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{{Short description|Species of mammal}}
{{Use dmy dates|date=May 2020}}
{{Speciesbox
| name = Spinner dolphin<ref name=MSW3>{{MSW3 Cetacea|id=14300091}}</ref>
| image = A_spinner_dolphin_in_the_Red_Sea.jpg
| image_caption = A spinner dolphin in the Red Sea
| image2 = Spinner dolphin size.svg
| image2_caption = Size compared to an average human
| status = LC
| status_system = IUCN3.1
| status_ref = <ref name="iucn">{{cite iucn |last1=Braulik |first1=G. |last2=Reeves |first2=R. |year=2018 |title=''Stenella longirostris'' |volume=2018 |page=e.T20733A50375784 |doi=10.2305/IUCN.UK.2018-2.RLTS.T20733A50375784.en |access-date=31 December 2021 }}</ref>
| status2 = CITES_A2
| status2_system = CITES
| status2_ref = <ref>{{Cite web|title=Appendices {{!}} CITES|url=https://cites.org/eng/app/appendices.php|access-date=2022-01-14|website=cites.org}}</ref>
| genus = Stenella
| species = longirostris
| authority = ([[John Edward Gray|Gray]], 1828)
| range_map = cetacea_range_map_Spinner_Dolphin.PNG
| range_map_caption = Spinner Dolphin range
| subdivision_ranks = Subspecies
| subdivision =
*''S. l. orientalis''
*''S. l. centroamericana''
*''S. l. longirostris''
*''S. l. roseiventris''
}}

The '''spinner dolphin''' ('''''Stenella longirostris''''') is a small [[dolphin]] found in off-shore tropical waters around the world. It is famous for its acrobatic displays in which it rotates around its longitudinal axis as it leaps through the air. It is a member of the [[family (biology)|family]] [[Delphinidae]] of [[toothed whale]]s.

==Taxonomy==
The spinner dolphin is sometimes referred to as the '''long-snouted dolphin''', particularly in older texts, to distinguish it from the similar [[Clymene dolphin]], which is often called the short-snouted spinner dolphin. The species was described by [[John Edward Gray|John Gray]] in 1828. The four named subspecies are:

*'''Eastern spinner dolphin''' (''S. l. orientalis''), from the tropical eastern Pacific.
*'''Central American''' or '''Costa Rican spinner dolphin''' (''S. l. centroamericana''), also found in the tropical eastern Pacific.
*'''Gray's''' or '''Hawaiian spinner dolphin''' (''S. l. longirostris''), from the central Pacific Ocean around Hawaii but represents a mixture of broadly similar subtypes found worldwide.
*'''Dwarf spinner dolphin''' (''S. l. roseiventris''), first found in the Gulf of Thailand.

The species, though, displays greater variety than these subspecies might indicate. A hybrid form characterized by its white belly inhabits the eastern Pacific. Other less distinct groupings inhabit other oceans.

The species name comes from the Latin word for "long-beaked."

==Description==
Spinner dolphins are small cetaceans with a slim build. Adults are typically 129–235 cm long and reach a body mass of 23–79 kg.<ref>{{cite journal |last1=Perrin |first1=William F. |last2=Dolar |first2=Ma. Louella L. |last3=Chan |first3=Cynthia M. |last4=Chivers |first4=Susan J. |title=Length-weight relationships in the spinner dolphin (''Stenella longirostris'') |journal=Marine Mammal Science |date=October 2005 |volume=21 |issue=4 |pages=765–778 |doi=10.1111/j.1748-7692.2005.tb01264.x }}</ref> This species has an elongated [[Rostrum (anatomy)#Vertebrates|rostrum]] and a triangular or subtriangular [[dorsal fin]].<ref name=Perrin>{{cite journal |last1=Perrin |first1=William F. |title=Stenella longirostris |journal=Mammalian Species |date=1998 |issue=599 |pages=1–7 |doi=10.2307/3504456 |jstor=3504456 |doi-access=free }}</ref> Spinner dolphins generally have tripartite color patterns. The dorsal area is dark gray, the sides light gray, and the underside pale gray or white.<ref>{{cite journal |last1=Perrin |first1=William F. |title=Color patterns of spinner porpoises (''Stenella'' cf. ''S. longirostris'') of the eastern Pacific and Hawaii, with comments on delphinid pigmentation |journal=Fishery Bulletin |volume=70 |issue=3 |date=1972 |pages=983–1003 |publisher=National Marine Fisheries Service |url=https://books.google.com/books?id=Dp_YobyydloC&pg=PA983 }}</ref> Also, a dark band runs from the eye to the flipper, bordered above by a thin, light line. However, the spinner dolphin has more geographic variation in form and coloration than other cetaceans. In the open waters of eastern Pacific, dolphins have relatively small skulls with short rostra.<ref name=Perrin/> A dwarf form of spinner dolphin occurs around southeast Asia.<ref name=Perrin1989>{{cite journal |last1=perrin |first1=William F. |last2=Miyazaki |first2=Nobuyuki |last3=Kasuya |first3=Toshio |title=A dwarf form of the spinner dolphin (''Stenella longirostris'') from Thailand |journal=Marine Mammal Science |date=July 1989 |volume=5 |issue=3 |pages=213–227 |doi=10.1111/j.1748-7692.1989.tb00337.x }}</ref> In these same subspecies, a dark dorsal cape dims their tripartite color patterns.<ref name=Perrin1990/> Further offshore, subspecies tend to have a paler and less far-reaching cape.<ref>{{cite journal |last1=Perrin |first1=William F. |last2=Akin |first2=Priscilla A. |last3=Kashlwada |first3=Jerry V. |title=Geographic variation in external morpholoogy of the spinner dolphin Stenella longirostris in the eastern Pacific and implications for conservation |journal=Fishery Bulletin |volume=89 |issue=3 |year=1991 |pages=411–428 |url=https://spo.nmfs.noaa.gov/sites/default/files/pdf-content/1991/893/perrin.pdf }}</ref> In certain subspecies, some males may have upright fins that slant forward.<ref name=Perrin1990>{{cite journal |id={{INIST|19280231}} |last1=Perrin |first1=W. F |title=Subspecies of Stenellalongirostris (Mammalia: Cetacea: Delphinidae) |journal=Proceedings of the Biological Society of Washington |date=1990 |volume=103 |issue=2 |pages=453–463 }}</ref> Some populations of spinner dolphin found in the eastern Pacific have bizarre backwards-facing dorsal fins, and males can have strange humps and upturned [[Fish fin#AnchCaudal|caudal flukes]].<ref>{{cite news |last=Nelson |first=Bryan |title=Why does this dolphin have its fin on backwards? |date=20 November 2011 |url=http://www.mnn.com/earth-matters/animals/stories/why-does-this-dolphin-have-its-fin-on-backwards |url-status=dead |archive-url=https://web.archive.org/web/20111122060856/http://www.mnn.com/earth-matters/animals/stories/why-does-this-dolphin-have-its-fin-on-backwards |archive-date=22 November 2011 |work=Mother Nature Network }}</ref>

==Ecology==
The spinner dolphin lives in nearly all tropical and subtropical waters between [[40th parallel north|40°N]] and [[40th parallel south|40°S]].<ref>{{cite book |last1=Jefferson |first1=Thomas A. |last2=Leatherwood |first2=Stephen |last3=Webber |first3=Marc A. |title=Marine Mammals of the World |date=1993 |publisher=Food and Agriculture Organization of the United Nations |isbn=978-92-5-103292-3 }}{{pn|date=January 2022}}</ref> The species primarily inhabits coastal waters, islands, or banks. However, in the eastern tropical Pacific, spinner dolphins live far from shore.<ref>{{cite journal |last1=Au |first1=David W. K. |last2=Perryman |first2=Wayne L. |title=Dolphin habitats in the eastern tropical Pacific |journal=Fishery Bulletin |volume=83 |issue=4 |year=1985 |pages=623–643 |url=https://spo.nmfs.noaa.gov/sites/default/files/pdf-content/1985/834/au.pdf }}</ref> Spinner dolphins may use different habitats depending on the season.<ref>{{cite journal |last1=Fiedler |first1=Paul C. |last2=Reilly |first2=Stephen B. |title=Interannual variability of dolphin habitats in the eastern tropical Pacific. II: Effects on abundances estimated from tuna vessel sightings, 1975-1990 |journal=Fishery Bulletin |volume=92 |issue=2 |pages=451–463 |url=https://spo.nmfs.noaa.gov/sites/default/files/pdf-content/1994/922/fiedler.pdf }}</ref>

The spinner dolphin feeds mainly on small [[Mesopelagic zone|mesopelagic]] fish, squids, and [[Sergestidae|sergestid]] shrimps, and will dive 200–300 m to feed on them.<ref>{{cite journal |last1=Dolar |first1=M. Louella L. |last2=Walker |first2=William A. |last3=Kooyman |first3=Gerald L. |last4=Perrin |first4=William F. |title=Comparative feeding ecology of spinner dolphins (Stenella longirostris) and Fraser's dolphins (Lagenodelphis hosei) in the Sulu Sea |journal=Marine Mammal Science |date=January 2003 |volume=19 |issue=1 |pages=1–19 |doi=10.1111/j.1748-7692.2003.tb01089.x }}</ref> Spinner dolphins of Hawaii are nocturnal feeders and forage in deep scattering layers, which contain many species. The dwarf spinner dolphin may feed mostly on [[Benthic zone|benthic]] fish in reefs and shallow water.<ref name=Perrin1989/> Off Oahu, Hawaii, spinner dolphins forage at night and cooperatively herd their prey into highly dense patches.<ref name=Au>{{cite journal |last1=Benoit-Bird |first1=Kelly |last2=Au |first2=Whitlow |title=Hawaiian spinner dolphins aggregate midwater food resources through cooperative foraging |journal=The Journal of the Acoustical Society of America |date=1 October 2003 |volume=114 |issue=4 |pages=2300 |doi=10.1121/1.4780872 |bibcode=2003ASAJ..114.2300B }}</ref> They swim around the prey in a circle and a pair may swim through the circle to make a catch.<ref name=Au/> Spinner dolphins are in turn preyed on by sharks. Other possible predators include the [[killer whale]], the [[false killer whale]], the [[pygmy killer whale]] and the [[short-finned pilot whale]].<ref>{{cite book |editor1-last=Norris |editor1-first=Kenneth S. |editor2-last=Wursig |editor2-first=Bernd |editor3-last=Wells |editor3-first=Randall S. |editor4-last=Wursig |editor4-first=Melany |title=The Hawaiian Spinner Dolphin |date=1994 |publisher=University of California Press |isbn=978-0-520-91354-7 }}{{pn|date=January 2022}}</ref> They are susceptible to [[parasites]], and are known to exhibit both external ones like [[barnacle]]s and [[remora]]s, and internal ones, like [[nematode]]s, [[Trematoda|trematodes]], [[Cestoda|cestodes]] and [[acanthocephala]]ns.<ref name=Perrin/>

==Behavior and life history==

Due to the spinner dolphin foraging and feeding at night, in certain regions, such as Hawaii and northern Brazil, dolphins spend the daytime resting in shallow bays near deep water.<ref name=Wursig1994/><ref name=noaa>{{cite web|url=https://www.fisheries.noaa.gov/species/spinner-dolphin|publisher=Fisheries, N. O. A. A.|date=2021|title=Species directory: Spinner dolphin}}</ref> Spinner dolphins rest as a single unit, moving back and forth slowly in a tight formation but just out of contact with one another. These resting behaviors are observed for about four to five hours daily. During rest periods, spinner dolphins rely on vision rather than echolocation.<ref name=noaa/> At dusk, they travel offshore to feed. They travel along the shore during foraging trips, and the individuals that occupy the same bay may change daily.<ref name=Wursig1994>{{cite book |last1=Würsig |first1=Bernd |last2=Wells |first2=Randall S. |last3=Norris |first3=Kenneth S. |last4=Würsig |first4=Melany |chapter=A Spinner Dolphin's Day |pages=65–102 |chapter-url=https://books.google.com/books?id=k5kJje2spz8C&pg=PA65 |editor1-last=Norris |editor1-first=Kenneth S. |editor2-last=Wursig |editor2-first=Bernd |editor3-last=Wells |editor3-first=Randall S. |editor4-last=Wursig |editor4-first=Melany |title=The Hawaiian Spinner Dolphin |date=1994 |publisher=University of California Press |isbn=978-0-520-91354-7 }}</ref> Some individual dolphins do not always go to a bay to rest; however, in Hawaii, dolphins do seem to return to the same site each trip.<ref>{{cite journal |last1=Marten |first1=Ken |last2=Psarakos |first2=Suchi |title=Long-Term Site Fidelity and Possible Long-Term Associations of Wild Spinner Dolphins (''Stenella longirostris'') Seen Off Oahu, Hawaii1 |journal=Marine Mammal Science |date=1999 |volume=15 |issue=4 |pages=1329–1336 |doi=10.1111/j.1748-7692.1999.tb00894.x }}</ref>

Spinner dolphins live in an open and loose social organization.<ref name= Johnson1994>{{cite book |last1=Norris |first1=Kenneth S. |last2=Johnson |first2=Christine M. |chapter=Schools and Schooling |pages=232–242 |chapter-url=https://books.google.com/books?id=k5kJje2spz8C&pg=PA232 |editor1-last=Norris |editor1-first=Kenneth S. |editor2-last=Wursig |editor2-first=Bernd |editor3-last=Wells |editor3-first=Randall S. |editor4-last=Wursig |editor4-first=Melany |title=The Hawaiian Spinner Dolphin |date=1994 |publisher=University of California Press |isbn=978-0-520-91354-7 }}</ref> The spinner dolphins of Hawaii live in family groups, but also have associations with others beyond their groups.<ref name=Perrin/> Mothers and calves form strong social bonds. Spinner dolphins seem to have a promiscuous mating system, with individuals changing partners for up to some weeks. A dozen adult males may gather into coalitions.<ref name= Johnson1994/> Vocalizations of spinner dolphins include whistles, which may be used to organize the school, burst-pulse signals, and echolocation clicks.<ref>{{cite book |last1=Brownlee |first1=Shannon M. |last2=Norris |first2=Kenneth S. |chapter=The Acoustic Domain |pages=161–185 |chapter-url=https://books.google.com/books?id=k5kJje2spz8C&pg=PA161 |editor1-last=Norris |editor1-first=Kenneth S. |editor2-last=Wursig |editor2-first=Bernd |editor3-last=Wells |editor3-first=Randall S. |editor4-last=Wursig |editor4-first=Melany |title=The Hawaiian Spinner Dolphin |date=1994 |publisher=University of California Press |isbn=978-0-520-91354-7 }}</ref> The spinner dolphin has a 10-month gestation period, and mothers nurse their young for one to two years. Females are sexually mature at four to seven years, with three-year calving intervals, while males are sexually mature at seven to 10 years.<ref name=Perrin/> Spinner dolphins live for about 20-25 years old.<ref name=noaa/> Breeding is seasonal, more so in certain regions than others.<ref name=Perrin/>

Although most spinner dolphins are found in the deeper waters offshore of the islands, the rest of the Hawaiʻi population has a more coastal distribution. During daytime hours, the island-associated stocks of Hawaiian spinner dolphins seek sanctuary in nearshore waters, where they return to certain areas to socialize, rest, and nurture their young.{{Citation needed|date=December 2021}}

===Spinning behavior===
Spinner dolphins are known for their acrobatics and aerial behaviors. A spinner dolphin comes out of the water front first and twists its body as it rises into the air.<ref name=aerial>{{cite journal |last1=Fish |first1=Frank E. |last2=Nicastro |first2=Anthony J. |last3=Weihs |first3=Daniel |author3-link=Daniel Weihs |title=Dynamics of the aerial maneuvers of spinner dolphins |journal=Journal of Experimental Biology |date=15 February 2006 |volume=209 |issue=4 |pages=590–598 |doi=10.1242/jeb.02034 |pmid=16449554 |s2cid=3270054 |doi-access=free }}</ref> When it reaches its maximum height, the dolphin descends back into the water, landing on its side. A dolphin can make two to seven spins in one leap; the swimming and rotational speed of the dolphin as it spins underwater affects the number of spins it can do while airborne.<ref name=aerial/><ref name=noaa/> These spins may serve several functions. Some of these functions are believed by experts to be acoustic signaling or communication. Another reason is to remove ectoparasites such as remoras.<ref name=noaa/> Dolphins may also make nose-outs, tail slaps, flips, head slaps, "salmon leaps", and side and back slaps.<ref>{{Cite web|url=http://wilddolphin.org/behavior.html|title=Spinner Dolphin Behavior, pictures, Why do Spinner Dolphins Spin?|date=2005|website=wilddolphin.org|publisher=The Wild Dolphin Foundation|access-date=2017-11-19|quote=Spinning may also serve as a courtship display, or to eject water from the upper respiratory tract, reset organs of balance, help mix fluid in the gut and venous reservoirs, or simply be for fun. It might also be important to spinner dolphins' thermal budget since core and subcutaneous temperature are highest when the dolphins are spinning.}}</ref>

==Conservation status==
The protected status of spinner dolphins are CITES Appendix II and [[Marine Mammal Protection Act]] (MMPA) protected throughout its range as well as MMPA depleted in its eastern stock.<ref name=noaa/> Tens of thousands of spinner dolphins, mostly eastern and white-bellied varieties, were killed in the 30 years after [[Seine fishing|purse seine fishing]] for [[tuna]] began in the 1950s.<ref name=Perrin/> The process killed probably half of all eastern spinner dolphins. They have also been contaminated by pollutants such as [[DDT]] and [[Polychlorinated biphenyl|PCB]]s.<ref name=Perrin/> Spinner dolphins, as with other species affected by ETP tuna purse-seine fishing, are managed nationally by the coastal countries and internationally by the [[IATTC]]. The IATTC has imposed annual stock mortality limits on each purse seine and promulgated regulations regarding the safe release of dolphins.<ref name="iucn"/>

The eastern tropical Pacific and Southeast Asian populations of the spinner dolphin are listed on Appendix II<ref name="Appendices">"[http://www.cms.int/documents/appendix/Appendices_COP9_E.pdf Appendix II] {{webarchive|url=https://web.archive.org/web/20110611112003/http://www.cms.int/documents/appendix/Appendices_COP9_E.pdf |date=11 June 2011 }}" of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). As amended by the Conference of the Parties in 1985, 1988, 1991, 1994, 1997, 1999, 2002, 2005 and 2008. Effective: 5 March 2009.</ref> of the Convention on the Conservation of Migratory Species of Wild Animals ([[Bonn Convention|CMS]]), since they have an unfavourable conservation status or would benefit significantly from international co-operation organized by tailored agreements.<ref>{{cite web|url=http://www.cms.int/reports/small_cetaceans/data/S_longirostris/s_longirostris.htm|title=Convention on Migratory Species page on the Spinner dolphin|website=cms.int|access-date=31 August 2011|archive-date=22 March 2012|archive-url=https://web.archive.org/web/20120322123712/http://www.cms.int/reports/small_cetaceans/data/S_longirostris/s_longirostris.htm|url-status=dead}}</ref>

In addition, the spinner dolphin is covered by Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region ([[Pacific Islands Cetaceans Memorandum of Understanding|Pacific Cetaceans MoU]])<ref>{{cite web|url=http://www.pacificcetaceans.org/|title=Pacific Cetaceans - Convention on Migratory Species|website=Pacific Cetaceans}}</ref> and the Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia ([[West African Aquatic Mammals Memorandum of Understanding|Western African Aquatic Mammals MoU]]). Spinner dolphins are susceptible to disease and two of the recorded diseases within them are toxoplasmosis and cetacean morbillivirus. The number of cases reported however is fairly low in the species.<ref name=noaa/>

Spinner dolphins in Hawaii receive multiple daily visits to their near-shore resting grounds, with boats taking people out daily to snorkel and interact with the local dolphin population. Such activities are increasingly coming under criticism on the grounds of possible harm to the dolphins,<ref>{{Cite web | url=http://www.fpir.noaa.gov/PRD/prd_swim_with_wild_dolphins.html | title=Home page of NOAA Fisheries Service - Pacific Islands Regional Office| date=12 November 2021}}</ref> and efforts are being made both to educate the public in order to minimise human impact on the dolphins, and to bring in regulations to govern these activities.<ref>{{cite web|url=http://www.halekeokeo.com/pgs/dolphins.php|title=Spinner Dolphins of Kealakekua Bay|website=www.halekeokeo.com|access-date=3 December 2014|archive-date=17 November 2014|archive-url=https://web.archive.org/web/20141117160408/http://halekeokeo.com/pgs/dolphins.php|url-status=dead}}</ref>

In 2023, 33 swimmers were arrested for reportedly harassing dolphins off the coast of the Big Island of Hawaii. The swimmers reportedly broke federal law by swimming within 45 meters (50 yards) of the dolphins. The ban went into effect in 2021 due to dolphins not getting enough rest during the day to forage for food at night. The swimmers were caught by drone footage pursuing the dolphins as they tried to escape.<ref>{{cite web|url=https://apnews.com/article/hawaii-swimmers-harassing-dolphins-illegal-64fce5e944d575644406d75323ca8082|title=Hawaii authorities say 33 swimmers were harassing dolphins|website=AP News}}</ref>

==Images==
<gallery widths="200px" heights="150px">
File:Spinners.png|Spinner dolphins at [[Ras Samadai]]
File:A_pod_of_spinner_dolphins_in_the_Red_Sea.jpg|A pod of spinner dolphins in the [[Red Sea]]
File:Spinner_Dolphin_Indian_Ocean_07-2017.jpg|Spinner Dolphin in the Indian Ocean
File:Spinner_Dolphin_Alphonse_Atoll_07-2017.jpg|Spinner Dolphin at Alphonse Atoll
File:SpinnerDolphinsoffKauai 1999-03-15.jpg|A pod of spinner dolphins in [[Kauai]], Hawaii
File:Stenella longirostris Lanai Hawaii.jpg|Spinner dolphin at [[Lanai]] Hawaii
File:twist tail spin.jpg|Hawaiian spinner dolphin spinning
File:Spinner Dolphin at midway.jpg|Spinner dolphin at [[Midway Atoll]]
File:Spinner dolphins video.wmv.OGG|Spinner dolphins video taken at Midway Atoll
File:Spinner dolphins (6741930935).jpg|[[Cetacean surfacing behavior|Porpoising]] in [[Papahānaumokuākea Marine National Monument]]
File:Spinner dolphins Kauai Hawaii (31339186057).jpg|Spinner dolphins next to Kauai, Hawaii
</gallery>

==See also==
{{Portal|Cetaceans|Mammals|Marine life}}
*[[List of cetaceans]]
*[[Marine biology]]

==References==
{{Reflist|30em}}

==External links==
{{Commons|stenella longirostris}}
*[http://www.wilddolphin.org/spinner.html Hawaiian Spinner Dolphins]
*[http://www.alphonse-island.com/en/blog/2016/06/spinner-dolphins-stenella-longirostris Spinner Dolphins in the Seychelles]
*[http://www.robertosozzani.it/Delfini/cont.html Red Sea Spinner Dolphins]
*[http://www.livescience.com/animalworld/060327_mm_dolphin_spin.html LiveScience - How Dolphins Spin, and Why]
*[https://web.archive.org/web/20070409164145/http://bluevoice.org/sections/dolphins/spin.shtml BlueVoice.org - The World of Spinner Dolphins]
*[http://www.wdcs.org: Whale and Dolphin Conservation Society]
*[http://cetus.ucsd.edu/voicesinthesea_org/species/dolphins/spinner.html Voices in the Sea - Sounds of the Spinner Dolphin]

{{Cetacea|O.}}

{{Taxonbar|from=Q649513}}
{{Authority control}}

[[Category:Stenella|spinner dolphin]]
[[Category:Cetaceans of the Atlantic Ocean]]
[[Category:Cetaceans of the Indian Ocean]]
[[Category:Cetaceans of the Pacific Ocean]]
[[Category:Pantropical fauna]]
[[Category:Mammals described in 1828|spinner dolphin]]
[[Category:Taxa named by John Edward Gray|spinner dolphin]]
[[Category:Articles containing video clips]]

Spinner dolphin - Revision history

Ajay Kumar: Created a new article