Editing Pinniped (section)

===Senses===
[[File:Reflection in a seal eye.jpg|thumb|right|Light reflection on an elephant seal eye]]
The eyes of pinnipeds are relatively large for their size and are positioned near the front of the head. Only the smaller eyes of the walruses are located on each side of the head;{{sfn|Riedman|1990|p=43}}{{sfn|Berta|2012|pp=67}} since they forage at the bottom for [[Sedentary lifestyle|sedentary]] mollusks.{{sfn|Riedman|1990|p=43}} A seal's eye is suited for seeing both underwater and in air. Most of [[retina]] is [[equidistant]] around the spherical [[lens (anatomy)|lens]]. The [[cornea]] has a flattened center where [[refraction]] does not change between air and water. The vascular [[iris (anatomy)|iris]] has a strong [[Iris dilator muscle|dilator muscle]]. A [[Miosis|contracted]] pupil is typically pear-shaped, although the [[bearded seal]]'s is more horizontal. Compared to deep-diving elephant seals, the iris of shallower species, such as [[harbor seal]]s and California sea lions, does not change much in size between contraction and [[Mydriasis|expansion]].<ref>{{Cite journal |author1=Mass, A. M. |author2=Supin, A. Y. |doi=10.1002/ar.20529 |pmid=17516421 |title=Adaptive features of aquatic mammals' eye |journal=The Anatomical Record |volume=290 |issue=6 |pages=701–15 |year=2007 |s2cid=39925190 |doi-access=free }}</ref> Seals are able to see in relative darkness with a ''[[tapetum lucidum]]'', a reflecting layer that increases sensitivity by reflecting light back through the [[Rod cells|rods]].{{sfn|Riedman|1990|p=45}} 
[[File:Fur Seal at Cape Cross, Namibia (3045707919).jpg|thumb|left|Frontal view of [[brown fur seal]] head]]
On land, pinnipeds are [[Myopia|near-sighted]] in dim light. This is reduced in bright light as the contracted pupil decreases the ability of the lens and the cornea to refract (bend) light.{{sfn|Riedman|1990|p=46}} Polar living seals like the harp seal have corneas that can withstand the bright light that reflects off snow and ice, which would otherwise cause [[snow blindness]].<ref>Lavigne, D. M. "Harp seal" in {{harvnb|Perrin|Würsig|Thewissen|2009|pp=542–546}}</ref>{{sfn|Riedman|1990|p=46}} Color vision requires at least two types of visual pigments with different spectral sensitivities but since pinnipeds lack short-wavelength-sensitive [[cone cell]]s, they are generally considered to be color-blind.<ref>{{cite book|last1=Davis|first1=Randall W.|title=Marine mammals. Adaptations for an aquatic life|publisher=Springer|year=2019|ISBN=978-3-319-98278-6|page=182|chapter=Sensory Systems}}</ref> Flexible eye movement has been documented in seals.<ref>{{Cite journal |author1=Hanke, F. D. |author2=Hanke, W. |author3=Scholtyssek, C. |author4=Dehnhardt, G. |title=Basic mechanisms in pinniped vision |doi=10.1007/s00221-009-1793-6 |journal=Experimental Brain Research |volume=199 |issue=3–4 |pages=299–311 |year=2009 |pmid=19396435|s2cid=23704640 }}</ref> The walrus can project its eyes out from its sockets in both a forward and upward direction due to its advanced [[extraocular muscles]] and absence of an orbital roof.<ref name=Kastelein>Kastelein, R. A. "Walrus" in {{harvnb|Perrin|Würsig|Thewissen|2009|pp=1212–1216}}</ref> The seal eye is durable as the [[corneal epithelium]] is hardened by [[keratin]], and the [[sclera]] is thick enough to withstand the pressures of diving. Seals also secrete [[mucus]] from the [[lacrimal gland]] to protect their eyes. As in many mammals and birds, pinnipeds possess [[nictitating membrane]]s.{{sfn|Riedman|1990|pp=3, 49}}

The pinniped ear is adapted for hearing underwater, where it can hear sound frequencies of up to 70,000&nbsp;[[hertz|Hz]]. In air, hearing is somewhat reduced in pinnipeds compared to many terrestrial mammals. While their airborne hearing sensitivity is generally weaker than humans', they still have a wide frequency range.{{sfn|Riedman|1990|p=39}} One study of three species—the harbor seal, California sea lion and [[northern elephant seal]]—found that the sea lion was best adapted for airborne hearing, the elephant seal for underwater hearing and the harbor seal was equally adapted for both.<ref>{{Cite journal |author1=Kastak, D. |author2=Schusterman, R. J. |title=Low-frequency amphibious hearing in pinnipeds: Methods, measurements, noise, and ecology |doi=10.1121/1.421367 |journal=The Journal of the Acoustical Society of America |volume=103 |issue=4 |pages=2216–2228 |year=1998 |pmid=9566340|bibcode=1998ASAJ..103.2216K }}</ref> Although pinnipeds have a fairly good sense of smell on land,<ref>{{Cite journal |author1=Kowalewsky, S. |author2=Dambach, M. |author3=Mauck, B. |author4=Dehnhardt, G. |title=High olfactory sensitivity for dimethyl sulphide in harbour seals |doi=10.1098/rsbl.2005.0380 |journal=Biology Letters |volume=2 |issue=1 |pages=106–09 |year=2006 |pmid=17148339 |pmc=1617201}}</ref> it is useless under water as their nostrils are closed.{{sfn|Riedman|1990|p=40}}
[[File:Walrus - Kamogawa Seaworld - 1.jpg|thumb|right|[[Vibrissa]]e of walrus|alt=Photo of walrus head in profile showing one eye, nose, tusks, and "mustache"]]
The [[whiskers]] or [[vibrissa]] are normally smooth in otariids and walruses, while those of most phocids are wavey.<ref>{{cite journal|last1=Morgenthal|first1=K|last2=Krüger|first2=Y|last3=Rogers|first3=T|last4=Dehnhardt|first4=G|last5=Hanke|first5=F. D.|year=2025|title=Characterization of pinniped vibrissal type and number|journal=Marine Mammal Science|volume=41|issue=1|page=e13166|doi=10.1111/mms.13166|doi-access=free}}</ref> The whiskers of some otariids grow quite long—those of the [[Antarctic fur seal]] can reach {{convert|41|cm|in|abbr=on}}–<ref>{{cite book|author=Renouf, D.|editor-last=Renouf, D.|year=1991|chapter=Sensory reception and processing in Phocidae and Otariidae|title=Behaviour of Pinnipeds |publisher=Chapman and Hall |page=373|isbn=978-0-412-30540-5}}</ref> while Walruses have the most vibrissae, at 600–700&nbsp;individual hairs.{{sfn|Riedman|1990|p=42}} Compared to terrestrial mammals, the vibrissae of pinnipeds have ten times more nerve connections, allowing them to effectively detect vibrations in the water.<ref>{{cite journal |last1=Schusterman |first1=R. J. |last2=Kastak |first2=D. |last3=Levenson |first3=D. H. |last4=Reichmuth |first4=C. J. |last5=Southall |first5=B. L. |title=Why pinnipeds don't echolocate |doi=10.1121/1.428506 |journal=The Journal of the Acoustical Society of America |volume=107 |issue=4 |pages=2256–64 |year=2000 |pmid=10790051|bibcode=2000ASAJ..107.2256S |doi-access=free }}</ref> These vibrations are generated, for example, when a fish swims through water. Detecting vibrations is useful when the animals are foraging, and may add to or even replace vision, particularly in darkness.<ref name=whiskers>{{cite journal |last1=Miersch |first1=L. |last2=Hanke |first2=W. |last3=Wieskotten |first3=S. |last4=Hanke |first4=F. D. |last5=Oeffner |first5= J. |last6=Leder |first6=A. |last7=Brede |first7= M. |last8=Witte |first8=M. |last9=Dehnhardt |first9=G. |doi=10.1098/rstb.2011.0155 |title=Flow sensing by pinniped whiskers |journal=Philosophical Transactions of the Royal Society B: Biological Sciences |volume=366 |issue=1581 |pages=3077–84 |year=2011 |pmid=21969689 |pmc=3172597}}</ref><ref name=blindseals>{{Cite journal |author=Hyvärinen H. |doi=10.1111/j.1469-7998.1989.tb05008.x |title=Diving in darkness: whiskers as sense organs of the ringed seal (Phoca hispida saimensis) |journal=Journal of Zoology |volume=218 |issue=4 |pages=663–678 |year=1989}}</ref> 

Harbor seals can follow hydrodynamic paths made minutes earlier, similar to a dog following a scent trail,<ref name=dehnhardt>{{cite journal |title=Hydrodynamic trail-following in harbor seals (Phoca vitulina) |journal=Science |volume=293 |issue=5527 |pages=102–104 |doi=10.1126/science.1060514 | year=2001 | last1=Dehnhardt | first1=G. | pmid=11441183|s2cid=9156299 }}</ref><ref name=schulte-pelkum>{{cite journal | title=Tracking of biogenic hydrodynamic trails in harbour seals (Phoca vitulina) |journal=Journal of Experimental Biology |volume= 210 |issue=Pt 5 |pages=781–787 |year=2007 |doi=10.1242/jeb.02708 | pmid=17297138 |vauthors=Schulte-Pelkum N, Wieskotten S, Hanke W, Dehnhardt G, Mauck B |doi-access=free }}</ref> and can even discriminate the size and type of object responsible for the trail.<ref name=sealdiscrim>{{Cite journal |vauthors=Grant R, Wieskotten S, Wengst N, Prescott T, Dehnhardt G |title= Vibrissal touch sensing in the harbor seal (Phoca vitulina): how do seals judge size? |journal=Journal of Comparative Physiology A |volume=199 |issue= 6 |pages=521–531 |year=2013 |doi=10.1007/s00359-013-0797-7|pmid= 23397461 |s2cid= 14018274 }}</ref> Unlike terrestrial mammals, such as [[rodents]], pinnipeds do not sweep their whiskers over an object when examining it, but can protract the hairs forward while holding them steady, maximizing their detection.<ref name=whiskers/><ref name=angle>{{Cite journal |author1=Murphy, T.C. |author2=Eberhardt, W.C. |author3=Calhoun, B.H. |author4=Mann, K.A. |author5=Mann, D.A. |doi=10.1371/journal.pone.0069872 |pmid=23922834 |title=Effect of Angle on Flow-Induced Vibrations of Pinniped Vibrissae |journal=PLOS ONE |volume=8 |issue=7 |page=e69872 |year=2013 |pmc=3724740|bibcode=2013PLoSO...869872M |doi-access=free }}</ref> The vibrissa's angle relative to the flow seems to be the most important contributor to detection ability.<ref name=angle /> Whiskers may also play a role in navigation; [[spotted seal]]s appear to use them to detect breathing holes in the ice.{{sfn|Riedman|1990|p=42}}