have many different types of variable calls the adult male seals have only a few highly stylized calls 25 Each male leopard seal produces these individual calls and can arrange their few call types into individually distinctive sequences or songs 26 The acoustic behavior of the leopard seal is believed to be linked to their breeding behaviour In male seals vocalizing coincides with the timing of their breeding season which falls between November and the first week of January captive female seals vocalize when they have elevated reproductive hormones 24 Conversely a female leopard seal can attribute calls to their environment as well however usually it is to gain the attention of a pup after getting back from a forage for food Breeding habits Edit A mother leopard seal with her pup Since leopard seals live in an area difficult for humans to survive in not much is known on their reproduction and breeding habits However it is known that their breeding system is polygynous meaning that males mate with multiple females during the mating period A sexually active female ages 3 7 can give birth to a single pup during the summer on the floating ice floes of the Antarctic pack ice with a sexually active male ages 6 7 Mating occurs from December to January shortly after the pups are weaned when the female seal is in estrus 27 In preparation for the pups the females dig a circular hole in the ice as a home for the pup A newborn pup weighs around 66 pounds and are usually with their mother for a month before they are weaned off The male leopard seal does not participate in taking care of the pup and goes back to its solitary lifestyle after the breeding season 11 Most leopard seal breeding is on pack ice 28 Five research voyages were made to Antarctica in 1985 1987 and 1997 1999 to look at leopard seals 28 They sighted seal pups from the beginning of November to the end of December and noticed that there was about one pup for every three adults and they also noticed that most of the adults were staying away from other adults during this season and when they were seen in groups they showed no sign of interaction 29 Leopard seal pups mortality rate within the first year is close to 25 30 Vocalization is thought to be important in breeding since males are much more vocal around this time Mating takes place in the water and then the male leaves the female to care for the pup which the female gives birth to after an average gestation period of 274 days 27 Research shows that on average the aerobic dive limit for juvenile seals is around 7 minutes which means that during the winter months juvenile leopard seals do not eat krill which is a major part of older seals diets since krill is found deeper during this time 31 This might occasionally lead to co operative hunting Co operative hunting of leopard seals on Antarctic fur seal pups has been witnessed which could be a mother helping her older pup or could also be female male couple interactions to increase their hunting productivity 32 Foraging behavior Edit source source source source source source source source source source Video of a leopard seal swimming and looking for emperor penguins in Antarctica from Watanabe et al Activity Time Budget during Foraging Trips of Emperor Penguins A leopard seal attacking an emperor penguin The only natural predator of leopard seals is the orca 4 The seal s canine teeth are up to 2 5 cm 1 in long 33 It feeds on a wide variety of creatures Young leopard seals usually eat mostly krill squid and fish Adult seals probably switch from krill to more substantial prey including king Adelie rockhopper gentoo emperor and chinstrap penguins and less frequently Weddell crabeater Ross and young southern elephant seals Leopard seals are also known to take fur seal pups 34 Around the sub Antarctic island of South Georgia the Antarctic fur seal Arctocephalus gazella is the main prey Other prey include penguins and fish including chondrichthyans 35 Antarctic krill Euphausia superba southern elephant seal Mirounga leonina pups and seabirds other than penguins have also been taken as prey 36 When hunting penguins the leopard seal patrols the waters near the edges of the ice almost completely submerged waiting for the birds to enter the ocean It kills the swimming bird by grabbing the feet then shaking the penguin vigorously and beating its body against the surface of the water repeatedly until the penguin is dead Previous reports stating the leopard seal skins its prey before feeding have been found to be incorrect Lacking the teeth necessary to slice its prey into manageable pieces it flails its prey from side to side tearing and ripping it into smaller pieces Krill meanwhile is eaten by suction and strained through the seal s teeth allowing leopard seals to switch to different feeding styles Such generalization and adaptations may be responsible for the seal s success in the challenging Antarctic ecosystem 37 Physiology and research EditLeopard seals heads and front flippers are extremely large in comparison to other phocids Their large front flippers are used to steer themselves through the water column making them extremely agile while hunting They use their front flippers similarly to sea lions otariids 38 and leopard seal females are larger than males 39 They are covered in a thick layer of blubber that helps to keep them warm while in the cold temperatures of the Antarctic This layer of blubber also helps to streamline their body making them more hydrodynamic This is essential when hunting small prey items such as penguins because speed is necessary Scientists take blubber thickness girth weight and length measurements of leopard seals to learn about their average weight health and population as a whole 40 These measurements are then used to calculate their energetics which is the amount of energy and food it takes for them to survive as a species They also have incredible diving capabilities This information can be obtained by scientists by attaching transmitters to the seals after they are tranquilized on the ice These devices are called satellite linked time depth recorders SLDRs and time depth recorders TDRs Scientists attach this device usually to the head of the animal and it records depth bottom time total dive time date and time surface time haul out time pitch and roll and total number of dives 41 This information is sent to a satellite where scientists from anywhere in the world can collect the data This is how we are currently learning so much about leopard seals diet and foraging habits With this information we are able to calculate and better understand their diving physiology They are primarily shallow divers but they do dive deeper than 80 meters in search for food 41 They are able to complete these dives by collapsing their lungs and re inflating them at the surface This is possible by increasing surfactant which coats the alveoli in the lungs for re inflation They also have a reinforced trachea to prevent collapse at great depth pressures 42 Relationships with humans EditLeopard seals are large predators presenting a potential risk to humans However attacks on humans are rare Most human perceptions of leopard seals are shaped by historic encounters between humans and leopard seals that occurred during the early days of Antarctic exploration 43 Negative interactions with humans Edit Examples of aggressive behaviour stalking and attacks are rare but have been documented 44 Notable incidents include A large leopard seal attacked Thomas Orde Lees 1877 1958 a member of Sir Ernest Shackleton s Imperial Trans Antarctic Expedition of 1914 1917 when the expedition was camping on the sea ice 45 The sea leopard about 12 ft 3 7 m long and 1 100 lb 500 kg chased Orde Lees on the ice He was saved only when another member of the expedition Frank Wild shot the animal 46 In 1985 Canadian British explorer Gareth Wood was bitten twice on the leg when a leopard seal tried to drag him off the ice and into the sea His companions managed to save him by repeatedly kicking the animal in the head with the spiked crampons on their boots 45 44 On 26 September 2021 near the dive site Spaniard Rock at Simon s Town South Africa three spear fisherman encountered a leopard seal while spearing approximately 400 m offshore The seal attacked them and while they were swimming back to shore disarmed them of their flippers and spearguns and kept harassing the men over the course of half an hour inflicting multiple bite and puncture wounds 47 Fatal interactions Edit In 2003 biologist Kirsty Brown of the British Antarctic Survey was killed by a leopard seal while snorkeling in Antarctica This was the first recorded human fatality from a leopard seal 45 44 Brown was part of a team of four researchers taking part in an underwater survey at South Cove near the U K s Rothera Research Station Brown and another researcher Richard Burt were snorkeling in the water Burt was snorkeling 15 meters away when the team heard a scream and saw Brown disappear into the water She was quickly rescued by her team but they were unable to resuscitate her It was later revealed that the seal had held her underwater for six minutes at a depth of up to 70 meters She suffered a total of 45 separate injuries most of which were concentrated around her head and neck As she was snorkeling at the time she may have seen the seal approaching her In a report read at the inquiry into Brown s death Professor Ian Boyd from St Andrews University stated that the seal may have mistaken her for a fur seal or may have been frightened by her presence and attacked in defense Professor Boyd claimed that leopard seal attacks on humans were extremely rare but warned that they may potentially become more common due to increased human presence in Antarctica The coroner recorded a verdict of an accidental death caused by drowning due to a leopard seal attack 48 Interactions with human property Edit Leopard seals have shown a predilection for attacking the black torpedo shaped pontoons of rigid inflatable boats leading researchers to equip their craft with special protective guards to prevent them from being punctured 44 49 Positive interactions with humans Edit Paul Nicklen a National Geographic magazine photographer captured pictures of a leopard seal bringing live injured and then dead penguins to him possibly in an attempt to teach the photographer how to hunt 50 Conservation EditFrom a conservation standpoint the only known predators of the leopard seals are killer whales and sharks Because of their limited subpolar distribution in the Antarctic they may be at risk as polar ice caps diminish with global warming In the wild leopard seals can live up to 26 years old 51 Leopard seal hunting is regulated by the Antarctic Treaty and the Convention for the Conservation of Antarctic Seals CCAS 30 Notes and references Edit Wilson Don E Seeder Dee Ann M eds 2005 Species Hydrurga leptonyx Mammal species of the world a taxonomic and geographic reference 3rd ed Baltimore Johns Hopkins University Press ISBN 978 0 8018 8221 0 Huckstadt L 2015 Hydrurga leptonyx IUCN Red List of Threatened Species 2015 e T10340A45226422 doi 10 2305 IUCN UK 2015 4 RLTS T10340A45226422 en Retrieved 20 February 2022 Leopard seal Encyclopedia Britannica 1998 a b Leopard seals Australian Antarctic Division Retrieved 14 August 2017 Wilson Don E Reeder DeeAnn M eds 2005 Family Phocidae Mammal species of the world a taxonomic and geographic reference 3rd ed Baltimore Johns Hopkins University Press ISBN 978 0 8018 8221 0 Berta Annalisa 2009 Pinnipedia Overview In Perrin W F Wursig B Thewissen J G M eds Encyclopedia of Marine Mammals 2nd ed Academic Press pp 878 85 ISBN 978 0 12 373553 9 a b Marine Species Identification Portal Leopard seal Hydrurga leptonyx species identification org Retrieved 2018 03 19 Tunstall T Hydrurga leptonyx Animal Diversity Web University of Michigan Museum of Zoology Retrieved 2009 04 27 Nowak Ronald M 2003 Walker s Marine Mammals of the World Johns Hopkins University Press Baltimore MD Leopard Seals Hydrurga leptonyx marinebio org a b c d e f g Leopard seal TravelWild Expeditions TravelWild Expeditions Retrieved 2018 04 18 Leopard seal www doc govt nz Retrieved 2020 02 24 MacLean Hamish 2019 01 19 Leopard seal sightings in New Zealand on the rise Otago Daily Times Online News Retrieved 2020 02 24 Antarctic Leopard seal turns up on Wellington s Lyall bay beach Southwell C Bengtson J Bester M Schytte Blix A Bornemann H Boveng P Cameron M Forcada J Laake J Nordoy E Plotz J Rogers T Southwell D Steinhage D Stewart B S Trathan P 2012 A review of data on abundance trends in abundance habitat use and diet of ice breeding seals in the Southern Ocean CCAMLR Science 19 1 26 Forcada J Trathan P Boveng Boyd I Burns J Costa D Fedak M Rogers T Southwell C 2012 Responses of Antarctic pack ice seals to environmental change and increasing krill fishing Biological Conservation 149 1 40 50 doi 10 1016 j biocon 2012 02 002 S2CID 7892053 a href Template Cite journal html title Template Cite journal cite journal a CS1 maint multiple names authors list link Rogers T L Hogg C amp Irvine A 2005 Spatial movement of adult leopard seals Hydrurga leptonyx in Prydz Bay Eastern Antarctica Polar Biology 28 6 456 463 doi 10 1007 s00300 004 0703 4 S2CID 22535400 Meade J Ciaglia M B Slip D J Negrete J Marquez M E I Rogers T 2015 Spatial patterns in activity of leopard seals Hydrurga leptonyx in relation to sea ice Marine Ecology Progress Series 521 265 275 Bibcode 2015MEPS 521 265M doi 10 3354 meps11120 S2CID 87706193 a href Template Cite journal html title Template Cite journal cite journal a CS1 maint multiple names authors list link Taylor Margot 2017 09 27 Odds against St Kilda leopard seal pup Otago Daily Times Retrieved 2020 07 25 Southwell C Paxton C Borchers D Boveng P Rogers T amp de la Mare W 2008 Uncommon or cryptic Challenges in estimating leopard seal abundance by conventional but state of the art methods Deep Sea Research Part I Oceanographic Research Papers 55 4 519 531 Bibcode 2008DSRI 55 519S doi 10 1016 j dsr 2008 01 005 a href Template Cite journal html title Template Cite journal cite journal a CS1 maint multiple names authors list link a b Rogers TL Ciaglia MB Klinck H Southwell C 2013 Density Can Be Misleading for Low Density Species Benefits of Passive Acoustic Monitoring PLOS ONE 8 1 e52542 Bibcode 2013PLoSO 852542R doi 10 1371 journal pone 0052542 PMC 3541380 PMID 23326339 Rogers TL 2014 Source levels of the underwater calls of a male leopard seal The Journal of the Acoustical Society of America 136 4 1495 1498 Bibcode 2014ASAJ 136 1495R doi 10 1121 1 4895685 PMID 25324053 a b Rogers Tracey L Cato Douglas H 2002 Individual Variation in the Acoustic Behaviour of the Adult Male Leopard Seal Hydrurga leptonyx Behaviour 139 10 1267 1286 doi 10 1163 156853902321104154 JSTOR 4535987 a b Rogers T L Cato D H amp Bryden M M 1996 Behavioral significance of underwater vocalizations of captive leopard seals Hydrurga leptonyx Marine Mammal Science 12 3 414 427 doi 10 1111 j 1748 7692 1996 tb00593 x Rogers T L 2007 Age related differences in the acoustic characteristics of male leopard seals Hydrurga leptonyx The Journal of the Acoustical Society of America 122 1 596 605 Bibcode 2007ASAJ 122 596R doi 10 1121 1 2736976 PMID 17614516 Rogers Tracey L Cato Douglas H 2002 Individual Variation in the Acoustic Behaviour of the Adult Male Leopard Seal Hydrurga leptonyx Behaviour 139 10 1267 1286 doi 10 1163 156853902321104154 JSTOR 4535987 a b Reproduction Encyclopedia of Life Encyclopedia of Life Retrieved 2018 05 15 a b Southwell Colin Kerry Knowles Ensor Paul Woehler Eric J Rogers Tracey 2003 The timing of pupping by pack ice seals in East Antarctica Polar Biology 26 10 648 652 doi 10 1007 s00300 003 0534 8 S2CID 7565646 Borsa Philippe 1990 Seasonal occurrence of the leopard seal Hydrurga leptonyx in the Kerguelen Islands Canadian Journal of Zoology 68 2 405 408 doi 10 1139 z90 059 a b Administrator Leopard Seal www pinnipeds org Retrieved 2018 06 04 Kuhn Carey E McDonald Birgitte I Shaffer Scott A Barnes Julie Crocker Daniel E Burns Jennifer Costa Daniel P 2005 Diving physiology and winter foraging behavior of a juvenile leopard seal Hydrurga leptonyx Polar Biology 29 4 303 307 doi 10 1007 s00300 005 0053 x S2CID 32195795 Hiruki Lisa M Schwartz Michael K Boveng Peter L 1999 Hunting and social behaviour of leopard seals Hydrurga leptonyx at Seal Island South Shetland Islands Antarctica Journal of Zoology 249 1 97 109 doi 10 1111 j 1469 7998 1999 tb01063 x Kindersley Dorling 2005 2001 Animal New York City DK Publishing ISBN 978 0 7894 7764 4 POV Why Are Leopard Seals Eating Fur Seal Pups video nationalgeographic com Retrieved 2015 08 08 Van Der Linde Krista Visser Ingrid N Bout Rick Lalas Chris Shepherd Lara Hocking David Finucci Brittany Fyfe Jim Pinkerton Matthew 2021 Leopard Seals Hydrurga leptonyx in New Zealand waters predating on chondrichthyans Frontiers in Marine Science 8 doi 10 3389 fmars 2021 795358 Walker T R Boyd I L Mccafferty D J Huin N Taylor R I Reid K 1998 Seasonal occurrence and diet of leopard seals Hydrurga leptonyx at Bird Island South Georgia Antarctic Science 10 1 75 81 Bibcode 1998AntSc 10 75W doi 10 1017 S0954102098000108 S2CID 85575118 Yong Ed 2012 Leopard seals suck up krill like whales Nature doi 10 1038 nature 2012 11672 S2CID 87484971 Leopard Seals NOAA Fisheries National Oceanic and Atmospheric Administration Alaska Fisheries Science Center 27 January 2021 Leopard Seals Hydrurga leptonyx Marine Bio Krause Douglas J Hinke Jefferson T Perryman Wayne L Goebel Michael E LeRoi Donald J 2017 11 29 An accurate and adaptable photogrammetric approach for estimating the mass and body condition of pinnipeds using an unmanned aerial system PLOS ONE 12 11 e0187465 Bibcode 2017PLoSO 1287465K doi 10 1371 journal pone 0187465 PMC 5706667 PMID 29186134 a b Krause Douglas J Goebel Michael E Marshall Greg J Abernathy Kyler 2016 02 24 Summer diving and haul out behavior of leopard seals Hydrurga leptonyx near mesopredator breeding colonies at Livingston Island Antarctic Peninsula Marine Mammal Science 32 3 839 867 doi 10 1111 mms 12309 ISSN 0824 0469 Respiration and Diving Physiology PDF Cetus UCSD Muir Shona F Barnes David K A Reid Keith 2006 Interactions between humans and leopard seals Antarctic Science 18 1 61 74 Bibcode 2006AntSc 18 61M doi 10 1017 S0954102006000058 S2CID 53648359 a b c d Owen James August 6 2003 Leopard Seal Kills Scientist in Antarctica National Geographic Society Retrieved 2007 12 10 a b c Carrington Damian 2003 07 24 Inquiry into fatal leopard seal attack begins NewScientist com Retrieved on 2013 02 24 Shackleton Ernest 1998 South New York NY The Lyons Press p 112 ISBN 1 55821 783 5 NSRI appeal to the public to be cautious around seals and sea animals in general National Sea Rescue Institute Retrieved 1 October 2021 Gyford Sue 2003 11 14 1 ecophotoexplorers com Retrieved on 2019 08 20 Briggs Mike Briggs Peggy 2005 The Encyclopedia of World Wildlife Parragon p 60 ISBN 978 1 40545 680 7 National Geographic photographer s surprise encounter with deadly predator dpreview com 2012 10 18 Leopard Seal Seal Facts and Information www seals world com Retrieved 2018 04 18 General references EditRogers Tracey L 2009 The leopard seal Hydrurga leptonyx In Perrin W F Wursig B Thewissen J G M eds Encyclopedia of Marine Mammals 2nd ed Academic Press ISBN 978 0 12 373553 9 Heacox Kim 2006 Deadly Beauty National Geographic November 2006 Saundry Peter 2010 Leopard Seal Encyclopedia of Earth Topic ed C Michael Hogan editor in chief Cutler Cleveland NCSE Washington DCExternal links Edit Marine life portal Mammals portal Wikimedia Commons has media related to Leopard Seal Wikispecies has information related to Hydrurga leptonyx Wikisource has the text of the 1905 New International Encyclopedia article Sea leopard Best Wildlife Photos of 2005 Underwater World Winner Leopard Seal Pass Face off with a deadly predator video National Geographic photo assignment Voices in the Sea the Leopard Seal audio Retrieved from https en wikipedia org w index php title Leopard seal amp oldid 1133369335, wikipedia, wiki, book, books, library,

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