Editing Dolphin (section)

===Locomotion===
Dolphins have two pectoral flippers, each containing four digits, a boneless [[dorsal fin]] for stability, and a fluke for propulsion. Although dolphins do not possess external hind limbs, some possess discrete rudimentary appendages, which may contain feet and digits. Orcas are fast swimmers in comparison to seals which typically cruise at {{convert|9|–|28|km/h|mph|abbr=on}}; the orca, in comparison, can travel at speeds up to {{convert|55.5|km/h|mph|abbr=on}}.{{Citation needed|date=February 2024}} A study of a Pacific white-sided dolphin in an aquarium found fast burst acceleration, with the individual being able with 5 strokes (2.5 fluke beats) to go from 5.0 m s-1 to 8.7 m s-1 in 0.7 seconds.<ref name="Tanaka Li Uchida Nakamura 2019 p. e0210860">{{cite journal |last1=Tanaka |first1=Hiroto |last2=Li |first2=Gen |last3=Uchida |first3=Yusuke |last4=Nakamura |first4=Masashi |last5=Ikeda |first5=Teruaki |last6=Liu |first6=Hao |date=2019 |title=Measurement of time-varying kinematics of a dolphin in burst accelerating swimming |journal=PLOS ONE |volume=14 |issue=1 |page=e0210860 |doi=10.1371/journal.pone.0210860 |issn=1932-6203 |pmc=6353170 |pmid=30699184 |doi-access=free|bibcode=2019PLoSO..1410860T }}</ref>

The fusing of the neck vertebrae, while increasing stability when swimming at high speeds, decreases flexibility, which means most dolphins are unable to turn their heads.<ref>{{cite web|url=http://yellowmagpie.com/beluga-whale/ |title=Beluga Whale: The White Melon-headed Creature Of The Cold |publisher=Yellowmagpie.com |date=June 27, 2012 |access-date=August 12, 2013}}</ref><ref>{{cite web |url=http://www.whalesalive.org.au/aboutwhales.html |title=About Whales |publisher=Whalesalive.org.au |date=June 26, 2009 |access-date=August 12, 2013 |archive-url=https://web.archive.org/web/20130812000655/http://whalesalive.org.au/aboutwhales.html |archive-date=August 12, 2013 |url-status=dead }}</ref> [[River dolphin]]s have non-fused neck vertebrae and can turn their heads up to 90°.<ref>{{cite journal|url=http://acsonline.org/fact-sheets/boto-amazon-river-dolphin/|title=Boto (Amazon river dolphin) ''Inia geoffrensis''|journal=American Cetacean Society|year=2002|access-date=September 12, 2015}}</ref> Dolphins swim by moving their fluke and rear body vertically, while their flippers are mainly used for steering. Some species [[Cetacean surfacing behaviour#Porpoising|porpoise]] out of the water, which allows them to travel faster. Their skeletal anatomy allows them to be fast swimmers. All species have a [[dorsal fin]] to prevent themselves from involuntarily spinning in the water.<ref name="Cetacean anatomy" /><ref name="Dolphins">{{cite book |author1=Klinowska, Margaret |author2=Cooke, Justin |year=1991 |title=Dolphins, Porpoises, and Whales of the World: the IUCN Red Data Book |url=https://portals.iucn.org/library/sites/library/files/documents/RD-1991-001.pdf |access-date=August 29, 2015}}</ref>

Some dolphins are adapted for diving to great depths. In addition to their streamlined bodies, some can selectively slow their [[heart rate]] to conserve oxygen.<ref name="phys-dolphins">{{cite news |title=Dolphins conserve oxygen and prevent dive-related problems by consciously decreasing their heart rates before diving |url=https://phys.org/news/2020-11-dolphins-oxygen-dive-related-problems-consciously.html |access-date=8 December 2020 |work=phys.org |language=en}}</ref><ref>{{cite journal |last1=Fahlman |first1=Andreas |last2=Cozzi |first2=Bruno |last3=Manley |first3=Mercy |last4=Jabas |first4=Sandra |last5=Malik |first5=Marek |last6=Blawas |first6=Ashley |last7=Janik |first7=Vincent M. |title=Conditioned Variation in Heart Rate During Static Breath-Holds in the Bottlenose Dolphin (Tursiops truncatus) |journal=[[Frontiers in Physiology]] |date=2020 |volume=11 |page=604018 |doi=10.3389/fphys.2020.604018 |pmid=33329056 |pmc=7732665 |s2cid=227128277 |language=en |issn=1664-042X|doi-access=free }} [[File:CC-BY icon.svg|50px]] Available under [https://creativecommons.org/licenses/by/4.0/ CC BY 4.0].</ref> Some can also re-route blood from tissue tolerant of water pressure to the heart, brain and other organs. Their [[hemoglobin]] and [[myoglobin]] store oxygen in body tissues, and they have twice as much myoglobin as hemoglobin.<ref>{{cite journal |author1=Norena, S. R. |author2=Williams, T. M. |title=Body size and skeletal muscle myoglobin of cetaceans: adaptations for maximizing dive duration |journal= Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology|volume=126 |issue=2 |year=2000 |pages=181–191|doi=10.1016/s1095-6433(00)00182-3 |pmid=10936758}}</ref>