Editing Animal communication (section)

===Visual===
{{For|information on the perception of visual signals|Visual perception}}

;[[Gesture]]s: Most animals understand communication through a visual [[display (zoology)|display]] of distinctive body parts or bodily movements. Animals will reveal or accentuate a body part to relay certain information. The parent [[herring gull]] displays its bright yellow bill on the ground next over its chick when it has returned to the nest with food. The chicks exhibit a [[Begging behavior in animals|begging response]] by tapping the red spot on the lower mandible of the parent herring gull's bill. This signal stimulates the parent to regurgitate food and completes the feeding signal. The distinctive morphological feature accentuated in this communication is the parent's red-spotted bill, while the tapping towards the ground makes the red spot visible to the chick, demonstrating a distinctive movement.<ref>{{Cite journal|last1=Tinbergen|first1=N.|last2=Perdeck|first2=A. C.|date=1951-01-01|title=On the Stimulus Situation Releasing the Begging Response in the Newly Hatched Herring Gull Chick (Larus Argentatus Argentatus Pont.)|url=https://brill.com/view/journals/beh/3/1/article-p1_1.xml|journal=Behaviour|language=en|volume=3|issue=1|pages=1–39|doi=10.1163/156853951X00197|issn=0005-7959|url-access=subscription}}</ref> [[Frans de Waal]] studied [[bonobo]]s and [[Chimpanzee|chimps]] to understand if language was somehow evolved by gestures. He found that both apes and humans only use intentional gestures to communicate.<ref>{{Cite journal|last1=Pollick|first1=Amy S.|last2=Waal|first2=Frans B. M. de|date=2007-05-08|title=Ape gestures and language evolution|journal=Proceedings of the National Academy of Sciences|language=en|volume=104|issue=19|pages=8184–8189|doi=10.1073/pnas.0702624104|issn=0027-8424|pmid=17470779|pmc=1876592|bibcode=2007PNAS..104.8184P|doi-access=free}}</ref>
;[[Facial expression]]: Another important signal of [[Emotion in animals|emotion]] in animal communication are facial gestures. Blue and Yellow Macaws were studied to understand how they reacted to interactions with a familiar animal caretaker. Studies show that Blue and Yellow Macaws demonstrated a significant amount of blushing frequently during mutual interactions with a caretaker.<ref>{{cite journal |last1=Bertin |first1=Aline |last2=Beraud |first2=Arielle |last3=Lansade |first3=Léa |last4=Blache |first4=Marie-Claire |last5=Diot |first5=Amandine |last6=Mulot |first6=Baptiste |last7=Arnould |first7=Cécile |display-authors=3|title=Facial display and blushing: Means of visual communication in blue-and-yellow macaws (Ara Ararauna)? |journal=PLOS ONE |date=22 August 2018 |volume=13 |issue=8 |pages=e0201762 |doi=10.1371/journal.pone.0201762|pmid=30133471 |id={{ProQuest|2091762411}} |doi-access=free |pmc=6104955 |bibcode=2018PLoSO..1301762B }}</ref>  In another experiment, [[Jeffrey Mogil]] studied facial expression in mice in response to increments of increasing pain. He found that mice exhibited five recognizable facial expressions: orbital tightening, nose and cheek bulge, and changes in ear and whisker carriage.<ref>{{Cite journal|last=Mogil|first=Jeffrey S.|date=April 2009|title=Animal models of pain: progress and challenges|url=http://www.nature.com/articles/nrn2606|journal=Nature Reviews Neuroscience|language=en|volume=10|issue=4|pages=283–294|doi=10.1038/nrn2606|pmid=19259101|s2cid=205504814|issn=1471-003X|url-access=subscription}}</ref>
;[[Gaze]]-following: Social animals use gaze-following as a form of communication through monitoring head and eye orientation in other mammals.<ref name=":02">{{Cite journal|last=Shepherd|first=Stephen V.|date=2010-03-19|title=Following Gaze: Gaze-Following Behavior as a Window into Social Cognition|journal=Frontiers in Integrative Neuroscience|volume=4|page=5|doi=10.3389/fnint.2010.00005|issn=1662-5145|pmc=2859805|pmid=20428494|doi-access=free}}</ref> Studies have been conducted on apes, monkeys, dogs, birds, wolves, and tortoises, and have focused on two different tasks: "follow[ing] another's gaze into distant space" and "follow[ing] another's gaze geometrically around a visual barrier, e.g., by repositioning themselves to follow a gaze cue when faced with a barrier blocking their view".<ref>{{Cite journal|last1=Range|first1=Friederike|last2=Virányi|first2=Zsófia|date=2011-02-23|editor-last=Wylie|editor-first=Doug|title=Development of Gaze Following Abilities in Wolves (Canis Lupus)|journal=PLOS ONE|language=en|volume=6|issue=2|pages=e16888|doi=10.1371/journal.pone.0016888|issn=1932-6203|pmc=3044139|pmid=21373192| bibcode=2011PLoSO...616888R |doi-access=free}}</ref> A broad range of animals have been proven to exhibit the latter, however, only apes, dogs, wolves, and corvids (ravens) have been able to follow another's gaze into distant space. [[Marmoset]]s and [[ibis]] were unable to demonstrate "geometric gaze following". Researchers do not yet have a clear picture of the cognitive basis of gaze following, but developmental evidence indicates that "simple" gaze following and "geometric" gaze following probably rely on different cognitive mechanisms.<ref name=":02" />
;Colour change: Colour change can be separated into changes that occur during growth and development, and those triggered by mood, social context, or abiotic factors such as temperature.  The latter are seen in many taxa.  Some [[cephalopod]]s, such as the [[octopus]] and the [[cuttlefish]], have specialized skin cells ([[chromatophores]]) that can change the apparent colour, opacity, and reflectiveness of their skin.<ref name=cephalopod1>{{cite journal | last1 = Cloney | first1 = R.A. | last2 = Florey | first2 = E. | year = 1968 | title = Ultrastructure of cephalopod chromatophore organs | journal = Z. Zellforsch. Mikrosk. Anat. | volume = 89 | issue = 2| pages = 250–280 | pmid = 5700268 | doi=10.1007/bf00347297| s2cid = 26566732 }}</ref> In addition to their use for [[camouflage]], rapid changes in skin colour are used while hunting and in courtship rituals.<ref>{{cite book |title=Cephalopod Behaviour |last=Hanlon |first=R.T.|author2=Messenger, J.B. |year=1996| publisher=[[Cambridge University Press]]|isbn=978-0-521-64583-6 |page=121|url=https://books.google.com/books?id=Nxfv6xZZ6WYC&q=cephalopod+behaviour}}</ref> Cuttlefish may display two entirely different signals simultaneously from opposite sides of their body. When a male cuttlefish courts a female in the presence of other males, he displays a male pattern facing the female and a female pattern facing away, to deceive other males.<ref>{{cite news|first=Sarah |last=Williams |year=2012 |title=Two-faced fish tricks competitors |publisher=Science Now |url=http://news.sciencemag.org/sciencenow/2012/07/two-faced-fish-tricks-competitor.html |access-date=March 16, 2013 |url-status=dead |archive-url=https://web.archive.org/web/20130308094334/http://news.sciencemag.org/sciencenow/2012/07/two-faced-fish-tricks-competitor.html |archive-date=March 8, 2013 }}</ref>  Some colour signals occur in cycles. For example, when a female olive baboon begins to ovulate, her anogenital area swells and turns a bright red/pink. This signals to males that she is ready to mate.<ref name=Motluk>{{cite journal | author = Motluk, Alison | title = Big Bottom | journal = New Scientist | volume = 19 | issue = 7|url=https://www.newscientist.com/article/dn494-big-bottom.html | year = 2001}}</ref> [[Humboldt squid]] are [[bioluminescent]] and thus capable of communicating visually in dark ocean environments.<ref>[https://www.npr.org/2020/03/23/820293424/deep-sea-squid-may-communicate-through-glowing-pigmentation-researchers-find Deep Sea Squid May Communicate Through Glowing Pigmentation, Researchers Find]</ref>
;[[Bioluminescence|Bioluminescent communication]]: Communication by the production of light occurs commonly in vertebrates and invertebrates in the oceans, particularly at depths (e.g., [[angler fish]]). Two well-known forms of land bioluminescence occur in [[Firefly|fireflies]] and [[Phengodidae|glow worms]]. Other insects, insect [[larva]]e, [[annelid]]s, [[arachnid|arachnids]], and even species of [[Fungus|fungi]] possess bioluminescent abilities. Some bioluminescent animals produce the light themselves, whereas others have a [[Symbiosis|symbiotic]] relationship with bioluminescent bacteria.<ref>{{Cite web|last=Mason|first=Julia|date=July 18, 2018|title=Glowing in the Deep|url=https://thedishonscience.stanford.edu/posts/bioluminescence/|website=The Dish on Science|access-date=October 31, 2020|archive-date=May 6, 2021|archive-url=https://web.archive.org/web/20210506013533/https://thedishonscience.stanford.edu/posts/bioluminescence/|url-status=dead}}</ref> Animals exhibit bioluminescent light to lure in prey, attract a mate, or protect themselves from potential predators.<ref>{{Cite web|title=Bioluminescence {{!}} Smithsonian Ocean|url=http://ocean.si.edu/ocean-life/fish/bioluminescence|access-date=2020-10-25|website=ocean.si.edu|date=30 April 2018 |language=en}}</ref> (See also: [[List of bioluminescent organisms]])