View source for Common dolphin

{{Short description|Species of mammal}}
{{For|the ray-finned fish known as the common dolphinfish|Mahi-mahi}}
{{More citations needed|date=August 2025}}
{{Speciesbox
| name = Common dolphin
| image = Common dolphin noaa.jpg
| image_caption = <small>Common dolphins doing a behavior known as "porpoising."</small>
| image2 = Common dolphin size.svg
| image2_caption = Size compared to an average human
| status = LC
| status_system = IUCN3.1
| status_ref = <ref name="iucn status 19 November 2021">{{cite iucn |author=Braulik, G. |author2=Jefferson, T.A. |author3=Bearzi, G. |date=2021 |title=''Delphinus delphis'' |volume=2021 |article-number=e.T134817215A199893039 |doi=10.2305/IUCN.UK.2021-2.RLTS.T134817215A199893039.en |access-date=19 November 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 = Delphinus
| species = delphis
| authority = [[Carl Linnaeus|Linnaeus]], [[10th edition of Systema Naturae|1758]]
| parent_authority = [[Carl Linnaeus|Linnaeus]], [[10th edition of Systema Naturae|1758]]
| subdivision_ranks = Subspecies
| subdivision = *''D. d. delphis'' 
*''D. d. bairdii''
*''D. d. ponticus''
* ''D. d. tropicalis''
| range_map = Delphinus delphis map.svg
| range_map_caption = {{legend2|#5599ffff|Range of common dolphin|outline=gray}}
| synonyms = {{collapsible list|
* ''Delphinus albimanus'' Peale, 1848
* ''Delphinus algeriensis'' Loche, 1860
* ''Delphinus capensis'' Gray, 1828
* ''Delphinus delphus'' Linnaeus, 1758
* ''Delphinus forsteri'' Gray, 1846
* ''Delphinus fulvifasciatus'' Wagner, 1846
* ''Delphinus fulvofasciatus'' True, 1889
* ''Delphinus janira'' Gray, 1846
* ''Delphinus loriger'' Wiegmann, 1846
* ''Delphinus marginatus'' Lafont, 1868
* ''Delphinus novaezealandiae'' Gray, 1850
* ''Delphinus novaezeelandiae'' Wagner, 1846
* ''Delphinus novaezelandiae'' Quoy & Gaimard, 1830
* ''Delphinus vulgaris'' Lacépède, 1804
* ''Delphinus zelandae'' Gray, 1853
}}
}}

The '''common dolphin''' ('''''Delphinus delphis''''') is the most abundant [[cetacean]] in the world, with an estimated global [[population]] of about six million.<ref>Hammond, P.S., Bearzi, G., Bjørge, A., Forney, K., Karczmarski, L., Kasuya, T., Perrin, W.F., Scott, M.D., Wang, J.Y., Wells, R.S. & Wilson, B. 2008. ''Delphinus delphis''. ''The IUCN Red List of Threatened Species'' 2008: e.T6336A12649851. {{doi|10.2305/IUCN.UK.2008.RLTS.T6336A12649851.en}}. Downloaded on 10 July 2020.</ref> It is currently the [[Monotypic taxon|only member]] of the genus '''''Delphinus''''', the [[type genus]] of the subfamily [[Delphininae]]. This places it as a close relative of the [[bottlenose dolphin]], [[humpback dolphin]], [[striped dolphin]], [[spinner dolphin]], [[Clymene dolphin]], [[spotted dolphin]], [[Fraser's dolphin]], the [[tucuxi]], and the [[Guiana dolphin]].<ref>{{Cite journal|last1=Amaral|first1=Ana R.|last2=Jackson|first2=Jennifer A.|last3=Möller|first3=Luciana M.|last4=Beheregaray|first4=Luciano B.|last5=Manuela Coelho|first5=M.|date=2012-07-01|title=Species tree of a recent radiation: The subfamily Delphininae (Cetacea, Mammalia)|url=http://www.sciencedirect.com/science/article/pii/S105579031200142X|journal=Molecular Phylogenetics and Evolution|language=en|volume=64|issue=1|pages=243–253|doi=10.1016/j.ympev.2012.04.004|pmid=22503758|bibcode=2012MolPE..64..243A |issn=1055-7903|url-access=subscription}}</ref>

The common dolphin was once divided into two different species, the '''short-beaked common dolphin''' and the '''long-beaked common dolphin'''. These are now generally regarded as [[ecotype]]s. Recent research shows that many long-beaked populations worldwide are not closely related to one another, often originating from short-beaked ancestors, and they do not consistently share the same derived traits. For this reason, these [[Polymorphism (biology)|forms]] are no longer classified as separate species.<ref>{{Cite web|url=https://us.whales.org/whales-dolphins/species-guide/long-beaked-common-dolphin/|title=Long-beaked common dolphin|access-date=2020-07-10|archive-date=2023-03-21|archive-url=https://web.archive.org/web/20230321071639/https://us.whales.org/whales-dolphins/species-guide/long-beaked-common-dolphin/}}</ref>

Despite its name, the common dolphin is not widely considered the "[[Archetype|archetypal]]" dolphin; that role is more often associated with the bottlenose dolphin, largely because of its frequent appearances in [[Dolphinarium|aquaria]] and [[Mass media|the media]].{{Clarify|reason=Another reason may be that bottlenose dolphins are more coastal?|date=August 2025}} Nevertheless, the common dolphin held cultural significance in antiquity and frequently appeared in [[Ancient Greece|Greek]] and [[Ancient Rome|Roman]] art, such as in murals created by the [[Minoan civilization]].<ref>{{Cite web |url=http://www.teachgreece.org/Study_Guides/Mural_Painting/downloadable_docs/MinoanMurals.pdf |title=Archived copy |access-date=2020-07-10 |archive-date=2012-01-31 |archive-url=https://web.archive.org/web/20120131123253/http://www.teachgreece.org/Study_Guides/Mural_Painting/downloadable_docs/MinoanMurals.pdf }}</ref>

==Physical characteristics==
Common dolphin are medium-sized dolphins; adults range between {{convert|1.9|and|2.5|m|ft|abbr=on}} long, and can weigh between {{convert|80|-|235|kg|abbr=on|lb}}, although the range between {{convert|80|-|150|kg|abbr=on|lb}} is more common.<ref name=princeton>{{cite book|title=Whales, Dolphins and Other Marine Mammals of the World|author1=Shirihai, H.  |author2=Jarrett, B.|year=2006|pages=171–176|publisher=Princeton University Press |isbn=0-691-12757-3}}</ref>  Males are generally longer and heavier.<ref name=princeton/> The [[Animal coloration|dolphin's coloration]] is unusual, with a dark back and white belly ([[countershading]]), while on each side is an [[hourglass]] pattern colored light grey, yellow, or gold in front and dirty grey in back.<ref name=Audubon>{{cite book|year=2002|title=Guide to Marine Mammals of the World|author1=Reeves, Stewart|author2=Clapham, Powell|page=[https://archive.org/details/guidetomarinemam00folk/page/388 388]|publisher=Knopf Doubleday Publishing |isbn=0-375-41141-0|url-access=registration|url=https://archive.org/details/guidetomarinemam00folk/page/388}}</ref> They have long, thin [[Rostrum (anatomy)|rostra]] with up to 50–60 small, sharp, interlocking teeth on each side of each jaw.<ref name="TheCommon">{{cite web |title=The Common Dolphin |url=http://library.thinkquest.org/17963/genus-Delphinus.html |access-date=2008-07-03 |archive-url=https://web.archive.org/web/20080619125912/http://library.thinkquest.org/17963/genus-Delphinus.html |archive-date=2008-06-19 }}</ref>

==Taxonomy==
[[File:Common Dolphin.jpg|thumb|left|"Short-beaked" common dolphin, Ireland]]
Despite the historic practice of [[lumping]] the entire genus ''Delphinus'' into a single species, these widely distributed dolphins exhibit [[Polymorphism (biology)|a wide variety]] of sizes, shapes and colors. Indeed, over the past few decades, over 20 distinct species in the genus have been proposed. Scientists in California in the 1960s concluded there were two species&nbsp;— the long-beaked and short-beaked. The long-beaked common dolphin was thought to have a disjointed [[Species distribution|range]] in [[Marine coastal ecosystem|coastal areas]] in tropical and warmer temperate oceans; this range included parts of western and southern [[Africa]], much of western [[South America]], central [[California]] to central [[Mexico]], coastal [[Peru]], the seas around [[Japan]], [[Korea]] and [[Taiwan]], and possibly near [[Oman]].<ref name=encyc/> [[Vagrancy (biology)|Vagrants]] have been recorded as far north as [[Vancouver Island]].
[[File:Delphinus capensis.JPG|thumb|"Long-beaked" common dolphin, California]]
This analysis was seemingly confirmed by a more in-depth [[genetic study]] in the 1990s. This study also suggested a third species (''D. tropicalis'', common name Arabian common dolphin or Indo-Pacific common dolphin), characterized by an extremely long and thin beak and found in the [[Red Sea]] and [[Indian Ocean]], might be distinguished from the long-beaked species. 

Recent evidence has demonstrated that different populations of long-beaked common dolphins around the world are not closely related to one another and are often descendant from a short-beaked ancestor (as well as not sharing common [[derived character]]s). Therefore, all long-beaked and short-beaked common dolphin populations are currently listed as the same species; they are all subspecies of ''Delphinus delphis''.<ref name="Handbook">{{Cite web|last=Handbook|first=Whale Watching|date=2020-07-10|title=Common Dolphin|url=https://wwhandbook.iwc.int/en/species/common-dolphin|access-date=2020-07-10|website=Whale Watching Handbook|language=en}}</ref><ref>{{Cite journal|last1=Cunha|first1=Haydée A.|last2=Castro|first2=Rocio Loizaga de|last3=Secchi|first3=Eduardo R.|last4=Crespo|first4=Enrique A.|last5=Lailson-Brito|first5=José|last6=Azevedo|first6=Alexandre F.|last7=Lazoski|first7=Cristiano|last8=Solé-Cava|first8=Antonio M.|date=2015-11-11|title=Molecular and Morphological Differentiation of Common Dolphins (Delphinus sp.) in the Southwestern Atlantic: Testing the Two Species Hypothesis in Sympatry|journal=PLOS ONE|language=en|volume=10|issue=11|article-number=e0140251|doi=10.1371/journal.pone.0140251|issn=1932-6203|pmc=4641715|pmid=26559411|bibcode=2015PLoSO..1040251C |doi-access=free}}</ref><ref>{{Cite journal|last1=McGowen|first1=Michael R|last2=Tsagkogeorga|first2=Georgia|last3=Álvarez-Carretero|first3=Sandra|last4=dos Reis|first4=Mario|last5=Struebig|first5=Monika|last6=Deaville|first6=Robert|last7=Jepson|first7=Paul D|last8=Jarman|first8=Simon|last9=Polanowski|first9=Andrea|last10=Morin|first10=Phillip A|last11=Rossiter|first11=Stephen J|date=2019-10-21|title=Phylogenomic Resolution of the Cetacean Tree of Life Using Target Sequence Capture|journal=Systematic Biology|volume=69|issue=3|pages=479–501|doi=10.1093/sysbio/syz068|issn=1063-5157|pmc=7164366|pmid=31633766}}</ref> Currently, the common dolphin is divided into four subspecies:<ref name="Handbook" /><ref name="mammalogy">{{cite web |url=https://www.marinemammalscience.org/species-information/list-marine-mammal-species-subspecies/|title=List of Marine Mammal Species and Subspecies{{!}}May 2022 |date=13 November 2016 |publisher=[[Society for Marine Mammalogy]] |access-date=1 May 2022}}</ref>
*''D. d. delphis'', the [[nominate subspecies]]
*''D. d. bairdii'', the  Eastern North Pacific long-beaked common dolphin (sometimes elevated to full species)<ref>{{Cite journal |last1=Jefferson |first1=Thomas A. |last2=Archer |first2=Frederick I. |last3=Robertson |first3=Kelly M. |date=2024-04-30 |title=The long-beaked common dolphin of the eastern Pacific Ocean: Taxonomic status and redescription of Delphinus bairdii |journal=Marine Mammal Science |volume=40 |issue=4 |article-number=e13133 |language=en |doi=10.1111/mms.13133 |issn=0824-0469|doi-access=free |bibcode=2024MMamS..40E3133J }}</ref>
*''D. d. ponticus'', the [[Black Sea]] common dolphin
*''D. d. tropicalis'', the Arabian or Indo-Pacific common dolphin

===Fossil record===
Many [[Extinction|extinct]] cetacean species were once lumped into ''Delphinus'', but have since been moved to other genera. In the late 19th century several fossil species were described as part of this genus, such as ''Delphinus baltringii'', ''Delphinus delannoy'' and ''Delphinus domeykoi''. However, these species are no longer considered [[Valid name (zoology)|valid]].<ref>{{cite journal |last1=Gutstein |first1=Carolina |title=Cetáceos fósiles de Chile: Contexto evolutivo y paleobiogeográfico |journal=Publicación Ocasional del Museo Nacional de Historia Natural, Chile |date=2015 |volume=63 |pages=339–383}}</ref> Another species known as ''Delphinus brevidens'' was reassigned to the genus ''Stereodelphis'', now generally considered [[Synonym (taxonomy)|synonymous]] with ''[[Squalodon]]''.<ref>{{cite book |title=Proceedings of the United States National Museum: Volume 62 |date=1923 |publisher=Smithsonian Institution Press |page=10}}</ref>

==Biology==
Common dolphins live in both warm-temperate and tropical waters ranging from [[40th parallel north|40]]–[[60th parallel north|60°N]] to [[50th parallel south|50°S]]. Long-beaked common dolphins mostly inhabit shallow, warm coastal water.<ref name=encyc/> Short-beaked common dolphins are common "along [[Shelf-edge canyon|shelf edges]] and in areas with sharp bottom relief such as [[seamount]]s and [[escarpment]]s".<ref name="Audubon"/> In general, they are a widely distributed species. They can be found around the world in both offshore and coastal waters. In the Northwest Atlantic, they can be found from [[Cape Hatteras]] to [[Newfoundland (island)|Newfoundland]] and are strongly associated with the [[Gulf Stream]]. Dolphins in this region can often be found in areas that have certain geological factors like underwater canyons and ridges because this is where up-welling occurs which result in greater nutrients. In the Eastern Pacific, common dolphins are found along the coast of California and are associated with the California current. Short-beaked common dolphins can also be found in Europe, particularly the [[Scotian Shelf]], the [[Black Sea]] and [[the Mediterranean]]. In the [[Southern Hemisphere]], they are abundant in the southwestern Pacific, around New Zealand and [[southern Australia]]. They are generally a [[Pelagic zone|pelagic]] species that are often found in waters {{convert|650|–|6500|ft|abbr=in}} deep, with the short-beaked type preferring deeper waters than the long-beaked type<ref name="Chavez-Rosales 5833">{{Cite journal|last1=Chavez-Rosales|first1=Samuel|last2=Palka|first2=Debra L.|last3=Garrison|first3=Lance P.|last4=Josephson|first4=Elizabeth A.|date=December 2019|title=Environmental predictors of habitat suitability and occurrence of cetaceans in the western North Atlantic Ocean|journal=Scientific Reports|language=en|volume=9|issue=1|page=5833|doi=10.1038/s41598-019-42288-6|issn=2045-2322|pmc = 6456503|pmid=30967576|bibcode=2019NatSR...9.5833C }}</ref> Temperature also plays a large role in the congregation of dolphins. For example, in the western North Atlantic, almost all sightings of common dolphins took place in waters from {{convert|16|to|20|C|abbr=on}}. However, common dolphins were sighted in waters as cold as {{convert|5|C|abbr=on}}.<ref name="Chavez-Rosales 5833"/>
===Sociality===
[[File:CD 3.jpg|thumb|left|Common dolphins [[wikt:porpoising|porpoising]], Ireland]]
Common dolphins can live in [[Sociality|aggregations]] or "pods" of hundreds or even thousands of dolphins.<ref name="encyc">{{cite book|title=Encyclopedia of Marine Mammals|author=Perrin, W.|chapter=Common Dolphins|editor1=Perrin, W.|editor2=Wursig, B.|editor3=Thewissen, J.|pages=[https://archive.org/details/encyclopediaofma2002unse/page/245 245–248]|year=2002|publisher=Academic Press|isbn=978-0-12-551340-1|chapter-url=https://archive.org/details/encyclopediaofma2002unse/page/245}}</ref> Common dolphins are often seen in groups numbering several hundred individuals (with subgroups consisting of 20–30 individuals). Occasionally, different groups will come together to form mega-pods which can consist of over 10,000 dolphins. Genetic studies in the Northeast Atlantic suggest that common dolphin pods generally do not consist of close kin, but rather of members that are not closely related. Unlike many delphinids, common dolphins do not live in a [[matriarchal society]]. That being said, closely related individuals are usually found in similar geographical locations fairly consistently, providing evidence that this species displays [[site fidelity]] (at least in the Northeastern Atlantic). Male common dolphins display greater site fidelity in relation to their kin than females.<ref>{{Cite journal|last1=Ball|first1=Laura|last2=Shreves|first2=Kypher|last3=Pilot|first3=Małgorzata|last4=Moura|first4=André E.|date=2017-07-21|title=Temporal and geographic patterns of kinship structure in common dolphins (Delphinus delphis) suggest site fidelity and female-biased long-distance dispersal|journal=Behavioral Ecology and Sociobiology|language=en|volume=71|issue=8|page=123|doi=10.1007/s00265-017-2351-z|issn=1432-0762|pmc=5522516|pmid=28794579|bibcode=2017BEcoS..71..123B }}</ref> Common dolphin pod structure often consists of nursery pods (which includes females and calves), [[Bachelor herd|bachelor pods]] (consisting of all males) and mixed groups of males and females, including sub-adults and calves. Genetic evidence seems to indicate that common dolphins live in [[fission-fusion societies]], where dolphins form pods that are not necessarily stable and do not necessarily consist of related individuals. It is not known if common dolphins form lifelong bonds with other individuals like the long-term male alliances seen in bottlenose dolphins.<ref>{{Cite journal|last1=Viricel|first1=Amélia|last2=Strand|first2=Allan E.|last3=Rosel|first3=Patricia E.|last4=Ridoux|first4=Vincent|last5=Garcia|first5=Pascale|date=December 2008|title=Insights on common dolphin (Delphinus delphis) social organization from genetic analysis of a mass-stranded pod|journal=Behavioral Ecology and Sociobiology|language=en|volume=63|issue=2|pages=173–185|doi=10.1007/s00265-008-0648-7|bibcode=2008BEcoS..63..173V |s2cid=25991354|issn=0340-5443}}</ref>

There is some evidence that common dolphins use signature whistles, similar to that of the bottlenose dolphin. These whistles are believed to serve as an acoustic label, and provide identification information similar to that of a name. &nbsp;It takes approximately 1 year for a calf to learn its signature whistle after which it remains stable for the rest of a dolphin's life. Off [[South Africa]], as many as 29 common dolphin signature whistle types were detected. However, it was difficult to determine if each dolphin had its own signature whistle due to the vast number of dolphins present (over 1,000) and [[Noise pollution#Marine life|anthropogenic background noise]]. Additionally, considering the vast number of dolphins present and&nbsp; taking into account their feeding and diving behavior, it appears that common dolphin signature whistles are also used for group cohesion. Another hypothesis for the function of signature whistles is that they serve as a beacon for lost individuals.<ref>{{Cite journal|last1=Fearey|first1=J.|last2=Elwen|first2=S. H.|last3=James|first3=B. S.|last4=Gridley|first4=T.|date=September 2019|title=Identification of potential signature whistles from free-ranging common dolphins (Delphinus delphis) in South Africa|journal=Animal Cognition|language=en|volume=22|issue=5|pages=777–789|doi=10.1007/s10071-019-01274-1|pmid=31177344|s2cid=176078258|issn=1435-9448|hdl=2263/70689|hdl-access=free}}</ref>
===Interspecific relations===
Common dolphins sometimes associate with other dolphin species, such as [[pilot whale]]s.<ref name="encyc" />  In the [[Gulf of Corinth]], common dolphins frequently display mixed species association, especially with [[Striped dolphin|striped]] and [[Risso's dolphin]]s.<ref>{{Cite journal|last1=Neumann|first1=Dirk R.|last2=Orams|first2=Mark B.|date=2003-01-01|title=Feeding behaviours of short-beaked common dolphins, ''Delphinus delphis'', in New Zealand|journal=Aquatic Mammals|volume=29|issue=1|pages=137–149|doi=10.1578/016754203101023997|bibcode=2003AqMam..29..137N |issn=0167-5427}}</ref> Over one third of all dolphin sightings in this Gulf consisted of mixed species associations that partially consisted of common dolphins. In mixed species associations, the ratio of striped to common dolphins ranged from 6:1 to 11:1. When Risso's dolphins were present (there would usually be only one or two individuals), it appeared that many of their scars were the result of interactions with striped and [[spinner dolphin]]s. In many of the interactions, the Risso's dolphins would chase and herd the common dolphins toward the boat, while the common dolphins would try and swim under the Risso's dolphins. When groups of common and striped dolphins would charge at each other, the Risso's dolphin would chase the striped dolphins. Sometimes these interactions appeared to be [[Animal play|playful]], and at other times [[Agonistic behaviour|aggressive]]. Synchronized swimming and surfacing were commonly observed. These interactions take place in the deepest part of the Gulf, furthest from shore, and usually consist of a total of about 60 dolphins from all three species.

There have been confirmed cases of [[Hybrid (biology)|hybridization]] between striped and common dolphins in this region, with 15 confirmed cases of such hybrids. [[Genetic analysis|Genetic]] and observational evidence has demonstrated that the hybrids are fertile and are capable of not only reproducing with other hybrids, but are capable of reproducing with each of the parent species.<ref>{{Cite journal|last1=Antoniou|first1=Aglaia|last2=Frantzis|date=2018|title=Evidence of introgressive hybridization between Stenella coeruleoabla and Delphinus delphis in the Greek Seas|journal=Molecular Phylogenetics and Evolution|volume=129|pages=325–337|doi=10.1016/j.ympev.2018.09.007|pmid=30218775|bibcode=2018MolPE.129..325A |s2cid=52279448 }}</ref> Striped dolphins have been known to mate with other dolphins, as the [[Clymene dolphin]] is the result of hybrid speciation between striped and spinner dolphins. However, this{{Vague|reason=This what?|date=August 2025}} is unlikely to happen with common dolphins, as their population in the Gulf of Corinth is too low.<ref>{{Cite journal|last=Aglaia|first=Antoniou|date=2018|title=Evidence of introgressive hybridization between Stenella coeruleoabla and Delphinus delphis in the Greek Seas.|journal=Molecular Phylogenetics and Evolution|volume=129|pages=325–337|doi=10.1016/j.ympev.2018.09.007|pmid=30218775|bibcode=2018MolPE.129..325A |s2cid=52279448 }}</ref> There is one confirmed case of a wild hybrid between a bottlenose and common dolphin in southern Spain, an important feeding ground for both species. The mother was a female bottlenose dolphin (dubbed Billie) who had spent 10 years in a common dolphin pod. Billie was observed assisting common calves reach the surface three different times and would babysit the calves after the mother went through labor. The length of the calf was similar to that of a bottlenose dolphin calf, with the lateral stripes and coloration of a common dolphin. The calf was seen with its mother almost daily on dolphin-watching tours among a nursery pod of common dolphins which also contained some immature striped dolphins. Sightings of the calf took place when temperatures were between {{convert|14|and|26|C|abbr=on}}. The calf was mainly observed swimming alongside the mother and was seen rubbing its head on its mother, jumping backwards over its mother and engaging in flipper-to flipper, belly-to flipper and belly-to belly contact.<ref>{{Cite journal|last1=Espada|first1=Rocío|last2=Olaya-Ponzone|first2=Liliana|last3=Haasova|first3=Luisa|last4=Martín|first4=Estefanía|last5=García-Gómez|first5=José C.|date=2019-04-16|title=Hybridization in the wild between Tursiops truncatus (Montagu 1821) and Delphinus delphis (Linnaeus 1758)|journal=PLOS ONE|volume=14|issue=4|article-number=e0215020|doi=10.1371/journal.pone.0215020|issn=1932-6203|pmc=6467441|pmid=30990845|bibcode=2019PLoSO..1415020E |doi-access=free}}</ref> Common dolphins and bottlenose dolphins are also known to interbreed in captivity.<ref name="encyc" /> One of these hybrids has been bred back to a bottlenose dolphin, demonstrating such hybrids are fertile.<ref name="hybrid" /> 

Common dolphins have been observed [[bow riding]] on both [[baleen whale]]s and boats.<ref name="encyc" /> They are fast swimmers, and [[Whale surfacing behaviour|breaching]] behavior and aerial acrobatics are common with this species.<ref name="princeton" /> They are known to display [[altruistic behavior]]s to support injured members.<ref>Walker M. (2013-01-28). [https://archive.today/20140523175300/http://www.bbc.co.uk/nature/21146455 Dolphins try to save dying companion]. [[BBC Natural History Unit|BBC Nature News]]. retrieved on 24-05-2014</ref><ref>{{cite journal|doi=10.1111/mms.12012|title=An unusual case of care-giving behavior in wild long-beaked common dolphins (''Delphinus capensis'') in the East Sea|journal=Marine Mammal Science|pages=E508–E514|volume=29|issue=4|year=2012|last1=Park|first1=Kyum J.|last2=Sohn|first2=Hawsun|last3=An|first3=Yong R.|last4=Moon|first4=Dae Y.|last5=Choi|first5=Seok G.|last6=An|first6=Doo H.}}</ref>

Common dolphins have a varied diet consisting of many species of [[Piscivore|fish]] and [[squid]]. This includes both [[mesopelagic]] species and [[epipelagic]] schooling species. They have been recorded to make dives up to {{Convert|200|m|ft}} deep.
===Reproduction===
The short-beaked common dolphin has a [[gestation period]] of 10 to 11 months.<ref name="encyc" />  The newborn calf has a length of {{Convert|70|to|100|cm|ft|lk=on}} and weighs about {{Convert|10|kg|lb}}.<ref name="princeton" />  For the [[Black Sea]] population, [[weaning]] occurs at between five and six months, but occurs later (up to about 19 months) in other areas.<ref name="princeton" /><ref name="encyc" />  Typical interbirth interval ranges from one year for the Black Sea population to three years for eastern [[Pacific Ocean]] populations.<ref name="encyc" />  Age of [[sexual maturity]] also varies by location, but can range between 2 and 7 years for females and 3 and 12 years for males.<ref name="princeton" /><ref name="encyc" /> No evidence exists of any major reproductive differences between the two forms.<ref name="Audubon" />

==Relation to humans==

===Captivity===
Common dolphins are not common in captivity. Despite this, on multiple occasions, a beached common dolphin in California was nursed back to health at [[SeaWorld San Diego]], but deemed unfit to release back to the ocean. These common dolphins remained at SeaWorld with the bottlenose dolphin exhibit. On one occasion, a male common dolphin managed to impregnate one of the female bottlenose dolphins in the exhibit, leading to four hybrid births.<ref name="hybrid">{{cite journal|title=Captive-born bottlenose dolphin × common dolphin (''Tursiops truncatus'' × ''Delphinus capensis'') intergeneric hybrids|author1=Zornetzer H.R. |author2=Duffield D.A. |journal=Canadian Journal of Zoology |volume=81 |issue=10 |pages=1755–1762 |date=October 1, 2003|doi=10.1139/z03-150|bibcode=2003CaJZ...81.1755Z }}</ref> One of the resulting common dolphin/bottlenose dolphin hybrids remained at SeaWorld, San Diego (alternately under the name Cindy or Bullet) while the other (named CJ) was kept at [[Discovery Cove]], and was moved to SeaWorld Orlando in 2016. In 2024, the species returned to SeaWorld San Diego after a pair of rescued common dolphins were stranded on local beaches. Despite serious injuries and malnutrition, both survived, and due to their young age and necessary recovery they were deemed unreleasable. They were named Cardiff and Chance and now reside permanently at the park.<ref>{{cite web | url= https://www.cbs8.com/article/news/local/dolphins-chance-and-cardiff-and-two-new-calves-join-seaworld/509-c797afe3-32c2-4cee-a035-5db119c14f99 | title=New dolphin calves spark joy at SeaWorld San Diego | website=CBS8 San Diego | date=10 June 2025 | access-date=September 27, 2025}}</ref>

Other than at SeaWorld, at least 90 common dolphins are known to have been captured from the wild and kept in captivity. Captured common dolphins are said to be difficult to keep in captivity.<ref name="TheCommon" />

The behavior of captive common dolphins is not very well studied. However, a study was conducted in New Zealand of common dolphin reacting to swimmers at [[Marineland of New Zealand]].<ref>{{Cite journal |date=2003 |title=Behavioural responses of captive common dolphins Delphinus delphis to a 'Swim-with-Dolphin' programme |journal=Applied Animal Behaviour Science}}</ref> Unlike bottlenose dolphins (which demonstrated antagonistic or sexual behaviors), the common dolphins retreated to the refuge center of the pool, where swimmers were not allowed. They did not leave the refuge section until the swimmers left. The dolphins also surfaced much more frequently, which is a possible indicator of stress. Aggressive and playful behavior among the dolphins decreased when swimmers were present. This behavior is consistent with wild common dolphins off of New Zealand, as they actively avoid swimmers.<ref>{{Cite journal|last=Kyngdon|first=D.|date=2003|title=Behavioural responses of captive common dolphins Delphinus delphis to a 'Swim-with-Dolphin' programme.|journal=Applied Animal Behaviour Science|volume=81|issue=2|pages=163–170|doi=10.1016/S0168-1591(02)00255-1}}</ref>
=== Mass stranding events ===
On June 8, 2009, a [[Cetacean stranding|mass-stranding event]] (MSE) occurred in [[Falmouth Bay]], [[Cornwall]], United Kingdom. It is believed the MSE was likely caused by naval involvement,{{Clarify|date=August 2025}} as all other factors which cause MSEs in cetaceans appear unlikely to have influenced the event. During the event, 26 common dolphins washed ashore, and about the same number floated back out to sea. There were three other MSEs in the UK before this event, all of unknown cause, from the years 1915 to 1938, but with what are believed to be lower counts of stranded dolphins.<ref>{{Cite journal|last1=Jepson|first1=P. D.|last2=Deaville|first2=R.|last3=Acevedo-Whitehouse|first3=K.|last4=Barnett|first4=J.|last5=Brownlow|first5=A.|last6=Brownell Jr|first6=R. L.|last7=Clare|first7=F. C.|last8=Davison|first8=N.|last9=Law|first9=R. J.|last10=Loveridge|first10=J.|last11=MacGregor|first11=S. K.|year=2013|editor1-last=Fahlman|editor1-first=Andreas|title=What Caused the UK's Largest Common Dolphin (Delphinus delphis) Mass Stranding Event?|journal=PLOS ONE|volume=8|issue=4|article-number=e60953|doi=10.1371/journal.pone.0060953|pmc=3640001|pmid=23646103|last17=Seibel|last24=Fernández|last12=Morris|first12=S.|last13=Murphy|first13=S. A.|last14=Penrose|first14=R.|last15=Perkins|last16=Pinn|first16=E.|first24=A.|first23=A. A.|first17=H.|last23=Cunningham|first22=N.|last22=Tregenza|first21=M. L.|last21=Tasker|first20=V.|last20=Simpson|first19=E.|last19=Sierra|first18=U.|last18=Siebert|first15=M. W.|bibcode=2013PLoSO...860953J |doi-access=free}}</ref>

===Conservation===
[[File:Common dolphins (Delphinus delphis) adult and juvenile Sagres.jpg|thumb|Adult and juvenile off Sagres, Portugal]]
[[File:Common Dolphin of genus Delphinus.jpg|thumb|A common dolphin jumping off [[Morro Bay State Marine Recreational Management Area and Morro Bay State Marine Reserve|Morro Bay Nature Reserve]]]]
The common dolphin is probably the most abundant cetacean species on the planet, and the overall species is listed as [[Least-concern species|Least Concern]] on the IUCN Red List,<ref>{{Cite web|last=Hammond|first=P.S.|date=2008|title=''Delphinus delphis'', Short-beaked Common Dolphin|url=https://www.researchgate.net/publication/314246558}}</ref> indicating that it is in no danger of extinction. Abundance has been estimated for most major portions of the species range in the Northern Hemisphere, but only for a few places in the Southern Hemisphere.&nbsp; In the Pacific Ocean, there are an estimated 1,428,000 off Japan and in the temperate central Pacific Ocean,<ref>{{Cite journal|last1=Kanaji|first1=Yu|last2=Yoshida|first2=Hideyoshi|last3=Okazaki|first3=Makoto|date=2017-03-04|title=Spatiotemporal variations in habitat utilization patterns of four Delphinidae species in the western North Pacific, inferred from carbon and nitrogen stable isotope ratios|journal=Marine Biology|language=en|volume=164|issue=4|page=65|doi=10.1007/s00227-017-3107-z|bibcode=2017MarBi.164...65K |s2cid=90520472|issn=1432-1793}}</ref> 969,000 off the U.S. west coast (Carretta et al. 2019); and 2,963,000 in the eastern tropical Pacific.<ref>{{Cite web|url=http://citeseerx.ist.psu.edu/messages/downloadsexceeded.html|access-date=2020-07-22}}</ref> In the Atlantic Ocean, 70,000 are estimated for the western Atlantic Ocean (Waring et al. 2019); 467,000 for European waters;<ref>{{Cite journal|last=Hammond|first=P.S.|date=2017|title=Estimates of cetacean abundance in European Atlantic waters in summer 2016 from the SCANS-III aerial and shipboard surveys|url=https://library.wur.nl/WebQuery/wurpubs/fulltext/414756}}</ref> more than 19,400 for the Mediterranean Sea; and several tens of thousands for the Black Sea.<ref>{{Cite journal|last=Birkun|date=2006|title=Short-beaked common dolphin (''Delphinus delphis ponticus''): Black Sea subspecies.|journal=UCN Centre for Mediterranean Cooperation|pages=16–22}}</ref>&nbsp;In the southern part of the Indo-Pacific Ocean, there are an estimated 20,000-22,000 common dolphins in a small portion of southern Australia (Bilgmann et al. 2017), and 15,000-20,000 off southern Africa.<ref>{{Cite journal|last=Cockcroft|first=Vic|date=1990|title=Seasonal distribution and density of common dolphins Delphinus delphis of the south-east coast of southern Africa|url=https://www.researchgate.net/publication/232906431|journal=South African Journal of Marine Science|volume=9|issue=1 |pages=371–377|doi=10.2989/025776190784378853 |bibcode=1990SAJMS...9..371C }}</ref>&nbsp; There are no estimates for the population of dolphins in the northern Indian Ocean.&nbsp; Taken together, these estimates suggest that well over six million common dolphins inhabit the World's oceans.{{Citation needed|date=August 2025}}

Common dolphins face a mixture of threats due to human influence. Moderate levels of [[Heavy metals|metal pollutants]], which are thought to negatively impact dolphin health,<ref>{{cite journal|author1=Lavery, T. J. |author2=Kemper, C. |author3=Sanderson, K. |author4=Schultz, C. G. |author5=Coyle, P. |author6=Mitchell, J. G. |author7=Seuront, L. |title=Heavy metal toxicity of kidney and bone tissues in South Australian bottlenose dolphins (''Tursiops aduncus'')|doi=10.1016/j.marenvres.2008.09.005|year=2009|journal=Marine Environmental Research|volume=67|pages=1–7|pmid=19012959|issue=1|url=https://hal.archives-ouvertes.fr/hal-00563057/file/PEER_stage2_10.1016%252Fj.marenvres.2008.09.005.pdf }}</ref> have been measured in some populations.<ref>{{cite journal|author1=Lavery, T.J. |author2=Butterfield, N. |author3=Kemper, C.M. |author4=Reid, R.J. |author5=Sanderson, K. |name-list-style=amp |pmid=1800604|year=1991|title=Induction of labor using intracervical prostaglandin E2 gel: The outcome|volume=74|issue=11|pages=491–7|journal=Journal of the Medical Association of Thailand = Chotmaihet Thangphaet}}</ref> Populations have been [[Whaling|hunted]] off the coast of [[Peru]] for use as food and [[shark]] bait. In most other areas, the dolphins have not been hunted directly. Several thousand individuals have been caught in industrial trawler nets throughout their range.

[[Bycatch]] is the main threat that common dolphins face today. Short-beaked common dolphins are taken as cetacean bycatch the most in all of Europe, given that they are the most abundant dolphin in the Eastern Atlantic. About 1000 short-beaked common dolphins are bycaught in the North Atlantic each year by either tuna drift, [[trawling]] and [[gillnetting]]. The regulation is that only cetacean bycatch can not be longer than 15 meters,<ref>{{cite journal|last1=Mannocci|first1=L|last2=Dabin|first2=W|last3=Augeraud-Véron|first3=E|last4=Dupuy|first4=JF|last5=Barbraud|first5=C|last6=Ridoux|first6=V|year=2012|editor1-last=Reina|editor1-first=Richard|title=Assessing the Impact of Bycatch on Dolphin Populations: The Case of the Common Dolphin in the Eastern North Atlantic|journal=PLOS ONE|volume=7|issue=2|article-number=e32615|doi=10.1371/journal.pone.0032615|pmc=3290591|pmid=22393423|bibcode=2012PLoSO...732615M|doi-access=free}}</ref> which exempts short-beaked common dolphins which are only about 2.7 meters. Common dolphin bycatch is a particularly important issue in [[Galicia (Spain)|Galicia]], via [[Fishing trawler|trawler fishing]].<ref name="Fernández-Contreras 1732–1738">{{Cite journal|last1=Fernández-Contreras|first1=M. M.|last2=Cardona|first2=L.|last3=Lockyer|first3=C. H.|last4=Aguilar|first4=A.|date=2010-11-01|title=Incidental bycatch of short-beaked common dolphins (Delphinus delphis) by pairtrawlers off northwestern Spain|url=https://academic.oup.com/icesjms/article/67/8/1732/605256|journal=ICES Journal of Marine Science|language=en|volume=67|issue=8|pages=1732–1738|doi=10.1093/icesjms/fsq077|issn=1095-9289|doi-access=free}}</ref> The bycatch of short beaked dolphins in Galicia from May to September from 2001 to 2002, consisted of 394 individuals annually. Depth was an important factor in bycatch, as incidental capture mostly took place along the continental shelf in water less than {{convert|300|m|abbr=out}} deep. Very few entrapments took place when the depth exceeded 300 m. Time of day was also important as most dolphins became trapped in trawling nets at night (most active feeding takes place at night). Most of the dolphins captured were males and had a mean age of 13+- 4.4 years. It is believed that the reason why the vast majority of bycatch consisted of males is because bachelor pods appear to be particularly abundant in Galicia from the May–October season. This fact reinforces the hypothesis that common dolphins may be sexually segregated in the Northeast Atlantic. If there was a ban on fishing in Galicia in waters than less than 250 m deep, and if there were seasonal closures, it is estimated that 78% of the dolphins would not have been caught.<ref name="Fernández-Contreras 1732–1738" /> In the Western North Atlantic, dolphins are vulnerable to [[driftnet]] fishing targetting [[swordfish]], with the number of males being caught as bycatch, doubling the number of females. It was also found from stranding samples that males tend to strand more. This provides evidence of sex-based habitat partitioning or pod congregation. &nbsp;<ref name="Fernández-Contreras 1732–1738" />

Common dolphins were abundant in the western Mediterranean Sea until the 1960s but occurrences there have tailed off rapidly. The reasons are not well understood, but are believed to be due to extensive human activity in the area. In the US, they are a protected species and sometimes are caught by accident in some trawler nets as by-catch, though despite this they are still quite common throughout their range. Despite these potential threats, the short-beaked common dolphin is considered to be Least Concern by the [[IUCN]] Red List, and the long-beaked common dolphin is listed as Data Deficient.<ref name="iucn status 19 November 2021" />

The short-beaked common dolphin ''Delphinus delphis'' is listed globally on [[Appendix II]]<ref name="Appendices">[https://web.archive.org/web/20110611112003/http://www.cms.int/documents/appendix/Appendices_COP9_E.pdf Appendices I and II of the Convention on the Conservation of Migratory Species of Wild Animals (CMS)]. effective 5 March 2009</ref> of the Convention on the Conservation of Migratory Species of Wild Animals (CMS).<ref>[http://www.cms.int/reports/small_cetaceans/data/d_delphis/d_delphis.htm Convention on Migratory Species page on the Short-beaked common dolphin]. Cms.int. Retrieved on 2014-01-04.</ref> As amended by the Conference of the Parties in 1985, 1988, 1991, 1994, 1997, 1999, 2002, 2005 and 2008. Effective: 5 March 2009 of the [[Convention on Migratory Species|Convention on the Conservation of Migratory Species of Wild Animals]] (CMS) as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements. The Mediterranean population of the short-beaked common dolphin is also listed on Appendix I,<ref name="Appendices" /> as this population has been categorized as being in danger of extinction throughout all or a significant proportion of their range and CMS Parties strive towards strictly protecting these animals, conserving or restoring the places where they live, mitigating obstacles to migration and controlling other factors that might endanger them. In addition, the species is also covered by the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas ([[ASCOBANS]])<ref>[http://www.ascobans.org Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas]. Ascobans.org. Retrieved on 2014-01-04.</ref> and the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area ([[ACCOBAMS]]).<ref>[http://www.accobams.org Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area]. Accobams.org. Retrieved on 2014-01-04.</ref>

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

==References==
{{Reflist}}

==Further reading==
*Rice, Dale W. (1998). Marine mammals of the world: systematics and distribution. Society of Marine Mammalogy Special Publication Number 4. 231 pp.
*''Encyclopedia of Marine Mammals'' {{ISBN|0-12-551340-2}}
*''Whales, Dolphins and Porpoises'', Mark Carwardine, {{ISBN|0-7513-2781-6}}
* Heptner, V. G.; Nasimovich, A. A; Bannikov, Andrei Grigorevich; Hoffmann, Robert S, ''[https://archive.org/details/mammalsofsov231996gept Mammals of the Soviet Union]'', Volume II, part 3 (1996). Washington, D.C. : Smithsonian Institution Libraries and National Science Foundation

==External links==
{{Commons}}
*[https://www.wdcs.org: Whale and Dolphin Conservation Society] {{Webarchive|url=https://web.archive.org/web/20210613183112/https://www.wdcs.org/ |date=2021-06-13 }}

{{Cetacea|O.}}
{{Odontoceti|D.}}
{{Taxonbar|from=Q312257}}

[[Category:Oceanic dolphins]]
[[Category:Mammals described in 1758]]
[[Category:Cetaceans of Europe]]
[[Category:Cetaceans of the Indian Ocean]]
[[Category:Cetaceans of the Pacific Ocean]]
[[Category:Mammals of Southeast Asia]]
[[Category:Animal taxa named by Carl Linnaeus]]