Editing Dolphin (section)

===Senses===
[[File:Delfinekko.gif|thumb|[[Biosonar]] by cetaceans]]
[[File:Toothed whale sound production.svg|upright=1.35|Diagram illustrating sound generation, propagation, and reception in a toothed whale. Outgoing sounds are in cyan and incoming ones are in green]]

A dolphin ear has specific adaptations to the [[Marine (ocean)|marine]] environment. In humans, the [[middle ear]] works as an impedance equalizer between the outside air's low [[Acoustic impedance|impedance]] and the [[cochlea]]r fluid's high impedance. In dolphins, and other marine mammals, there is no great difference between the outer and inner environments. Instead of sound passing through the outer ear to the middle ear, dolphins receive sound through the throat, from which it passes through a low-impedance fat-filled cavity to the inner ear. The ear is acoustically isolated from the skull by air-filled sinus pockets, which allow for greater directional hearing underwater.<ref>{{cite journal |author=Nummela, Sirpa |title=Sound transmission in archaic and modern whales: Anatomical adaptations for underwater hearing |journal=The Anatomical Record |volume=290 |issue=6 |pages=716–733 |year=2007 |doi=10.1002/ar.20528 |last2=Thewissen|first2=J.G.M |last3=Bajpai |first3=Sunil |last4=Hussain |first4=Taseer |last5=Kumar |first5=Kishor |pmid=17516434|s2cid=12140889 |url=http://repository.ias.ac.in/4651/1/321.pdf |author2-link=Hans Thewissen |doi-access=free }}<!--|access-date=August 29, 2015 --></ref> 

Dolphins generate sounds independently of respiration using recycled air that passes through air sacs and phonic (alternatively monkey) lips. Integral to the lips are oil-filled organs called dorsal bursae that have been suggested to be homologous to the sperm whale's spermaceti organ.<ref name="n010">{{cite journal |last1=Cranford |first1=Ted W. |last2=Amundin |first2=Mats |last3=Norris |first3=Kenneth S. |date=1996 |title=Functional morphology and homology in the odontocete nasal complex: Implications for sound generation |journal=Journal of Morphology |volume=228 |issue=3 |pages=223–285 |doi=10.1002/(SICI)1097-4687(199606)228:3<223::AID-JMOR1>3.0.CO;2-3 |pmid=8622183 |issn=0362-2525}}</ref> High-frequency clicks pass through the sound-modifying organs of the extramandibular fat body, intramandibular fat body and the [[melon (cetacean)|melon]]. This melon consists of fat, and the skull of any such creature containing a melon will have a large depression. This allows dolphins to use [[Animal echolocation|echolocation]] for orientation.<ref name="Cetacean anatomy" /><ref name="Dolphin senses">{{cite book |editor1=Thomas, Jeanette A. |editor2=Kastelein, Ronald A. |title=Sensory Abilities of Cetaceans: Laboratory and Field Evidence |volume=196 |isbn=978-1-4899-0860-5 |doi=10.1007/978-4899-0858-2 |year=2002 |url={{google books |plainurl=y |id=VWz1BwAAQBAJ}}|doi-broken-date=November 1, 2024 }}</ref><ref name="Thewissen-Hearing">{{cite book|editor-first1=William F. |editor-last1=Perrin|editor-first2=Bernd |editor-last2= Wursig|editor-first3=J.G.M. 'Hans' |editor-last3=[[Hans Thewissen|Thewissen]]|title=Encyclopedia of Marine Mammals|url={{google books |plainurl=y |id=2rkHQpToi9sC}}|date=February 26, 2009|publisher=Academic Press|isbn=978-0-08-091993-5}}</ref><ref>{{cite book |last=Ketten |first=Darlene R.|chapter=The Marine Mammal Ear: Specializations for Aquatic Audition and Echolocation |title=The Evolutionary Biology of Hearing |editor1-last=Webster |editor1-first=Douglas B. |editor2-last=Fay |editor2-first=Richard R. |editor3-last=Popper |editor3-first=Arthur N. |year=1992 |publisher=Springer |chapter-url=https://www.researchgate.net/publication/230691464 |access-date=March 1, 2013 |pages=725–727}}</ref><ref>{{Cite book
|title=A Proposed Echolocation Receptor for the Bottlenose Dolphin (''Tursiops truncatus''): Modelling the Receive Directivity from Tooth and Lower Jaw Geometry ''NATO ASI Series A: Sensory Abilities of Cetaceans'' |volume=196|pages=255–267
|location=NY
|publisher=Plenum
|year=1990
|isbn=978-0-306-43695-6
|editor1=Jeanette A. Thomas |editor2=Ronald A. Kastelein. }}</ref> Though most dolphins do not have hair, they do have [[hair follicle]]s that may perform some sensory function.<ref>{{cite journal
|title= Selective heating of vibrissal follicles in seals (''Phoca vitulina'') and dolphins (''Sotalia fluviatilis guianensis'')
|author1=Bjorn Mauck |author2=Ulf Eysel |author3=Guide Dehnhardt |journal=Journal of Experimental Biology |year=2000
|volume=203 |issue=14 |pages=2125–2131 |doi=10.1242/jeb.203.14.2125 |pmid=10862725 |bibcode=2000JExpB.203.2125M |url=http://jeb.biologists.org/cgi/reprint/203/14/2125.pdf
|access-date= March 11, 2007}}</ref> Beyond locating an object, [[Animal echolocation|echolocation]] also provides the animal with an idea on an object's shape and size, though how exactly this works is not yet understood.<ref>{{cite journal|last=Harley|first=Heidi E.|author2=DeLong, Caroline M.|title=Echoic Object Recognition by the Bottlenose Dolphin|journal=Comparative Cognition & Behavior Reviews|year=2008|volume=3|pages=45–65|doi=10.3819/ccbr.2008.30003|doi-access=free}}</ref> The small hairs on the rostrum of the [[boto]] (river dolphins of South America) are believed to function as a [[somatosensory system|tactile sense]], possibly to compensate for the boto's poor eyesight.<ref>{{cite web|title= Amazon River Dolphin (''Inia geoffrensis'')|first=Laurie|last=Stepanek|date=May 19, 1998|publisher=Texas Marine Mammal Stranding Network|url=http://www.tmmsn.org/mmgulf/inia_geoffrensis.html|access-date= November 20, 2013 |archive-url = https://web.archive.org/web/20070206051622/http://www.tmmsn.org/mmgulf/inia_geoffrensis.html |archive-date = February 6, 2007}}</ref>

A dolphin eye is relatively small for its size, yet they do retain a good degree of eyesight. As well as this, the eyes of a dolphin are placed on the sides of its head, so their vision consists of two fields, rather than a binocular view like humans have. When dolphins surface, their lens and cornea correct the nearsightedness that results from the water's refraction of light. Their eyes contain both [[rod cell|rod]] and [[cone cell|cone]] cells, meaning they can see in both dim and bright light, but they have far more rod cells than they do cone cells. They lack short wavelength sensitive visual pigments in their cone cells, indicating a more limited capacity for color vision than most mammals.<ref>{{cite journal |author1=Mass, Alla M. |author2=Supin, Alexander Y. A.  |title=Adaptive features of aquatic mammals' eyes |journal=Anatomical Record |volume=290 |issue=6 |pages=701–715 |date=May 21, 2007 |doi=10.1002/ar.20529 |pmid=17516421|s2cid=39925190 |doi-access=free }}</ref> Most dolphins have slightly flattened eyeballs, enlarged pupils (which shrink as they surface to prevent damage), slightly flattened corneas and a ''[[tapetum lucidum]]'' (eye tissue behind the retina); these adaptations allow for large amounts of light to pass through the eye and, therefore, a very clear image of the surrounding area. They also have glands on the eyelids and [[corneal epithelium|outer corneal layer]] that act as protection for the cornea.<ref name="Dolphin senses"/>

The [[olfactory lobes]] and [[olfactory nerve|nerve]] are absent in dolphins, suggesting that they have no sense of smell.<ref name="Dolphin senses"/>

Dolphins are not thought to have a good sense of taste, as their taste buds are atrophied or missing altogether. Some have preferences for different kinds of fish, indicating some ability to taste.<ref name="Dolphin senses"/>