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Seals can conserve oxygen for long period of time underwater. When the seal starts diving its heart rate slows to about one-tenth of the normal rate. The harbor (or harbour) seal ( Phoca vitulina), also known as the common seal, is a true seal found along temperate and Arctic marine coastlines of the Northern Hemisphere. The most widely distributed species of pinniped (walruses, eared seals, and true seals), they are found in coastal waters of the northern Atlantic and Pacific oceans, Baltic and North seas.
The upper right canine teeth were taken from each skull, sectioned at 10μm with a cryostat (Leica Biosystems), and stained with Delafield's hematoxylin, following fundamental methods (Hachiya & Ohtaishi, 1994; Hohn, 2002) to determine the age. Ages were estimated based on the counts of cementum annuli (Mansfield & Fisher, 1960). 2.2 Preprocessing 2.2.1 Photography of skulls Reproduction [ edit ] Southern elephant seals in Argentina Living only in Lake Saimaa, Finland, Saimaa ringed seals, a subspecies of ringed seal, are among the most endangered seals in the world, having a total population of only about 400 individuals. [18] Male northern elephant seals face off for the best beach territory for mating season. (Robert Schwemmer, CINMS, NOAA) Southern elephant seals normally live in the South Atlantic, often as far south as Antarctica. These are young male Southern elephant seals from the South Shetland and Anvers islands, Antarctica. (Daniel Costa / University of California, Santa Cruz under the National Marine Fisheries Service permits (numbers 87-1593 and 87-1851-00) and ACA authorization) Tunstall, T. "Hydrurga leptonyx". Animal Diversity Web. University of Michigan Museum of Zoology . Retrieved 2009-04-27.Considerable scientific inquiry has been carried out by the Marine Mammal Center and other research organizations beginning in the 1980s regarding the incidence and transmission of diseases in harbor seals in the wild, including analysis of phocine herpesvirus. [28] In San Francisco Bay, some harbor seals are fully or partially reddish in color, possibly caused by an accumulation of trace elements such as iron or selenium in the ocean, or a change in the hair follicles. [29] Phocid seals lifestyle is independent of land suggesting that island hopping was a possible way that South Africa’s west coast was colonised. The nutrient rich Benguela Upwelling System was established off the coast by this time resulting in an increased food supply. Seals would have used the Antarctic circumpolar current and the South Atlantic current to colonise islands in the Southern Ocean, then colonise islands off South Africa’s coast.
Our shared future with other species is about what just happened in a very tangible way and there’s nothing more tangible than having a museum record,” said Pyenson. Saundry, Peter. (2010) Leopard Seal. Encyclopedia of Earth. Topic ed. C. Michael Hogan, editor-in-chief Cutler Cleveland, NCSE, Washington DCa 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. The earliest known fossil earless seal is Noriphoca gaudini from the late Oligocene or earliest Miocene ( Aquitanian) of Italy. [1] Other early fossil phocids date from the mid-Miocene, 15 million years ago in the north Atlantic. [1] [3] Until recently, many researchers believed that phocids evolved separately from otariids and odobenids; and that they evolved from otter-like animals, such as Potamotherium, which inhabited European freshwater lakes. Recent evidence strongly suggests a monophyletic origin for all pinnipeds from a single ancestor, possibly Enaliarctos, most closely related to the mustelids and bears. [4]
Taylor, Margot (2017-09-27). "Odds against St Kilda leopard seal pup". Otago Daily Times . Retrieved 2020-07-25. Wilson, Don E.; Seeder, Dee Ann M., eds. (2005). "Species: Hydrurga leptonyx". Mammal species of the world: a taxonomic and geographic reference (3rded.). Baltimore: Johns Hopkins University Press. ISBN 978-0-8018-8221-0. 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] Although some of the largest harbor seal pupping areas are found in California, they are also found north along the Pacific Coast in Oregon, Washington, British Columbia and Alaska. Large populations move with the season south along the west coast of Canada and may winter on the islands in Washington and Oregon. Pupping is known to occur in both Washington and Oregon as of 2020. People are advised to stay at least 50m away from harbor seals that have hauled out on land, especially the pups, as mothers will abandon them if there's too much human activity nearby. [30] A Harbor Seal nursery on ice in front of The Grand Pacific Glacier in Glacier Bay National Park, Alaska Atlantic Coast [ edit ] Connie's interest in bones on beaches grew as she found dead seals and dolphins out on her dog walks. Initially reporting them, and eventually volunteering for Cornwall Wildlife Trust's Marine Strandings Network and recording them herself, she realised that many people could not recognise certain marine animals from their skeletons.
a b c d Owen, James (August 6, 2003). "Leopard Seal Kills Scientist in Antarctica". National Geographic Society. Archived from the original on August 8, 2003 . Retrieved 2007-12-10. 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. Pinnipeds need to see both above and below the sea surface, a slight dilemma since good eyesight in either location requires very different adaptations. Terrestrial animals, including humans, rely on the cornea—the clear outer layer of the eye—to focus images using a property called refraction, a bending of light as it crosses through different materials. As light travels through the air and enters the eye, it bends to the appropriate angle and creates a focused image on the retina. Underwater, terrestrial animals become farsighted because the fluid of the eye and the water are too similar, the light doesn’t bend enough so the image doesn’t focus effectively. Pinnipeds solve this issue with an especially round fisheye lens that refracts light appropriately underwater. Humans, on the other hand, have a flat lens. Studies of the fossils have provided a detailed understanding of the terrestrial fauna and flora along the west coast of South Africa. Shedding new light A total of eight identification landmarks (15, 28, 34, 35, 56, 70, 72, 73) were narrowed down while maintaining the same discrimination ratio (100%) among the total number of 75 landmarks. Of the eight landmarks, seven were related to the feeding apparatus (15, 28, 34, 35, 70, 72, 73). Differences in landmarks 15, 28, 34 and 35 indicated that the harbor seal has a longer rostrum and broader palate than the spotted seal. Slater et al.( 2009) reported that a broader rostrum would enable to have a larger and stronger bite, and the longer, broader rostrum of the harbor seal would therefore enable it to open its mouth wider and have a stronger bite than the spotted seal. Differences in position of landmark 70 (angular process) was indicated that the harbor seal has a more developed angular process relative to the spotted seal (Figure 4). The angular process serves for the attachment of the pterygoids medially and the masseter laterally (Evans & de Lahunta, 2013). Expansion of the angular process reflect increased size of the masseter musculature (Radinsky, 1985). Therefore, this suggests that the harbor seal may have larger masseter musculature and stronger bite force. Differences in the position of landmarks 72 and 73 indicated that the mandible of the harbor seal was broader than that of the spotted seal. Differences in position of landmark 73 indicated that the body of the mandible around landmark 73 was more angular than the spotted seal. Those positions (72, 73) relate to area of attachment for the digastric muscle, which helps with opening the mouth. The broader of the body of the mandible under the row of teeth and the more ventral position of the 73 seems to support the attachment of much digastric muscle that could be developed for strong biting movement. Although bite performance is generally related to the type of prey, both species are dietary generalists and are classified as pierce feeders (Adam & Berta, 2002) and thus do not need to crush hard prey. Euphausiids are the prey of newly weaned spotted seal pups (Kato, 1982) and schooling fishes are the main prey of older seals (Kobayashi, 2015). On the other hand, harbor seals are opportunistic feeders on locally abundant and easily available prey items (Telmann & Galatius, 2018), and they have been found to prefer foraging demersal fishes in shallow waters and also cephalopod species (Andersen et al., 2004; Bromaghin et al., 2013; Nakaoka et al., 1986). Additionally, a comparative study of the feeding habitats of spotted seals and harbor seals in the same coastal area in the Nemuro district of eastern Hokkaido, Japan, for example, demonstrated that the harbor seal depends on benthic animals in shallow waters, while the spotted seal foraged for prey from the surface to middle layers (Nakaoka et al., 1986). However, a variety of common prey was also found in spotted seals and harbor seals stomachs (Nakaoka et al., 1986), suggesting that the harbor seal could not necessarily need a longer mouth and stronger bite than the spotted seal. Also, information on the stomach contents may vary temporary, therefore
By comparing the cast with other specimens from different species, they determined that it represented a male Southern elephant seal. It also had some marks that suggest it may have been butchered by Indigenous people after being found. It seemed unlikely that a complete skull was traded from South America to North America, according to the team. Instead, they argued that the seal likely strayed off its annual migration pattern and swam to Indiana by accident. That explanation aligned with behaviors other scientists have observed seals doing today. Berta, Annalisa (2009). "Pinnipedia: Overview". In Perrin, W. F.; Würsig, B.; Thewissen, J. G. M. (eds.). Encyclopedia of Marine Mammals (2nded.). Academic Press. pp. 878–85. ISBN 978-0-12-373553-9. 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.Though able to move on both land and sea, pinnipeds are the most efficient underwater. Some species spend the majority of their life in the ocean—female northern elephant seals spend 66 percent of their time in the open ocean.
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