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

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There are countless objects in the museum’s fossil marine mammals collection that represent a wide range of past animal behavior, distribution and anatomy. The Smithsonian’s collection of marine mammals currently includes over 15,000 fossils and casts of specimens from 50 million years ago to present day. Rogers, Tracey L. (2009). "The leopard seal, Hydrurga leptonyx". In Perrin, W. F.; Würsig, B.; Thewissen, J. G. M. (eds.). Encyclopedia of Marine Mammals (2nded.). Academic Press. ISBN 978-0-12-373553-9. Tunstall, T. "Hydrurga leptonyx". Animal Diversity Web. University of Michigan Museum of Zoology . Retrieved 2009-04-27. Allen, Sarah G. (1985). "Mating Behavior in the Harbor Seal". Marine Mammal Science. 1: 84–87. doi: 10.1111/j.1748-7692.1985.tb00532.x.

National Geographic photographer's surprise encounter with deadly predator. dpreview.com (2012-10-18)In comparison to many pinniped species, and in contrast to otariid pinnipeds, harbor seals are generally regarded to be more vocally reticent. However, they do utilize non-harmonic vocalizations to maintain breeding territories and to attract mates during specified times of year, [18] and also during mother and pup interactions. [19] 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". Centuries of human exploitation and habitat destruction have caused the remaining populations of Mediterranean monk seals ( Monachus monachus) and Hawaiian monk seals ( Monachus schauinslandi) to drop to perilously low numbers, while the Caribbean monk seal ( Monachus tropicalis) has become extinct. (MOm/ A.A. Karamanlidis) A Vision for Menhaden: Supporting Anglers, Wildlife, and Businesses From Florida to Maine". Pew.org . Retrieved 2020-10-06.

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. a b c d e f g "Leopard seal | TravelWild Expeditions". TravelWild Expeditions . Retrieved 2018-04-18. The earliest ancestors of seals and sea lions were mammals that transitioned from life on land to life at sea. Around 36 million years ago, at the end of the Oligocene, the ocean began to cool, which caused major changes to ocean circulation. This led to an increase in nutrients throughout the ocean and enabled ocean life to thrive. The pinniped’s ancestors were likely drawn to the ocean due to its abundance of food and over time they evolved to life in the water. Daniel Costa / University of California, Santa Cruz under the National Marine Fisheries Service permits (numbers 87-1593 and 87-1851-00) and ACA authorization

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Landmark 74 (ventral of the body of the mandible), which was reflected in PC1, and important identification landmarks 72 and 73 calculated by random forests were close to each other and showed tendencies similar to the selected landmark (Figures 4, 6). Landmark 29 (molar), which was reflected in PC2, and important identification landmark 28 calculated by random forests also showed a similar position at the posterior rostrum (Figures 4, 6). Landmark 56 (posterior of the external auditory meatus) of PC2 was also a common important identification landmark selected by random forests (Figures 4, 6). Landmarks 21–27 (anterior of the rostrum) and landmarks 8–10 and 12–13 (around the squamosal) were reflected in PCs in PCA, but these were not selected by the random forests (Figures 4, 6). 4 DISCUSSION 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. Studying the constantly growing collection can help researchers know more about what might happen in the future. 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.

Landmark 70 (angular process) in harbor seals was located more posteroventral compared with the spotted seals (Figure 4d). Landmarks 72 and 73 (ventral of the body of the mandible landmarks) in the harbor seal were located at an inferior position than in the spotted seal (Figure 4d). Landmark 73 was located at the most ventral position among the anterior on the mandible of the harbor seal (Figure 4d). Van Parijs, S.M.; Kovacs, K.M. (2002). "In-air and underwater vocalizations of eastern Canadian harbour seals, Phoca vitulina". Canadian Journal of Zoology. 80 (7): 1173–1179. doi: 10.1139/z02-088.

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. NSRI appeal to the public to be cautious around seals and sea animals in general". National Sea Rescue Institute . Retrieved 1 October 2021. Paterson, Ryan S.; Rybczynski, Natalia; Kohno, Naoki; Maddin, Hillary C. (2020). "A Total Evidence Phylogenetic Analysis of Pinniped Phylogeny and the Possibility of Parallel Evolution Within a Monophyletic Framework". Frontiers in Ecology and Evolution. 7. doi: 10.3389/fevo.2019.00457. The California population of subspecies P. v. richardsi amounted to about 25,000 individuals as of 1984. Pacific harbor seals or California harbor seals are found along the entire Pacific Coast shoreline of the state. They prefer to remain relatively close to shore in subtidal and intertidal zones, and have not been seen beyond the Channel Islands as a pelagic form; moreover, they often venture into bays and estuaries and even swim up coastal rivers. They feed in shallow littoral waters on herring, flounder, hake, anchovy, codfish, and sculpin. [21]