Seal Skull: Band 04 Blue/Band 16 Sapphire (Collins Big Cat Progress)

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Monk seals and elephant seals were previously believed to have first entered the Pacific through the open straits between North and South America, [5] with the Antarctic true seals either using the same route or travelled down the west coast of Africa. [6] It is now thought that the monk seals, elephant seals, and Antarctic seals all evolved in the southern hemisphere, and likely dispersed to their current distributions from more southern latitudes. [7] Taxonomy [ edit ] Pinnipedia Bjørge, A.; Øien, N.; Hartvedt, S.; Bøthum, G.; Bekkby, T. (2002). "Dispersal and bycatch mortality in grey, Halichoerus grypys, and harbour, Phoca vitulina, seals tagged at the Norwegian coast". Mar. Mammal Sci. 18 (4): 963–976. doi: 10.1111/j.1748-7692.2002.tb01085.x. S2CID 84812505. Our landmark morphometric analysis showed that the shape variation in the fossil seal skulls is greater than any single extant seal species. It also suggested that three skulls formed an ontogenetic, or growth, series. The anatomical and quantitative analyses suggested that there were two or three seal species present at Langebaanweg.

While many pinnipeds will feed on several types of prey, some are specialized feeders, preferring one type of prey. The crabeater seal does not eat crabs like its name suggests but rather feeds on krill. This seal evolved specialized teeth with grooves that act like a sieve and filter the krill from the surrounding water. Off the coast of Antarctica, the leopard seal is a formidable predator. It is a known penguin hunter, and will snag the birds with its canines and thrash them against the water’s surface. Leopard seals have been known to occasionally hunt other seals too. Walruses became a sought-after animal for zoos in the early 1900s, but it wasn’t until after WWI that zoos were able to care for them effectively. Most walruses only lived a few years before they succumbed to pneumonia or an ailment tied to malnourishment. In 1949, a walrus at the Copenhagen Zoo named Gine became the longest living walrus in captivity. She lived for 11 years and 10 months. It wasn’t until the 1960s that zoos had the knowledge and ability to supply proper nourishment to walruses and allow them to grow properly. Even today, there are few walruses held in captivity. This latest study was conducted using 3D landmark morphometrics. This process identifies landmarks on the fossil and the distances between them are measured. Once these are calculated it is possible to see the shape of the skull in relation to other seal skulls. Elephant seals have a reputation for randomly ending up in unexpected places. Because seals are mammals, they don’t have gills to filter oxygen from water. This means it’s easier for them to transition from marine water to freshwater. Sometimes a seal will swim up a river and just stay put. The 1000-year-old elephant seal suggests that this fluke behavior has been happening for a long time.

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. We showed that the age at which the shape of the skull stopped changing was 7 years in the spotted seal and 7 years in the harbor seal. Using all 75 landmarks, 54 individuals (25 spotted seals, 29 harbor seals) that were older than the age at which the skull stopped changing were correctly identified at an accuracy of 100%. Since each average position of landmarks on harbor seals was more on the lateral than on spotted seals (Figure 4), the skull of the harbor seal is broader and larger than that of the spotted seal. Burns( 2002) and Nakagawa et al.( 2009) reported that the skull of the harbor seal was more massive and robust than that of the spotted seal, a finding that was also supported by the present study. Perrin, William F.; Würsig, Bernd; Thewissen, J.G.M. (2009). Encyclopedia of Marine Mammals. Academic Press. ISBN 978-0-08-091993-5. NSRI appeal to the public to be cautious around seals and sea animals in general". National Sea Rescue Institute . Retrieved 1 October 2021.

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 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. Analysis of the seal relationships showed that the Langebaanweg seals are grouped together with the Antarctic phocid seals. They are closely related to the Antartic’s Ross seal. The leopard seal has a distinctively long and muscular body shape when compared to other seals. The overall length of adults is 2.4–3.5m (7.9–11.5ft) and weight is from 200 to 600 kilograms (440 to 1,320lb) making them the same length as the northern walrus but usually less than half the weight. [7] [8] Females are slightly larger than males. [9] 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.

Ecology and Behavior

Climate may also change the types of food available to pinnipeds. Galapagos sea lions historically ate sardines as the main source of their diet. But as climate change has gradually warmed the region, these fish have become scarce. During El Nino years when the water is particularly warm, up to 100 percent of newborn pups and up to 50 percent of yearlings die due to starvation. As a result, over the last 30 years the Galapagos sea lion population has shrunk from 40,000 individuals to fewer than 15,000. Without an abundant source of sardines, sea lions have had to get creative when it comes to finding food. In recent years they have been observed working in teams to corral and catch yellowfin tuna. Tuna swim about twice as fast as sea lions and so the sea lions have learned to use the maze-like shoreline to trap the fish. The entire endeavor takes time and energy, but when successfully executed, a 50-pound meal is quite the reward. Rule, James P.; Adams, Justin W.; Marx, Felix G.; Evans, Alistair R.; Tennyson, Alan J. D.; Scofield, R. Paul; Fitzgerald, Erich M. G. (2020-11-11). "First monk seal from the Southern Hemisphere rewrites the evolutionary history of true seals". Proceedings of the Royal Society B: Biological Sciences. 287 (1938): 20202318. doi: 10.1098/rspb.2020.2318. PMC 7735288. PMID 33171079. Burnie, David; Wilson, Don E. (2001). Animal. New York City: DK Publishing. ISBN 978-0-7894-7764-4. One park ranger in New York City, which is dead center of its West Atlantic range, says that "New York is like their Miami resort." [31] This refers to the habit of young seals leaving Cape Cod and even some Arctic waters to inhabit the harbor in winter. In 2018 the New York Post reported that the harbor is now "cleaner than it has been in 110 years," [35] and since the first decade of the 21st century, the harbor seal has found the old turf of its ancestors to be a land of plenty and the water to be livable. Within sight of the New York skyline, known colonies of harbor seals are found on Hoffman [36] and Swinburne Islands [37] as well as portions of Red Hook [38] and Staten Island, [39] readily hauling out every from October until very early May. Known favorite foods of the seal are returning in grand numbers to New York Harbor as well as nearby New Jersey, from Raritan Bay all the way down the entire Jersey Shore, with schools of mossbunker regularly attracting harbor seals, their cousins the grey seals, dolphins and, most recently, whales. [40] Both the northern and southern shores of Long Island have a reliable population of harbor seals as well as greys, where they will take sand lance as well as some species of crab as part of their diet. Dewaele, Leonard; Lambert, Olivier; Louwye, Stephen (2017-02-21). "On Prophoca and Leptophoca (Pinnipedia, Phocidae) from the Miocene of the North Atlantic realm: redescription, phylogenetic affinities and paleobiogeographic implications". PeerJ. 5: e3024. doi: 10.7717/peerj.3024. PMC 5322758. PMID 28243538.

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 Grey Seal ( Halichoerus grypus) poses in the waters off Acadia National Park in Maine. (Brian Skerry, National Geographic) Life at sea requires a powerful and streamlined body. Pinnipeds have adapted sleek, torpedo-shaped bodies that can cut through the water without producing significant drag. They’ve also developed powerful flippers to propel and steer themselves through the water. Unlike whales and dolphins, sea lions have extremely flexible bodies, and can almost bend their bodies in half. Anatomy Propulsion and Movement 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.

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To learn more about the specimen, Valenzuela-Toro, Zicos and Pyenson had to rely solely on morphology — the study of an animal’s physical characteristics to determine its species. They did so by comparing the cast of the skull to more recent specimens in the marine mammals collection. Comparisons of the mean for each landmark between spotted seal (circle) and harbor seal (triangle) (a) Dorsal view of the cranium; (b) Ventral view of the cranium; (c) Lateral view of the cranium; (d) Lateral view of the mandible). Asterisk (*) indicates the centroid point in each view. Outline of the skull are fitted to landmarks of the spotted seal (circle) to compare with the harbor seal (triangle). Each number indicates the landmark. Solid circles, triangles, and red number show important landmarks for discrimination Hoover, also rescued from a Maine harbor. Hoover became famous for his ability to imitate human speech, something not observed in any other mammal.

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 How to safely spot sea lions and seals along the Southern California coast". Scpr.org. August 22, 2011. Around the sub-Antarctic island of South Georgia, the Antarctic fur seal ( Arctocephalus gazella) is the main prey. Antarctic krill, southern elephant seal pups and petrels such as the diving petrel and the cape petrel have also been taken as prey. [35] Vagrant leopard seals in New Zealand have been observed predating on chondrichthyans; elephantfish, ghost sharks, and spiny dogfish were recorded as prey items. Additionally, this population of leopard seals and those in Australia were noted to bear wounds from chimaeriforms and stingrays respectively. [36] a b c d e Härkönen, T.; Heide-Jørgensen, M.-P. (1990-12-01). "Comparative life histories of East Atlantic and other harbour seal populations". Ophelia. 32 (3): 211–235. doi: 10.1080/00785236.1990.10422032. ISSN 0078-5326.Sea level rise could also greatly endanger pinnipeds, especially those in warmer waters. Hawaiian monk seals, for example, rely heavily on the atolls of the Northwest Hawaiian Islands, some of which only rise a few feet above current sea level and may become completely submerged if sea levels continue to rise. In the Mediterranean, monk seals inhabit coastal caves that may become increasingly flooded with rising sea levels. Captivity a b c d e f g "Leopard seal | TravelWild Expeditions". TravelWild Expeditions . Retrieved 2018-04-18. 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.