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

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For species living in the extreme cold, fur adds an additional layer of warmth. Fur seals rely on two layers of fur, an outer protective layer and an underfur that traps air bubbles and insulates the skin—the seals have roughly 300,000 underfur hairs per square inch. Baby harp seals have an extra defense to keep warm—their snow-white fur helps absorb heat from the sun.

About a month after males come ashore the females begin to arrive. They congregate in the male territories in groups called harems. Many are pregnant from the last year’s mating season and within a few days they give birth. The next few days are dedicated to bonding—mom and pup learn to recognize one another’s unique smell and voice, a necessity for the coming months when mom will leave to find food in the ocean. Upon her return they will need to reunite within the chaos of the rookery, and both smell and vocalizations help them do so. a b McLaren, Ian (1984). Macdonald, D. (ed.). The Encyclopedia of Mammals. New York: Facts on File. pp. 270–275. ISBN 978-0-87196-871-5.Scheel, Dirk-Martin; Slater, Graham J.; Kolokotronis, Sergios-Orestis; Potter, Charles W.; Rotstein, David S.; Tsangaras, Kyriakos; Greenwood, Alex D.; Helgen, Kristofer M. (2014). "Biogeography and taxonomy of extinct and endangered monk seals illuminated by ancient DNA and skull morphology". ZooKeys (409): 1–33. doi: 10.3897/zookeys.409.6244. PMC 4042687. PMID 24899841. 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. In the 1980s and 1990s, morphological phylogenetic analysis of the phocids led to new conclusions about the interrelatedness of the various genera. More recent molecular phylogenetic analyses have confirmed the monophyly of the two phocid subfamilies ( Phocinae and Monachinae). [9] [10] [11] [5] The Monachinae (known as the "southern" seals), is composed of three tribes; the Lobodontini, Miroungini, and Monachini. The four Antarctic genera Hydrurga, Leptonychotes, Lobodon, and Ommatophoca are part of the tribe Lobodontini. Tribe Miroungini is composed of the elephant seals. The Monk seals ( Monachus and Neomonachus) are all part of the tribe Monachini. [12] Likewise, subfamily Phocinae (the "northern" seals) also includes three tribes; Erignathini ( Erignathus), Cystophorini ( Cystophora), and Phocini (all other phocines). More recently, five species have been split off from Phoca, forming three additional genera. [13] 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.

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 Mating season means different things for different pinniped species. For some, it means hauling out of the sea in massive rookeries on shore, while for others it can mean finding a sturdy ice floe. Landmarks 15, 34, and 35 (on the orbit and pterygoid hamular) in harbor seals were at the more posterior location than those of the spotted seals (Figure 4a, b). Landmark 28 (molar) in harbor seals was located more on the buccal compared with the spotted seals (Figure 4b). 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.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] 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 After females mate the next few months are dedicated to fattening the pups. In some species, mom will spend several days at sea foraging for food and then returning to feed her pup with milk. In other species, mom lives off her fat reserves and stays with her pup continuously until it is weaned. After a few months, the two return to the ocean and the pup learns how to forage for itself. 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. Habitat and diet [ edit ] Harbor seals at Point Lobos, California Harbor seal in the freshwater Connecticut River, following the shad run

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. Newby, T.C. (1978). Pacific Harbor Seal pp 184–191 in D. Haley, ed. Marine Mammals of Eastern North Pacific and Arctic Waters, Pacific Search Press, Seattle WA. 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. Wilson, Don E.; Reeder, DeeAnn M., eds. (2005). "Family: Phocidae". Mammal species of the world: a taxonomic and geographic reference (3rded.). Baltimore: Johns Hopkins University Press. ISBN 978-0-8018-8221-0.

What are the differences between a bone and a fossil?

Nowak, Ronald M (2003). Walker's Marine Mammals of the World. Johns Hopkins University Press: Baltimore, MD. a b "Marine Species Identification Portal: Leopard seal - Hydrurga leptonyx". species-identification.org . Retrieved 2018-03-19. Popeye, the official seal of Friday Harbor, Washington, notable for her common sightings up until 2019, when she was presumed to have died. She was identified and named for her cloudy left eye. There is a statue of her in the Port of Friday Harbor. 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]

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. Male northern elephant seals face off for the best beach territory for mating season. (Robert Schwemmer, CINMS, NOAA) 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. A Vision for Menhaden: Supporting Anglers, Wildlife, and Businesses From Florida to Maine". Pew.org . Retrieved 2020-10-06. Berta, A.; Churchill, M. (2012). "Pinniped Taxonomy: evidence for species and subspecies". Mammal Review. 42 (3): 207–234. doi: 10.1111/j.1365-2907.2011.00193.x.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. 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.