Whale shark: Difference between revisions

| fossil_range = {{Geological range|28.4|0|ref=<ref name=FW>{{cite web | title = ''Rhincodon typus'' in the Paleobiology Database | work = [[Fossilworks]] | url = https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=170186 | access-date = 17 December 2021 | archive-date = 27 May 2022 | archive-url = https://web.archive.org/web/20220527183518/http://www.fossilworks.org/cgi-bin/bridge.pl?a=taxonInfo&taxon_no=170186 | accessurl-datestatus = 17live December 2021}}</ref>}}

Whale sharks possess a broad, flattened head with a large mouth and two small eyes located at the front corners.<ref name=":2">{{Cite journal |last=Colman |first=J. G. |date=1997 |title=A review of the biology and ecology of the whale shark |journal=Journal of Fish Biology |language=en |volume=51 |issue=6 |pages=1219–1234 |bibcode=1997JFBio..51.1219C |doi=10.1111/j.1095-8649.1997.tb01138.x |issn=1095-8649 |pmid=29991171}}</ref><ref name=":9" /> Unlike many other sharks, whale shark mouths are located at the front of the head rather than on the underside of the head.<ref>{{Cite web|url=http://marinebio.org/species.asp?id=47|title=Whale Sharks, Rhincodon typus |website=MarineBio.org|access-date=17 May 2018}}</ref> A {{convert|12.1|m|ft|1|abbr=on}} whale shark was reported to have a mouth {{convert|1.55|m|ft|1|abbr=on}} across.<ref>{{Cite journal |last1=Kaikini |first1=A. S. |last2=Ramamohana Rao |first2=V. |last3=Dhulkhed |first3=M. H. |date=1959 |title=A note on the whale shark Rhincodon typus Smith, stranded off Mangalore |url=https://core.ac.uk/display/33012000 |journal=Central Marine Fisheries Research Unit, Mangalore.}}</ref> Whale shark mouths can contain over 300 rows of tiny teeth and 20 filter pads which it uses to [[filter feeder|filter feed]].<ref name="FAO">{{cite web |last=Compagno |first=L. J. V. |title=Species Fact Sheet, ''Rhincodon typus'' |url=http://www.fao.org/fishery/species/2801/en |access-date=19 September 2006 |publisher=Food and Agriculture Organization of the United Nations}}</ref> The [[Spiracle (vertebrates)|spiracle]]s are located just behind the eyes. Whale sharks have five large pairs of [[gill]]s. Their skin is dark grey with a white belly marked with an arrangement of pale grey or white spots and stripes that is unique to each individual. The skin can be up to {{convert|15|cm|in|1|abbr=on}} thick and is very hard and rough to the touch. The whale shark has three prominent ridges along its sides, which start above and behind the head and end at the [[caudal peduncle]].<ref name=":9">{{Cite book|author=Norman, Brad |title=CITES identification manual|date=2002|publisher=Environment Australia|isbn=0-642-54900-1 |oclc=54364165}}</ref> The shark has two [[dorsal fin]]s set relatively far back on the body, a pair of [[pectoral fins]], a pair of pelvic fins and a single medial [[anal fin]]. The [[caudal fin]] has a larger upper lobe than the lower lobe ([[wiktionary:heterocercal|heterocercal]]).

[[Rhodopsin]], the light-sensing pigment in the [[rod cell]]s of the retina, is normally sensitive to green and used to see in dim light, but in the whale shark (and the bottom-dwelling [[cloudy catshark]]) two amino acid substitutions make the pigment more sensitive to blue light instead, the light that dominates the deep ocean. One of these mutations also makes rhodopsin vulnerable to higher temperatures. In humans, a similar mutation leads to [[congenital stationary night blindness]], as the human body temperature makes the pigment decay.<ref>{{Cite web|url=https://www.sciencedaily.com/releases/2023/03/230329091933.htm|title=How whale shark rhodopsin evolved to see, in the deep blue sea|website=ScienceDaily}}</ref><ref>{{Cite web|url=https://www.japantimes.co.jp/news/2023/04/09/national/science-health/whale-sharks-mutation-blindness-humans/|title=Whale sharks see in dark due to mutation behind blindness in humans|date=9 April 2023|website=The Japan Times}}</ref> This pigment becomes unstable in shallow water, where the temperature is higher and the full spectrum of light is present. To protect from this instability, the whale shark deactivates the pigment when in shallow water (as otherwise the pigment would hinder full color vision). In the colder environment at 2,000 meters below the surface where the shark dives, it is activated again.<ref>{{Cite web|url=https://www.sciencetimes.com/articles/43109/20230403/whale-sharks-see-dark-due-genetic-mutation-light-sensing-pigment.htm|title=Whale Sharks Can See in the Dark Due to Genetic Mutation; Light-Sensing Pigment in Retina Works in Dim Environment|first=Caleb|last=White|date=3 &#124;April 2023|website=Science Times}}</ref> The mutations thus allow the shark to see well at both ends of its great vertical range.<ref>{{Cite journal |last1=Yamaguchi |first1=Kazuaki |last2=Koyanagi |first2=Mitsumasa |last3=Sato |first3=Keiichi |last4=Terakita |first4=Akihisa |last5=Kuraku |first5=Shigehiro |date=2023-03-28 |title=Whale shark rhodopsin adapted to deep-sea lifestyle by a substitution associated with human disease |journal=Proceedings of the National Academy of Sciences |language=en |volume=120 |issue=13 |pages=e2220728120 |doi=10.1073/pnas.2220728120 |pmid=36943890 |issn=0027-8424|pmc=10068813 |bibcode=2023PNAS..12020728Y }}</ref><ref>{{Cite web |title=Mutation behind night blindness in humans helps whale sharks see in the dark |url=https://www.science.org/content/article/mutation-behind-night-blindness-humans-helps-whale-sharks-see-dark |access-date=2023-03-26 |website=www.science.org |language=en}}</ref> The eyes have also lost all [[cone cell|cone]] [[opsin]]s except LWS.<ref>{{Cite journal|url=https://www.biorxiv.org/content/10.1101/2021.10.01.462724v1|title=Whale shark rhodopsin adapted to its vertically wide-ranging lifestyle|first1=Kazuaki|last1=Yamaguchi|first2=Mitsumasa|last2=Koyanagi|first3=Keiichi|last3=Sato|first4=Akihisa|last4=Terakita|first5=Shigehiro|last5=Kuraku|date=1 October 2021|pages=2021.10.01.462724|via=bioRxiv|doi=10.1101/2021.10.01.462724|s2cid=238261190 }}</ref>

Scott A. Eckert & Brent S. Stewart reported on [[Animal migration tracking|satellite tracking]] of whale sharks from between 1994 andto 1996. Out of the 15 individuals tracked, two females were reported as measuring {{convert|15|m|ft|abbr=on}} and {{convert|18|m|ft|abbr=on}} respectively.<ref>{{Cite journal|last1=Eckert|first1=Scott A.|last2=Stewart|first2=Brent S.|s2cid=22173382|date=2001-02-01|title=Telemetry and Satellite Tracking of Whale Sharks, Rhincodon Typus, in the Sea of Cortez, Mexico, and the North Pacific Ocean|journal=Environmental Biology of Fishes|language=en|volume=60|issue=1|pages=299–308|doi=10.1023/A:1007674716437|bibcode=2001EnvBF..60..299E |issn=1573-5133}}</ref> A {{convert|20.75|m|ft|abbr=on}} long whale shark was reported as being stranded along the [[Ratnagiri]] coast in 1995.<ref>{{Cite journal|last=Katkar |first=B.N.|date=1996|title=Turtles and whale shark landed along ratnagiri coast, maharashtra |url=https://core.ac.uk/reader/33018228|journal=Marine Fisheries Information Service|volume=141 |pages=20}}</ref><ref name=":3">{{Cite journal|last1=Venkatesan|first1=V|last2=Ramamurthy|first2=N|last3=Boominathan |first3=N|last4=Gandhi|first4=A|date=2008|title=Stranding of a whale shark, Rhincodon typus (smith) at Pamban, Gulf of Mannar|url=https://core.ac.uk/download/pdf/33014069.pdf|journal=Marine Fisheries Information Service|volume=198 |pages=19–22}}</ref> A female individual with a [[Fish measurement|standard length]] of {{convert|15|m|ft|1|abbr=on}} and an estimated total length at {{convert|18.8|m|ft|1|abbr=on}} was reported from the Arabian Sea in 2001.<ref>{{Cite journal |last1=Borrell|first1=Asunción|last2=Aguilar|first2=Alex|last3=Gazo|first3=Manel|last4=Kumarran|first4=R. P. |last5=Cardona|first5=Luis|s2cid=37683420|date=2011|title=Stable isotope profiles in whale shark (Rhincodon typus) suggest segregation and dissimilarities in the diet depending on sex and size|journal=Environmental Biology of Fishes|volume=92|issue=4|pages=559–567|doi=10.1007/s10641-011-9879-y |bibcode=2011EnvBF..92..559B |issn=0378-1909}}</ref> In a 2015 study looking intoreviewing the size of marine [[megafauna]], McClain and colleagues considered this female as being the most reliable and accurately measured.<ref name=":1" />

Growth, longevity, and reproduction of the whale shark are poorly understood.<ref name=":5" /><ref name=":6" /><ref name="ong">{{cite journal|last1=Ong|first1=Joyce J. L.|last2=Meekan|first2=Mark G.|last3=Hsu|first3=Hua Hsun|last4=Fanning|first4=L. Paul|last5=Campana|first5=Steven E.|date=6 April 2020|title=Annual Bands in Vertebrae Validated by Bomb Radiocarbon Assays Provide Estimates of Age and Growth of Whale Sharks|journal=Frontiers in Marine Science|volume=7|doi=10.3389/fmars.2020.00188|doi-access=free|hdl=20.500.11815/2381|hdl-access=free}}</ref> There

[[Age wasdetermination uncertaintyin as to whether vertebraefish|Vertebral growth bands]] arehave formedbeen annuallyused or biannually, which is important into determiningestimate the age, growth, and longevity of whale sharks. However, there was uncertainty as to whether vertebrae growth bands are formed annually or biannually.<ref name=":8">{{Cite journal|last=Wintner|first=Sabine P.|s2cid=20461057|date=2000|title=Preliminary Study of Vertebral Growth Rings in the Whale Shark, Rhincodon typus, from the East Coast of South Africa|journal=Environmental Biology of Fishes|volume=59|issue=4|pages=441–451|doi=10.1023/A:1026564707027|bibcode=2000EnvBF..59..441W }}</ref><ref name=":4" /><ref name=":5" /> A 2020 study compared the ratio of [[Carbon-14]] isotopes found in growth bands of whale shark vertebrae to [[Nuclear weapons testing|nuclear testing]] events in the 1950-60s1950–60s, finding that growth bands are laid down annually. The study found an age of 50 years for a {{convert|10|m|ft|abbr=on}} female and 35 years for a {{convert|9.9m9|m|ft|abbr=on}} male.<ref name="ong" /> Various studies looking at vertebrae growth bands and measuring whale sharks in the wild have estimated their lifespans from ~80 years and up to ~130 years.<ref name=":4" /><ref name="fishbase" /><ref name=":5" />

In a report from [[Rappler]] last August 2019, whale sharks were sighted during [[World Wide Fund for Nature|WWF]] [[Philippines]]' photo identification activities in the first half of the year. There were a total 168 sightings – 64 of them “re"re-sightings”sightings" or reappearances of previously recorded whale sharks. WWF noted that “very"very young whale shark juveniles" were identified among the 168 individuals spotted in the first half of 2019. Their presence suggests that the [[Ticao Pass]] may be a pupping ground for whale sharks, further increasing the ecological significance of the area.<ref>{{cite news |title='Largest number in years': Over 100 new whale sharks spotted in Donsol |url=https://www.rappler.com/science-nature/environment/238898-increase-sighting-whale-sharks-donsol-sorsogon |access-date=4 March 2020 |publisher=Rappler.com |date=August 30, 2019}}</ref>

Despite its size, the whale shark does not pose any danger to humans. Younger whale sharks are gentle and can play with divers. Underwater photographers such as [[Fiona Ayerst]] have photographed them swimming close to humans without any danger.<ref name="content.time.com">[httphttps://content.time.com/time/today-in-pictures/0,31511,1914578,00.html Pictures of the Day: Tuesday, Aug. 04, 2009]. ''Time magazine'', "A 40-foot whale shark and a brave snorkeler swim off the South African coast."</ref> Although whale sharks are docile fish, touching or riding the sharks is strictly forbidden and fineable in most countries,<ref>{{Cite web |last=Russell |first=Mark 'Crowley' |date=2024-04-09 |title=Scuba diver fined for pulling whale shark tail in Thailand |url=https://divemagazine.com/scuba-diving-news/scuba-diver-fined-pulling-thailand-whale-shark-tail |access-date=2024-07-11 |website=DIVE Magazine |language=en-GB}}</ref><ref>{{Cite web |title=Whale Sharks ⋅ Saint Helena Island Info ⋅ About St Helena, in the South Atlantic Ocean |url=http://sainthelenaisland.info/whalesharks.htm |access-date=2024-07-11 |website=sainthelenaisland.info}}</ref><ref>{{Cite web |title=Government of Western Australia, Department of Fisheries. Whale Shark |url=https://www.fish.wa.gov.au/documents/recreational_fishing/fact_sheets/fact_sheet_whale_shark.pdf|title=Government of Western Australia, Department of Fisheries. Whale Shark}}</ref>, as it can cause serious harm to the animal.<ref>Whitehead, Darren Andrew (2014) [http://uhra.herts.ac.uk/bitstream/handle/2299/14655/14094628-%20Whitehead%20Darren%20-%20Final%20MSc%20by%20Research%20submission.pdf?sequence=1 Establishing a quantifiable model of whale shark avoidance behaviours to anthropogenic impacts in tourism encounters to inform management actions], University of Hertfordshire.</ref><ref>{{Cite web |last=Reporter |first=Jess Thomson Science |date=2022-11-30 |title=Man filmed riding world's biggest shark in tourism stunt |url=https://www.newsweek.com/whale-shark-touched-video-dangerous-outrage-1763473 |access-date=2024-07-11 |website=Newsweek |language=en}}</ref><ref>{{Cite web |title=Friend of the Sea Sustainable Whale Shark Watching Standard |url=https://friendofthesea.org/wp-content/uploads/Sustainable-Whale-Shark-Watching-Standard_01042020-1.pdf|title=Friend of the Sea Sustainable Whale Shark Watching Standard}}</ref>

HundredsIt was reported in 2014 that hundreds of whale sharks arewere illegally killed every year in China for their fins, skins, and oil.<ref>{{cite news | url=http://www.abc.net.au/news/2014-02-05/an-hundreds-of-sharks-killed-annually-in-illegal-trade-in-china/5239568 | title=Hundreds of sharks killed in China| newspaper=ABC News| date=5 February 2014| last1=Hilton/Greenpeace| first1=Paul}}</ref>

Outside Asia, the first and so far only place to keep whale sharks is [[Georgia Aquarium]] in [[Atlanta]], United States.<ref name=Mollet2012/> This is unusual because of the comparatively long transport time and complex logistics required to bring the sharks to the aquarium, ranging between 28 and 36 hours.<ref name=Schreiber2017/> Georgia keeps two whale sharks: two males, Taroko and Yushan, who both arrived in 2007.<ref>{{cite news |date=1 June 2007 |title=Aquarium gains two new whale sharks |publisher=CNN |url=http://www.cnn.com/2007/TECH/science/06/01/aquarium.whale.sharks.ap/index.html |access-date=1 June 2007 |url-status=dead |archive-url=https://web.archive.org/web/20070603085148/http://www.cnn.com/2007/TECH/science/06/01/aquarium.whale.sharks.ap/index.html |archive-date=3 June 2007}}</ref> Two earlier males at Georgia Aquarium, Ralph and Norton, both died in 2007.<ref name=Moore2011/> Trixie died in 2020. Alice died in 2021. Georgia's whale sharks were all imported from Taiwan and were taken from the commercial fishing quota for the species, usually used locally for food.<ref name=Schreiber2017/><ref name=Sundquist2013>{{cite news | author=Sundquist, T. | title=Transporting the World's Largest Fish: A Whale [Shark] of a Task | url=https://www.promegaconnections.com/transporting-the-worlds-largest-fish-a-whale-shark-of-a-task/ | publisher=Promega Connections | date=18 September 2013 | access-date=8 November 2017 | archive-date=8 March 2021 | archive-url=https://web.archive.org/web/20210308124851/https://www.promegaconnections.com/transporting-the-worlds-largest-fish-a-whale-shark-of-a-task/ | url-status=dead }}</ref> Taiwan closed this fishery entirely in 2008.<ref name=Sundquist2013/>

In the Philippines, it is called {{lang|fil|butanding}} and {{lang|fil|balilan}}.<ref>[http://www.oneocean.org/ambassadors/sharks/index.html Ocean Ambassadors – Sharks]. Oneocean.org. Retrieved 23 May 2013.</ref> The whale shark is featured on the reverse of the [[Philippine one hundred-peso note|Philippine 100-peso bill]]. By law snorkelers must maintain a distance of {{cvt|4|ft}} from the sharks and there is a fine and possible prison sentence for anyone who touches the animals.<ref>{{cite web |last=Cannon |first=Marisa |date=21 July 2015 |title=Swimming with whale sharks in the Philippines |website=cnn.com |publisher=CNN |url=http://edition.cnn.com/2015/07/05/travel/whale-shark-oslob/index.html |access-date=16 August 2015}}</ref>