Editing Dolphin (section)

==Behavior==
[[File:Dolphins gesture language.jpg|thumb|A pod of [[Indo-Pacific bottlenose dolphin]]s in the [[Red Sea]]]]
===Socialization===
[[File:Dolphinsurfresize.jpg|thumb|Dolphins surfing at [[Snapper Rocks]], [[Queensland]], Australia]]
Dolphins are highly social animals, often living in pods of up to a dozen individuals, though pod sizes and structures vary greatly between species and locations. In places with a high abundance of food, pods can merge temporarily, forming a ''superpod''; such groupings may exceed 1,000 dolphins. Membership in pods is not rigid; interchange is common. They establish strong social bonds, and will stay with injured or ill members, helping them to breathe by bringing them to the surface if needed.<ref>{{cite web
|title= Bottlenose Dolphins – Altruism
|author=Davidson College, biology department
|year=2001
|url=http://www.bio.davidson.edu/people/vecase/behavior/Spring2001/Ewart/Altruism.html
|access-date= March 12, 2008
|archive-url = https://web.archive.org/web/20100106122007/http://www.bio.davidson.edu/people/vecase/behavior/Spring2001/Ewart/Altruism.html
|archive-date = January 6, 2010
|url-status = dead
}}</ref> This [[altruism]] does not appear to be limited to their own species. The dolphin ''[[Moko (dolphin)|Moko]]'' in [[New Zealand]] has been observed guiding a female [[pygmy sperm whale]] together with her calf out of shallow water where they had stranded several times.<ref>{{cite news
|title= Dolphin Saves Stuck Whales, Guides Them Back to Sea
|first=Ray | last = Lilley | agency = Associated Press | work = National Geographic | date = March 12, 2008|url=http://news.nationalgeographic.com/news/2008/03/080312-AP-dolph-whal.html
|archive-url=https://web.archive.org/web/20080313141839/http://news.nationalgeographic.com/news/2008/03/080312-AP-dolph-whal.html
|url-status=dead
|archive-date=March 13, 2008
|access-date= July 8, 2012 }}</ref> They have also been seen protecting swimmers from sharks by swimming circles around the swimmers<ref>{{cite news
|title= Dolphins save swimmers from shark
|publisher=CBC News
|url=https://www.cbc.ca/news/world/dolphins-save-swimmers-from-shark-1.513716
|access-date= March 11, 2007
| date=November 24, 2004}}</ref><ref>{{cite web
| last =Celizic
| first =Mike
| title =Dolphins save surfer from becoming shark's bait
| publisher =Today
| date =November 8, 2007
| url = https://www.today.com/news/dolphins-save-surfer-becoming-sharks-bait-2d80555123
| archive-url =https://web.archive.org/web/20071110040906/http://today.msnbc.msn.com/id/21689083/?GT1=10547
| archive-date =November 10, 2007
| access-date = March 2, 2022 }}</ref> or charging the sharks to make them go away.

Dolphins communicate using a variety of clicks, whistle-like sounds and other vocalizations. Dolphins also use [[nonverbal communication]] by means of touch and [[Posture (psychology)|posturing]].<ref>{{cite book|title=Dolphin Mysteries: Unlocking the Secrets of Communication|url={{google books |plainurl=y |id=3gXV0lUeOV4C|page=83}}|access-date=March 16, 2014|date=2008|publisher=Yale University Press|isbn=978-0-300-12112-4|page=83}}</ref>

Dolphins also display culture, something long believed to be unique to humans (and possibly other [[primate]] species). In May 2005, a discovery in Australia found [[Indo-Pacific bottlenose dolphin]]s (''Tursiops aduncus'') teaching their young to use tools. They cover their [[snout]]s with [[sea sponge|sponges]] to protect them while foraging. This knowledge is mostly transferred by mothers to daughters, unlike [[simian]] primates, where knowledge is generally passed on to both sexes. Using sponges as mouth protection is a learned behavior.<ref>{{cite web
|title= Dolphins teach their children to use sponges
|author=Rowan Hooper
|year=2005
|url=https://www.newscientist.com/article/dn7475-dolphins-teach-their-children-to-use-sponges/
|access-date= June 28, 2021}}</ref> Another learned behavior was discovered among river dolphins in Brazil, where some male dolphins use weeds and sticks as part of a sexual display.<ref>{{Cite news
|title= Dolphins woo females with bunches of weeds
|author=Nic Fleming
|url= https://www.telegraph.co.uk/news/earth/earthnews/3317206/Dolphins-woo-females-with-bunches-of-weeds.html
|archive-url=https://web.archive.org/web/20071208002950/http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2007/12/05/eadolphin105.xml
|archive-date=December 8, 2007
|access-date= March 2, 2022
| work=The Daily Telegraph
| location=London| date=December 5, 2007}}</ref>

Forms of care-giving between fellows and even for members of different species<ref>{{cite web |last1=Bathgate |first1=Adrian |title=Dolphin saves 2 whales stuck on New Zealand beach |url=https://www.reuters.com/article/us-newzealand-dolphin-idUSWEL1524120080313 |website=Reuters |access-date=March 2, 2022 |date=March 13, 2008}}</ref> (see [[Moko (dolphin)]]) are recorded in various species –  such as trying to save weakened fellows<ref>{{cite web|url=https://www.bbc.co.uk/nature/21146455|title=Dolphins try to save dying companion|date=January 28, 2013|access-date=December 30, 2016|publisher=BBC}}</ref> or female [[pilot whale]]s holding up dead calves for long periods.

Dolphins engage in acts of aggression towards each other. The older a male dolphin is, the more likely his body is to be covered with bite scars. Male dolphins can get into disputes over companions and females. Acts of aggression can become so intense that targeted dolphins sometimes go into exile after losing a fight.

Male bottlenose dolphins have been known to engage in [[infanticide (zoology)|infanticide]]. Dolphins have also been known to kill [[porpoises]] (porpicide) for reasons which are not fully understood, as porpoises generally do not share the same diet as dolphins and are therefore not competitors for food supplies.<ref>{{Cite news |date=2023-08-24 |title=Dolphin spotters shaken by Ceredigion porpoise killing |language=en-GB |work=BBC News |url=https://www.bbc.com/news/uk-wales-66589355 |access-date=2023-08-24}}</ref><ref>{{cite web
|title= Is Flipper A Senseless Killer?
|author= George Johnson
|url= http://www.txtwriter.com/Onscience/Articles/Flipper.html
|access-date= December 17, 2006
|url-status= dead
|archive-url= https://web.archive.org/web/20061111055736/http://www.txtwriter.com/Onscience/Articles/Flipper.html
|archive-date= November 11, 2006
}}</ref> The [[Cornwall Wildlife Trust]] records about one such death a year. Possible explanations include misdirected infanticide, misdirected sexual aggression or [[play behaviour]].<ref>[https://www.bbc.com/news/uk-england-devon-37616961 Dolphin pictured killing porpoise by flipping it into air], BBC</ref>

===Reproduction and sexuality{{anchor|Reproductive_system}}===
{{See also|Bottlenose dolphin#Reproduction|Dusky dolphin#Social behavior and reproduction|Short-beaked common dolphin#Reproduction}}
[[File:cmglee Horniman dolphin skin skeleton.jpg|thumb|A skin-skeletal preparation<!-- of what?! -->.]]

Dolphin [[copulation (zoology)|copulation]] happens belly to belly; though many species engage in lengthy [[foreplay]], the actual act is usually brief, but may be repeated several times within a short timespan.<ref name=Silva>{{cite web|first1=J. Jr. |last1=Silva |first2=F. |last2=Silva |first3=I. |last3=Sazima |year=2005 |url=http://mardecetaceos.net/media_files/download/04spinner-dolphin.pdf |title=Rest, nurture, sex, release, and play: diurnal underwater behaviour of the spinner dolphin at Fernando de Noronha Archipelago, SW Atlantic – Mating behaviour |access-date=March 16, 2014 |url-status=dead |archive-url=https://web.archive.org/web/20140316211613/http://mardecetaceos.net/media_files/download/04spinner-dolphin.pdf |archive-date=March 16, 2014 }}</ref> The [[gestation period]] varies with species; for the small [[tucuxi dolphin]], this period is around 11 to 12 months,<ref>CMS [http://www.cms.int/reports/small_cetaceans/data/S_fluviatilis/s_fluviatilis.htm Sotalia fluviatilis – Reproduction] {{Webarchive|url=https://web.archive.org/web/20130520100257/http://www.cms.int/reports/small_cetaceans/data/S_fluviatilis/s_fluviatilis.htm |date=May 20, 2013 }}, article. Retrieved March 16, 2013.</ref> while for the orca, the gestation period is around 17 months.<ref>[http://marinebio.org/species.asp?id=84 Orcas (Killer Whales), Orcinus orca – Life History], Marinebio.org. Retrieved March 16, 2014.</ref> Typically dolphins give birth to a single calf, which is, unlike most other mammals, born tail first in most cases.<ref name="Simmonds2007">{{cite book|last=Simmonds|first=Mark|title=Whales and Dolphins of the World|url={{google books |plainurl=y |id=TQxyo8O5KD8C|page=32}}|year=2007|publisher=New Holland Publishers|isbn=978-1-84537-820-2|page=32}}{{Dead link|date=March 2024 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> They usually become sexually active at a young age, even before reaching [[sexual maturity]].<ref name=Silva/> The age of sexual maturity varies by species and sex.<ref>{{Cite book
|title=Reproductive Parameters of Dolphins
|author1=W. Perrin |author2=S. Reilly |year=1984|url=http://swfsc.noaa.gov/publications/CR/1984/8470.PDF}}</ref>

Dolphins are known to display [[Animal co-opted sexual behavior|non-reproductive sexual behavior]], engaging in [[Animal sexual behavior#Autoeroticism or masturbation|masturbation]],<ref>{{Cite book |last1=Würsig |first1=Bernd |url=https://books.google.com/books?id=mfjYEAAAQBAJ&pg=PA164 |title=Sex in Cetaceans: Morphology, Behavior, and the Evolution of Sexual Strategies |last2=Orbach |first2=Dara N. |date=2023-09-25 |publisher=Springer Nature |isbn=978-3-031-35651-3 |language=en}}</ref> stimulation of the genital area of other individuals using the [[rostrum (anatomy)|rostrum]] or flippers, and [[Homosexual behavior in animals|homosexual contact]].<ref name=Silva/><ref>{{Cite book
|title=Homosexual Behaviour in Animals – an Evolutionary perspective.
|author1=Volker Sommer |author2=Paul L. Vasey |year=2006
|chapter=Chapter 4
|chapter-url={{google books |plainurl=y |id=KXM3F59y1jkC}}}}</ref><ref>{{Cite book
|title=Biological Exuberance – Animal Homosexuality and Natural Diversity
|author=Bruce Bagemihl
|url={{google books |plainurl=y |id=0xpi2NI-Dz4C}}
|year=1999}}</ref>

Various species of dolphin have been known to engage in sexual behavior including copulation with dolphins of other species, and occasionally exhibit [[Cross-species sex|sexual behavior towards other animals]], including humans.<ref>{{Cite news|url=http://www.huffingtonpost.com/2012/09/06/frisky-dolphin-tries-to-get-busy-divers_n_1862148.html|title=SCARY VIDEO: Dolphin Gets Too Frisky With Scuba Divers|first1=David|last1=Moye|date=September 7, 2012|newspaper=HuffPost|access-date=December 30, 2016}}</ref><ref>{{Cite book |author1=Amy Samuels |title=Cetaceans that are typically lonely and seek human company |author2=Lars Bejder |author3=Rochelle Constantine |author4=Sonja Heinrich |year=2003 |pages=266–268 |chapter=chapter 15 Marine Mammals: Fisheries, Tourism and Management Issues |author-link3=Rochelle Constantine |access-date=December 17, 2006 |chapter-url=http://whitelab.biology.dal.ca/lb/Samuels%20Bejder%20et%20al%202003.pdf}}</ref> Sexual encounters may be violent, with male bottlenose dolphins sometimes showing aggressive behavior towards both females and other males.<ref>{{cite journal|last=Scott|first=Erin|author2=Mann, Janet |author3=Watson-Capps, Jana |author4=Sargeant, Brooke |author5= Connor, Richard |s2cid=4502911|title=Aggression in bottlenose dolphins: Evidence for sexual coercion, male-male competition, and female tolerance through analysis of tooth-rake marks and behaviour|journal=Behaviour|year=2005|volume=142|issue=1|pages=21–44|doi=10.1163/1568539053627712}}</ref> Male dolphins may also work together and attempt to herd females in [[Estrus#Estrus|estrus]], keeping the females by their side by means of both physical aggression and intimidation, to increase their chances of reproductive success.<ref>{{Cite book
|title=Two levels of alliance formation among male bottlenose dolphins
|author1=R. Connor |author2=R. Smolker |author3=A. Richards |year=1992|url=http://www.pnas.org/content/89/3/987.full.pdf}}</ref>

===Sleeping===
[[File:דולפין ישן.svg|thumb|Sleeping dolphin in captivity: a tail kick reflex keeps the dolphin's blowhole above the water.]]
{{further|Sleep in animals}}

Generally, dolphins sleep with only one brain [[Cerebral hemisphere|hemisphere]] in [[slow-wave sleep]] at a time, thus maintaining enough consciousness to breathe and to watch for possible predators and other threats. Sleep stages earlier in sleep can occur simultaneously in both hemispheres.<ref>
{{cite conference
| last = Mukhametov | first = L. M.
|author2=Supin, A. Ya.
| title = Sleep and vigil in dolphins
| book-title = Marine mammals
| location= Moscow
| publisher=[[Nauka (publisher)|Nauka]]
|year=1978}}</ref><ref name="Mukhametov, 1984">{{Cite book
| last=Mukhametov| first=Lev
| chapter=Sleep in Marine Mammals
| title=Sleep Mechanisms
| year=1984
| volume=8
| pages=227–238
| doi=10.1007/978-3-642-69554-4_17
| series=Experimental Brain Research Supplementum
| doi-broken-date=November 1, 2024
| isbn=978-3-642-69556-8}}</ref><ref>{{Cite journal
|title= Excerpts from 'Sleep in marine mammals', L.M. Mukhametov
|author=Dallas Grasby
|year=1994
|url=http://www.bio.net/bionet/mm/neur-sci/1994-August/003910.html
|journal=Experimental Brain Research
|volume= 8 (suppl.)
|access-date= February 11, 2008}}</ref>
In captivity, dolphins seemingly enter a fully asleep state where both eyes are closed and there is no response to mild external stimuli. In this case, respiration is automatic; a tail kick [[reflex]] keeps the blowhole above the water if necessary. [[anesthesia|Anesthetized]] dolphins initially show a tail kick reflex.<ref>{{cite journal|last=McCormick|first=James G.|title=Behavioral Observations of Sleep and Anesthesia in the Dolphin: Implications for Bispectral Index Monitoring of Unihemispheric Effects in Dolphins|journal=Anesthesia & Analgesia|year=2007|volume=104|issue=1|pages=239–241|doi=10.1213/01.ane.0000250369.33700.eb|pmid=17179314|s2cid=40939919 |doi-access=free}}</ref>  Though a similar state has been observed with wild [[sperm whale]]s, it is not known if dolphins in the wild reach this state.<ref>{{cite news
|title= Sperm whales caught 'cat napping'
|work=BBC News|url=http://news.bbc.co.uk/1/hi/scotland/edinburgh_and_east/7254522.stm
|access-date= April 9, 2008 | date=February 20, 2008
}}</ref> The [[Indus river dolphin]] has a sleep method that is different from that of other dolphin species. Living in water with strong currents and potentially dangerous floating debris, it must swim continuously to avoid injury. As a result, this species sleeps in very short bursts which last between 4 and 60&nbsp;seconds.<ref>{{cite book |first1=G. Neil |last1=Martin |first2= Neil R. |last2=Carlson |first3=William |last3=Buskist |year=1997|url={{google books|plainurl=y|id=j4XE89_3vj8C}} |title=Psychology, third edition |publisher=Pearson Allyn & Bacon |page=383 |isbn=978-0-273-71086-8}}</ref>

===Feeding===
There are various feeding methods among and within species, some apparently exclusive to a single population. Fish and squid are the main food, but the false killer whale and the orca also feed on other marine mammals. Orcas on occasion also hunt whale species larger than themselves.<ref name="FactsDiet">{{Cite web|url=http://www.whalefacts.org/dolphins-diet/|archive-url=https://web.archive.org/web/20130927175656/http://www.whalefacts.org/dolphins-diet/|url-status= dead|title=Dolphin's diet|archive-date=September 27, 2013}}</ref> Different breeds of dolphins vary widely in the number of teeth they possess. The orca usually carries 40–56 teeth while the popular bottlenose dolphin has anywhere from 72 to 116 conical teeth and its smaller cousin the common dolphin has 188–268 teeth: the number of teeth that an individual carries varies widely between within a single species. Hybrids between common and bottlenose bred in captivity had a number of teeth intermediate between that of their parents.

One common feeding method is herding, where a pod squeezes a school of fish into a small volume, known as a [[bait ball]]. Individual members then take turns plowing through the ball, feeding on the stunned fish.<ref name=FactsDiet /> Corralling is a method where dolphins chase fish into shallow water to catch them more easily.<ref name=FactsDiet /> Orcas and bottlenose dolphins have also been known to drive their prey onto a beach to feed on it, a behaviour known as beach or strand feeding.<ref>{{cite web
|title=Coastal Stock(s) of Atlantic Bottlenose Dolphin: Status Review and Management Proceedings and Recommendations from a Workshop held in Beaufort, North Carolina, 13 September 1993&nbsp;– 14 September 1993
|url=http://www.nmfs.noaa.gov/pr/pdfs/species/coastalbottlenosestock.pdf
|author=U.S. Department of Commerce National Oceanic and Atmospheric Administration National Marine Fisheries Service
|pages=56–57}}</ref><ref>Gregory K. Silber, Dagmar Fertl (1995) – ''Intentional beaching by bottlenose dolphins (Tursiops truncatus) in the Colorado River Delta, Mexico.''</ref> Some species also whack fish with their flukes, stunning them and sometimes knocking them out of the water.<ref name=FactsDiet />

Reports of cooperative human-dolphin fishing date back to the [[ancient Rome|ancient Roman]] author and [[natural philosophy|natural philosopher]] [[Pliny the Elder]].<ref>{{cite journal
|title= Variability in the diet of bottlenose dolphin, ''Tursiops truncatus'', in Galician waters, north-western Spain, 1990–2005
|author1=M.B. Santos |author2=R. Fernández |author3=A. López |author4=J.A. Martínez |author5=G.J. Pierce |s2cid=85767272 |year=2007
|doi=10.1017/S0025315407055233
|journal= Journal of the Marine Biological Association of the UK
|volume= 87
|issue=1 |page= 231|bibcode=2007JMBUK..87..231S }}</ref> A modern human-dolphin partnership currently operates in [[Laguna, Santa Catarina|Laguna]], Santa Catarina, Brazil. Here, dolphins drive fish towards fishermen waiting along the shore and signal the men to cast their nets. The dolphins' reward is the fish that escape the nets.<ref>{{Cite news
|title= Brazil's sexiest secret
|url=https://www.telegraph.co.uk/travel/southamerica/brazil/734722/Brazil%27s-sexiest-secret.html
|archive-url=https://web.archive.org/web/20080313043242/http://www.telegraph.co.uk/travel/southamerica/brazil/734722/Brazil%27s-sexiest-secret.html
|archive-date=March 13, 2008
|access-date= March 11, 2007
| work=The Daily Telegraph
| location=London
|url-status= dead
| date=March 8, 2006}}</ref><ref>{{cite web
|title= Bottlenose Dolphins in Laguna Requesting a Throw Net Supporting material for Dr. Nissani's presentation at the 2007 International Ethological Conference
|author= Moti Nissani
|website= [[YouTube]]
|year=2007
|url=https://www.youtube.com/watch?v=ECk0yMifmzw
| archive-url=https://ghostarchive.org/varchive/youtube/20211211/ECk0yMifmzw| archive-date=2021-12-11 | url-status=live|access-date=February 13, 2008}}{{cbignore}}</ref>

In [[Shark Bay]], Australia, dolphins catch fish by trapping them in huge [[conch|conch shell]]s.<ref>{{cite web|last=Hunt|first=Katie|title=Dolphins are learning smart fish-catching trick from peers, not mothers|url=https://www.cnn.com/2020/06/25/world/dolphins-tools-shell-learning-scn/index.html|date=June 25, 2020|access-date=June 25, 2020|work=CNN}}</ref> In "shelling", a dolphin brings the shell to the surface and shakes it, so that fish sheltering within fall into the dolphin's mouth. From 2007 to 2018, in 5,278 encounters with dolphins, researchers observed 19 dolphins shelling 42 times. The behavior spreads mainly within generations, rather than being passed from mother to offspring.

===Vocalization===
[[File:Dolphin1.jpg|thumb|upright=1.35|[[Spectrogram]] of dolphin vocalizations. Whistles, whines, and clicks are visible as upside down V's, horizontal striations, and vertical lines, respectively.]]

Dolphins are capable of making a broad range of sounds using nasal airsacs located just below the blowhole. Roughly three categories of sounds can be identified: [[frequency modulated]] whistles, burst-pulsed sounds, and clicks. Dolphins communicate with whistle-like sounds produced by vibrating connective tissue, similar to the way human vocal cords function,<ref>{{cite web |last = Viegas |first = Jennifer |title = Dolphins Talk Like Humans |work = Discovery News |year = 2011 |url = http://news.discovery.com/animals/dolphin-talk-communication-humans-110906.html |access-date = September 19, 2011 |archive-date = September 24, 2011 |archive-url = https://web.archive.org/web/20110924060555/http://news.discovery.com/animals/dolphin-talk-communication-humans-110906.html |url-status = dead }}</ref> and through burst-pulsed sounds, though the nature and extent of that ability is not known. The clicks are directional and are for echolocation, often occurring in a short series called a click train. The click rate increases when approaching an object of interest. Dolphin echolocation clicks are amongst the [[Whale sound|loudest sounds made by marine animals]].<ref name="Au2012">{{cite book|last=Au|first=Whitlow W.L.|title=The Sonar of Dolphins|url={{google books |plainurl=y |id=NEXTBwAAQBAJ}}|date=December 6, 2012|publisher=Springer Science & Business Media|isbn=978-1-4612-4356-4}}</ref>

Bottlenose dolphins have been found to have signature whistles, a whistle that is unique to a specific individual. These whistles are used in order for dolphins to communicate with one another by identifying an individual. It can be seen as the dolphin equivalent of a name for humans.<ref>{{cite news |url=https://www.bbc.co.uk/news/science-environment-23410137 |title=Dolphins 'call each other by name' |date=July 22, 2013 |work=BBC News}}</ref> These signature whistles are developed during a dolphin's first year; it continues to maintain the same sound throughout its lifetime.<ref>{{cite journal|last=Janik|first=Vincent|author2=Laela Sayigh|title=Communication in bottlenose dolphins: 50 years of signature whistle research|journal=Journal of Comparative Physiology|date=May 7, 2013|volume=199|issue=6|pages=479–489|doi=10.1007/s00359-013-0817-7|pmid=23649908|s2cid=15378374}}<!--|access-date=January 30, 2014--></ref> In order to obtain each individual whistle sound, dolphins undergo vocal production learning. This consists of an experience with other dolphins that modifies the signal structure of an existing whistle sound. An auditory experience influences the whistle development of each dolphin. Dolphins are able to communicate to one another by addressing another dolphin through mimicking their whistle. The signature whistle of a male bottlenose dolphin tends to be similar to that of his mother, while the signature whistle of a female bottlenose dolphin tends to be more distinguishing.<ref>{{cite web |url=http://www.whoi.edu/science/B/people/kamaral/marinemammalacoustics.html |title=Marine Mammal vocalizations: language or behavior? |date=August 24, 2013}}</ref> Bottlenose dolphins have a strong memory when it comes to these signature whistles, as they are able to relate to a signature whistle of an individual they have not encountered for over twenty years.<ref>{{cite web |url=http://news.uchicago.edu/article/2013/08/06/dolphins-keep-lifelong-social-memories-longest-non-human-species |title=Dolphins keep lifelong social memories, longest in a non-human species |date=August 24, 2013}}</ref> Research done on signature whistle usage by other dolphin species is relatively limited. The research on other species done so far has yielded varied outcomes and inconclusive results.<ref>Emily T. Griffiths (2009). "[http://www.seawatchfoundation.org.uk/wp-content/uploads/2012/08/Griffiths2009_SBCDwhistle-repertoire.pdf Whistle repertoire analysis of the short beaked Common Dolphin, ''Delphinus delphis'', from the Celtic Deep and the Eastern Tropical Pacific Ocean]", Master's Thesis, School of Ocean Sciences
Bangor University</ref><ref>Melba C. Caldwell et al. – ''Statistical Evidence for Signature Whistles in the Spotted Dolphin, ''Stenella plagiodon''.''</ref><ref>Melba C. Caldwell et al. – ''Statistical Evidence for Signature Whistles in the Pacific Whitesided Dolphin, ''Lagenorhynchus obliquidens''.''</ref><ref>Rüdiger Riesch et al. – ''Stability and group specificity of stereotyped whistles in resident killer whales, Orcinus orca, off British Columbia.''</ref>

Because dolphins are generally associated in groups, communication is necessary. Signal masking is when other similar sounds (conspecific sounds) interfere with the original acoustic sound.<ref>{{cite journal|last=Quick|first=Nicola|author2=Vincent Janik|title=Whistle Rates of Wild Bottlenose Dolphins (''Tursiops truncatus''): Influences of Group Size and Behavior|journal=Journal of Comparative Psychology|year=2008|volume=122|issue=3|pages=305–311|doi=10.1037/0735-7036.122.3.305|pmid=18729659}}<!--|access-date=January 27, 2014--></ref> In larger groups, individual whistle sounds are less prominent. Dolphins tend to travel in pods, upon which there are groups of dolphins that range from a few to many. Although they are traveling in these pods, the dolphins do not necessarily swim right next to each other. Rather, they swim within the same general vicinity. In order to prevent losing one of their pod members, there are higher whistle rates. Because their group members were spread out, this was done in order to continue traveling together.

===Jumping and playing===
[[File:PacificWhiteSidedDolphine.jpg|thumb|Pacific white-sided dolphins porpoising.]]
Dolphins frequently leap above the water surface, this being done for various reasons. When travelling, jumping can save the dolphin energy as there is less friction while in the air.<ref name=Weihs>{{cite journal|last=Weihs|first=D.|title=Dynamics of Dolphin Porpoising Revisited|journal=Integrative and Comparative Biology |year=2002| volume=42| issue=5| pages=1071–1078| doi=10.1093/icb/42.5.1071| pmid=21680390|doi-access=free}}</ref> This type of travel is known as porpoising.<ref name=Weihs /> Other reasons include orientation, social displays, fighting, [[non-verbal communication]], entertainment and attempting to dislodge [[parasite]]s.<ref>David Lusseau (2006), ''Why do dolphins jump? Interpreting the behavioural repertoire of bottlenose dolphins (Tursiops sp.) in Doubtful Sound, New Zealand''</ref><ref>Corey Binns – LiveScience (2006), [http://www.livescience.com/678-dolphins-spin.html How Dolphins Spin, and Why], article. Retrieved September 8, 2013.</ref>

Dolphins show various types of playful behavior, often including objects, self-made [[bubble ring]]s, other dolphins or other animals.<ref name="Walker2007">{{Cite book|last=Walker|first=Sally M. |title=Dolphins|url={{google books|plainurl=y|id=5Buh9FtAG8AC|page=6}}|date=November 2007|publisher=Lerner Publications|isbn=978-0-8225-6767-7|pages=6, 30}}</ref><ref name=dolphinplay>Robin D. Paulos (2010), ''Play in Wild and Captive Cetaceans''</ref><ref>{{cite journal |journal=Journal of Comparative Psychology |year=2000 |pages=98–106 |volume=l14 |issue=1 |doi=10.1037/0735-7036.114.1.98 |pmid=10739315 |title=Bubble Ring Play of Bottlenose Dolphins (''Tursiops truncatus''): Implications for Cognition |author1=Brenda McCowan |author2=Lori Marino |author3=Erik Vance |author4=Leah Walke |author5=Diana Reiss |url=http://faculty.vetmed.ucdavis.edu/faculty/bjmccowan/Pubs/McCowanetal.JCP.2000.pdf |access-date=August 2, 2010 |archive-url=https://web.archive.org/web/20100610140808/http://faculty.vetmed.ucdavis.edu/faculty/bjmccowan/Pubs/McCowanetal.JCP.2000.pdf |archive-date=June 10, 2010 |url-status=dead |df=mdy-all }}</ref> When playing with objects or small animals, common behavior includes carrying the object or animal along using various parts of the body, passing it along to other members of the group or taking it from another member, or throwing it out of the water.<ref name=dolphinplay /> Dolphins have also been observed harassing animals in other ways, for example by dragging birds underwater without showing any intent to eat them.<ref name=dolphinplay /> Playful behaviour that involves another animal species with active participation of the other animal has also been observed. Playful dolphin interactions with humans are the most obvious examples, followed by those with [[humpback whale]]s and [[dog]]s.<ref>Mark H. Deakos et al. (2010), ''Two Unusual Interactions Between a Bottlenose Dolphin (''Tursiops truncatus'') and a Humpback Whale (''Megaptera novaeangliae'') in Hawaiian Waters.''</ref><ref>Cathy Hayes for Irish Central (2011), [http://www.irishcentral.com/news/Amazing-footage-of-a-dog-playing-with-a-dolphin-off-the-coast-of-Ireland--VIDEO-127888298.html Amazing footage of a dog playing with a dolphin off the coast of Ireland], article. Retrieved September 8, 2013.</ref>

Juvenile dolphins off the coast of Western Australia have been observed chasing, capturing, and chewing on [[blowfish]].<ref>{{cite news|last1=Staff writers|title='Puff, puff, pass': How WA's dolphins are using blowfish to get high|url=http://www.watoday.com.au/wa-news/puff-puff-pass-how-was-dolphins-using-blowfish-to-get-high-20170208-gu86nv.html|access-date=June 9, 2017|work=WAToday|issue=February 8, 2017|date=February 8, 2017}}</ref> While some reports state that the dolphins are becoming intoxicated on the [[tetrodotoxin]] in the fishes' skin,<ref>{{cite magazine|url=https://www.vice.com/en/article/apparently-dolphins-in-australia-like-to-get-stoned-by-chewing-on-toxic-blowfish-vgtrn/|title=Apparently Dolphins in Australia Like to Get Stoned by Chewing on Toxic Blowfish|magazine=Vice|first=Brian|last=Moylan|date=February 10, 2017|access-date=April 6, 2017}}</ref> other reports have characterized this behavior as the normal curiosity and exploration of their environment in which dolphins engage.<ref>{{cite web|last1=Wilcox|first1=Christie|title=Do Stoned Dolphins Give 'Puff Puff Pass' A Whole New Meaning?|url=http://blogs.discovermagazine.com/science-sushi/2013/12/30/stoned-dolphins-give-puff-puff-pass-whole-new-meaning/|website=Science Sushi|publisher=Discover|access-date=June 9, 2017|date=December 30, 2013|archive-date=November 14, 2019|archive-url=https://web.archive.org/web/20191114073142/http://blogs.discovermagazine.com/science-sushi/2013/12/30/stoned-dolphins-give-puff-puff-pass-whole-new-meaning/|url-status=dead}}</ref>

===Tail-walking===
Although this behaviour is highly unusual in wild dolphins, several [[Indo-Pacific bottlenose dolphin]]s (''Tursiops aduncus'') of the [[Port River]], north of [[Adelaide]], [[South Australia]], have been seen to have exhibit "tail-walking".<ref name=dd2018/><ref name=study2018>{{cite journal|vauthors=Bossley M, Steiner A, Brakes P, Shrimpton J, Foster C, Rendell L |title=Tail walking in a bottlenose dolphin community: the rise and fall of an arbitrary cultural 'fad'. |journal= [[Biol. Lett.]] |date= September 2018 |volume= 14| issue=9| doi= 10.1098/rsbl.2018.0314| pmid= 30185606| pmc= 6170752}}</ref> This activity mimicks a standing posture, using the tail to run backwards along the water.<ref name=mess2018>{{cite web| url=https://www.adelaidenow.com.au/messenger/west-beaches/the-incredible-tale-of-billie-the-port-river-dolphin-the-worlds-first-wild-tailwalker/news-story/8cae9ccf3771a93e149cbd2e62fb1b27| website= [[Adelaide Now]]| title=The incredible tale of Billie the Port River dolphin — the world's first wild tailwalker| series= Portside Messenger | date=9 May 2018| first=Ashleigh |last=Pisani}}</ref> To perform this movement, the dolphin "forces the majority of its body vertically out of the water and maintains the position by vigorously pumping its tail".<ref name=study2018/>

This started in 1988 when a female named Billie was rescued after becoming trapped in a polluted [[marina]],<ref name="Sutton 2022">{{cite web | last=Sutton | first=Malcolm | title=Why are the dolphins dying? | website=ABC News| publisher= Australian Broadcasting Corporation | date=4 April 2022 | url=https://www.abc.net.au/news/2022-04-04/dolphin-deaths-mystery-adelaide-dolphin-sanctuary/100795994 | access-date=4 April 2022}}</ref> and spent two weeks recuperating with captive dolphins. Billie had previously been observed swimming and frolicking with [[racehorse]]s exercising in the Port River in the 1980s. After becoming trapped in a reedy estuary further down the coast, she was rescued and placed with several captive dolphins at a marine park to recuperate. There she observed the captive dolphins performing tail-walking.<ref name=mess2018/> After being returned to the Port River, she continued to perform this trick, and another dolphin, Wave, copied her. Wave, a very active tail-walker, passed on the skill to her daughters, Ripple and Tallula.<ref name=dd2018>{{cite web | title=Billie | website=Dolphin Dock | date=15 February 2018 | url=https://www.dolphindock.com.au/meet-the-dolphins/billie/ | access-date=4 April 2022}}</ref>

After Billie's premature death, Wave started tail-walking much more frequently, and other dolphins in the group were observed also performing the behaviour.<ref name=study2018/> In 2011, up to 12 dolphins were observed tail-walking, but only females appeared to learn the skill.<ref name=gentside>{{cite web | title=The amazing story of Billie, the dolphin who taught her peers how to moonwalk | website=Gentside UK | date=15 October 2018 | url=https://www.gentside.co.uk/animal/the-amazing-story-of-billie-the-dolphin-who-taught-her-peers-how-to-moonwalk_art1800.html | access-date=4 April 2022}}</ref> In October 2021, a dolphin was observed tail-walking over a number of hours.<ref name="Sutton 2022"/>

Scientists have found the spread of this behaviour, through up to two generations, surprising, as it brings no apparent advantage, and is very energy-consuming.<ref name=gentside/> A 2018 study by Mike Rossley et al. suggested:<ref name=dd2018/>{{blockquote|Social learning is the most likely mechanism for the introduction and spread of this unusual behaviour, which has no known adaptive function. These observations demonstrate the potential strength of the capacity for spontaneous imitation in bottlenose dolphins, and help explain the origin and spread of foraging specializations observed in multiple populations of this genus.}}