View source for Orange clownfish

{{Short description|Species of fish}}
{{Speciesbox 
| image = A._percula.jpg
| status = LC
| status_system = IUCN3.1
| status_ref = <ref name="iucn status 19 November 2021">{{cite iucn |author=Jenkins, A. |author2=Allen, G. |author3=Myers, R. |author4=Yeeting, B. |author5=Carpenter, K.E. |date=2017 |title=''Amphiprion percula'' |volume=2017 |article-number=e.T188372A1865631 |doi=10.2305/IUCN.UK.2017-2.RLTS.T188372A1865631.en |access-date=19 November 2021}}</ref>
| taxon = Amphiprion percula
| authority = ([[Bernard Germain Étienne de la Ville, Comte de Lacépède|Lacepède]], 1802)
| synonyms = *''Lutjanus percula'' <small>Lacepède, 1802</small> 
*''Actinicola percula'' <small>(Lacepède, 1802)</small> 
*''Amphiprion tunicatus'' [[Georges Cuvier|Cuvier]], 1830 
}}
The '''orange clownfish''' (''Amphiprion percula'') also known as '''percula clownfish''' and '''clown anemonefish''', is widely known as a popular [[aquarium]] fish. Like other [[clownfish]]es (also known as anemonefishes), it often lives in association with [[sea anemone]]s. ''A. percula'' is associated specifically with ''[[Heteractis magnifica]]'' and ''[[Stichodactyla gigantea]]'', and as larvae use chemical cues released from the anemones to identify and locate the appropriate host species to use them for shelter and protection.<ref name=Elliot95>{{cite journal |doi=10.1007/BF00350870 |vauthors=Elliot JK, Elliot JM, Mariscal RN |title=Host selection, location, and association behaviors of anemonefishes in field settlement experiments |journal=Marine Biology |volume=122 |pages=377–389 |year=1995 |issue=3|bibcode=1995MarBi.122..377E |s2cid=83934512 }}</ref> This causes preferential selection when finding their anemone host species.<ref name=Lee03>Lee, J. 2003. "''Amphiprion percula''"(Online).</ref> Although popular, maintaining this species in captivity is rather complex. The [[Great Barrier Reef Marine Park Authority]] regulates the number of collection permits issued to aquarium fish dealers who seek this, and other tropical fish within the [[Great Barrier Reef Marine Park]].
The [[symbiosis]] between anemonefish and anemones depends on the presence of the fish drawing other fish to the anemone, where they are stung by its venomous [[tentacle]]s. The anemone helps the fish by giving it protection from predators, which include [[brittle star]]s, [[wrasse]]s, and other [[damselfish]], and the fish helps the anemone by feeding it, increasing oxygenation, and removing waste material from the host. Various hypotheses exist about the fish's ability to live within the anemone without being harmed. One study carried out at Marineland of the Pacific by Dr. Demorest Davenport and Dr. Kenneth Noris in 1958 revealed that the mucus secreted by the anemone fish prevented the anemone from discharging its lethal stinging [[nematocyst]]s. A second hypothesis is that ''A. percula'' has acquired immunity towards the sea anemone's toxins, and  a combination of the two has been shown to be the case.<ref>{{cite journal |doi=10.1016/0041-0101(94)90390-5 |author=Mebs D |title=Anemonefish Symbiosis: Vulnerability and Resistance of Fish to the Toxin of the Sea Anemone |journal=Toxicon |volume=32 |issue=9 |pages=1059–1068 |year=1994 |pmid=7801342|bibcode=1994Txcn...32.1059M }}</ref> The fish feed on [[algae]], [[zooplankton]], [[worm]]s, and small [[crustacean]]s.

==Description==
''Amphiprion percula'' can grow to be {{convert|11|cm|abbr=on}} in length, but is on average {{convert|8|cm|abbr=on}}, and can be recognized by three white lines across their bright orange bodies, with no distinction in color between sexes. The anterior white bar is placed just behind the eye, the middle bar goes straight down the middle of the fish, and the posterior bar occurs near the [[caudal fin]]. An anterior projecting bulge also exists on the middle bar. In addition to the white coloring, black edging outlines each fin with varying thickness.<ref name=Lee03/> This species can be mistaken for the similar species of clownfishes, ''A. ocellaris''. This is known as the [[ocellaris clownfish]] and sometimes referred to as the "false percula clownfish" or "common clownfish" due to its similar color and pattern. The "easiest" way to distinguish the two species is the fact that ''A. percula'' has 10 spines in the first [[dorsal fin]] (rarely having 9) and ''A. ocellaris'' has 11 (rarely 10), which is a more reliable distinction than color patterns. ''A. ocellaris'' does not have thick black edging outlining the fins.<ref name=Lee03/>

[[Marine heatwave]]s are known for negatively effecting the growth patterns of species of [[vertebrate]]s. To combat the [[Hyperthermia|heat stress]], Orange clownfish are able to shrink their bodies. The amount they shrink is modulated by their social rank and size with individuals that shrink more often than others with their breeding partner have a higher chance of survival during [[Heat wave|heatwaves.]]<ref>{{Cite journal |last=Versteeg |first=Melissa A. |last2=MacDonald |first2=Chancey |last3=Bennett-Smith |first3=Morgan F. |last4=Buston |first4=Peter M. |last5=Rueger |first5=Theresa |date=2025-05-21 |title=Individual clown anemonefish shrink to survive heat stress and social conflict |url=https://www.science.org/doi/10.1126/sciadv.adt7079 |journal=Science Advances |volume=11 |issue=21 |article-number=eadt7079 |doi=10.1126/sciadv.adt7079 |pmc=12094202 |pmid=40397728}}</ref>

==Reproduction==
Since these fish live in a warm-water environment, they can reproduce all year long. Each group of fish consists of a [[breeding pair]] and none to four nonbreeders. Within each group there is a size-based hierarchy: the female is largest, the breeding male is second largest, and the male non-breeders get progressively smaller as the hierarchy descends.<ref name=Buston04>{{cite journal |author=Buston PM |title=Territory inheritance in clownfish |journal=Proc. Biol. Sci. |volume=271 |issue=Suppl 4 |pages=S252–4 |date=May 2004 |pmid=15252999 |pmc=1810038 |doi=10.1098/rsbl.2003.0156 }}</ref> They exhibit [[protandry]], meaning each fish is born male, but changes to female if the sole breeding female dies. If the female dies, the breeding male becomes the breeding female, and the largest nonbreeder becomes the breeding male. The spawning process is correlated with the lunar cycle. At night time the moon maintains a higher level of alertness in ''A. percula'' and this increases the interaction with the males and females. Before spawning, the male attracts the female via courting behaviour. These courting actions include extending their fins, biting the female and chasing her. The males also swim rapidly in an upward and downward motion to attract the females. The nest site is also important for the survival of the eggs.<ref name=Lee03/> Depending on her size, the female spawns about 400–1500 eggs per cycle.<ref>{{cite journal |author=Alava, Veronica R., Gomes, Luiz. |title=Breeding Marine Aquarium Animals: The Anemonefish. Naga |journal=The ICLARM Quarterly |pages=12–13 |date=July 1989 }}</ref> The expected tenure of breeding females is roughly 12 years and is relatively long for a fish of its size, but is characteristic of other [[reef]] fish.<ref>{{cite journal |doi=10.1007/s00265-004-0833-2 |author=Buston P |title=Does the presence of non-breeders enhance the fitness of breeders? An experimental analysis in the clown anemonefish ''Amphiprion percula'' |journal=Behavioral Ecology and Sociobiology |volume=57 |pages=23–31 |year=2004|issue=1 |bibcode=2004BEcoS..57...23B |s2cid=24516887 }}</ref>

Why the nonbreeders continue to associate with these groups has been unclear.  Unlike nonreproductives in some animal groups, they cannot obtain occasional breeding opportunities, because their [[gonad]]s are not functional.  They cannot be regarded as [[helpers at the nest]], since their presence does not increase the reproductive success of the breeders.  Recent research<ref>(Buston, 2004)</ref> suggests that they are simply queuing for the [[territory (animal)|territory]] occupied by the breeders, i.e. the anemone; nonbreeders living in association with breeders have a better chance of eventually securing a territory than a nonresident.<ref name=Buston04/> The probability of a fish ascending in rank in this queue is equal to that of the individual outliving at least one of its dominants because an individual ascends in rank if any one of its dominants dies, and not simply when its immediate dominant dies.<ref name=Buston04/>

The development of the fish from juvenile to adult is dependent on the system of hierarchy, and can be described as density-dependent. Aggression is involved in these small families, although usually not between the male and the female. The aggression usually exists between the males. The largest male suppresses the development of the next smallest male, and the cycle continues until the smallest fish is evicted from the host anemone. Within each anemone, the regulation of the species is controlled by the female, since the amount of space for fish in her anemone is directly proportional to her size (which eventually reaches a maximum), so she ultimately controls the size of the other fish.<ref>{{cite journal |author=Fautin, Daphne G. |title=Anemonefish Recruitment: The Roles of Order and Chance |journal=Symbiosis |volume=14 |pages=143–160 |year=1992}}</ref> ''A. percula'' is a very competitive fish and this causes the smaller fish to have stunted growth. A potential exists for a fish to ascend in rank by contesting its dominant. This depends on the relative body sizes of the two fish, and is very unlikely to happen since ''A. percula'' maintains well-defined size differences between individuals adjacent in rank.<ref name=Buston04/> However, in an [[aquarium]], this fish is peaceful, and it can live in an aquarium environment well.

The fish lay their eggs in a safe spot close to the anemone from where they are easily protected, and the parents can retreat to safety if danger threatens. Anemonefish usually lay their nests in the evening after a few days of carefully cleaning and examining the chosen site.  Preferred egg sites are flat or slightly curved rocks or some other item the fish have dragged near their nest for the purpose.  (In captivity, clay pots and saucers are an attractive choice.) First, the female deposits some eggs with her [[ovipositor]] (a whitish tube descending from her belly), making a wiggling pass over the surface, then the male follows behind her, fertilizing the eggs.  After many passes, the nest is complete and will hatch in 6–8 days shortly after sunset, usually on a very dark night.  In the meantime, the male is very protective of the nest and ceaselessly fans the eggs to provide proper oxygen circulation, and checks them for any bad eggs, which he eats before they can rot and damage more eggs. Females may help the male tend the nest.  At hatching, the larvae burst free and swim up toward the moonlight and the open ocean to ride the currents and eat [[plankton]] for about a week, before the still tiny metamorphosed clowns return to the reef and look for an anemone in which to settle. Eventually, the cycle repeats.

==Recruitment==
Recruitment is the number of individuals in a given species that can survive within a certain amount of time following larval habitation.<ref name=Elliot01>{{cite journal |doi=10.1007/s002270000441 |vauthors=Elliott JK, Mariscal RN |title=Coexistance of nine anemonefish species: differential host and habitat utilization, size and recruitment |journal=Marine Biology |volume=138 |pages=23–36 |year=2001|issue=1 |bibcode=2001MarBi.138...23E |s2cid=84330335 }}</ref> The higher the level of recruitment, the better chance a larva has of surviving long enough to become an adult fish. Large food supplies, low predator threats, and the availability of nearby anemones are all factors that affect their recruitment levels. 
''A. percula'', like most coral reef fish, has a bipartite lifecycle, which has a scattering pelagic larval stage, whereas its resident phase is motionless. At the end of the pelagic phase, the [[larva]]e begin to settle on the coral reef and begin their recruiting process in the resident population.<ref name=Buston04/> Larvae that settle successfully and join a resident population are called recruits. Anemonefish species are recruited to areas where the fish are commonly found. Most anemonefish are site-attached and do not move from one anemone to another that are spatially distributed more than a few meters. This is simply because it is always a dangerous undertaking for ''A. percula'' to be outside its anemonefish safe haven, exposed to dangerous predators. They are also very poor swimmers, increasing the risk involved in travel.<ref name=Buston04/>
Recruitment is essentially the only method that the fish can use to inhabit new anemones. Finding a better living situation in a different anemone is unlikely because every anemone is already occupied by other anemonefish species. Anemonefish are known for reproducing all year round when they are in lower latitudes and recruitment with these fish is anticipated to follow the same pattern.<ref name=Elliot01/>

==Habitat==
[[File:Seattle Aquarium 20161219 Clownfish 01.jpg|alt=Clownfish with Pacific Coral Reef anemones|thumb|Clownfish with Pacific coral reef anemones at the Seattle Aquarium]]
Anemonefish are specialized coral reef fish that live within host anemones and are found in warmer waters in the Pacific and Indian Oceans, off northwest Australia, southeast Asia, and Japan.
Both ''A. percula'' and the anemones reside in shallow waters and the depth usually does not exceed 12 m with water temperatures ranging between 25 and 28&nbsp;°C.<ref name=Lee03/> Host [[Sea anemone|anemone]]s, which are tube-like organisms that reside on coral reefs, are usually occupied by only one anemonefish species because one species outcompetes and exclude other species when they inhabit the same host anemone. Unless a significant size difference exists, two anemonefish species  show aggression towards each other when trying to occupy the same host anemone.<ref name=Elliot01/> This is why the supply of nearby anemone hosts so strongly influences ''A. percula''<nowiki />'s ability to achieve recruitment and survival in general.
A primary host anemone has an anemonefish at a high frequency and a secondary host anemone has one at a relatively low frequency. The distribution and availability of sea anemones is limited by the activity of [[photosynthesis]] of algae that occupy the anemones' tentacles.<ref name=Lee03/> Secondary hosts are usually only used if a severe lack of available primary hosts exists. When many different species of anemonefishes occupy similar habitats, they tend to spread themselves out according to smaller microhabitats and available species of anemones. ''A. percula'' and ''A. perideraion'' both essentially live within the ''H. magnifica'' anemone, but ''A. percula'' has the highest selection ratios with the ''S. gigantea''.<ref name=Elliot01/> A study done by Elliot & Mariscal in the region of Madang, Papua New Guinea found that all of the ''H. magnifica'' anemones that were censused were occupied by ''A. percula'' and ''A. perideraion''. 
''A. percula'' generally occupies anemones that are near shore, while ''A. perideraion'' occupies anemones that are more offshore. Anemonefish do not occupy anemones if they are in shallow water or if they are too small. Shallow waters are not an inhabitable environment for ''A. percula'' because of the lower salinity levels, increased temperatures, and exposure during low tides. Also, small anemones would not provide protection from predators.<ref name=Elliot01/>  ''A. percula'' and the host anemone are very important to one another and interact in a symbiotic relationship. ''A. percula'' cleans the host anemone by consuming algae residue and zooplankton such as [[copepod]]s and larval [[tunicate]]s. They also protect the anemone from polyp-consuming fish and other predators, while the clownfish is protected from predators by the anemone. ''A. percula'' sometimes carries pieces of food to the host anemone for later consumption. In most cases the host anemone then devours the food that ''A. percula'' stored around it.<ref name=Lee03/> Chances of survival for both parties involved are increased through this co-existence.

The larvae of orange clownfish use [[olfaction]] to avoid predators, and increased [[ocean acidification]] may cause larvae to be unable to differentiate predators from other odors.<ref>{{Cite journal|last1=Dixson|first1=Danielle L.|last2=Munday|first2=Philip L.|last3=Jones|first3=Geoffrey P.|date=January 2010|title=Ocean acidification disrupts the innate ability of fish to detect predator olfactory cues |journal=Ecology Letters |language=en |volume=13 |issue=1 |pages=68–75 |doi=10.1111/j.1461-0248.2009.01400.x|pmid=19917053|bibcode=2010EcolL..13...68D }}</ref> This could allow them to be preyed upon more easily, and lead to higher population mortality rates. Impairment of larval olfaction may also make them less able to locate appropriate reef habitats at the higher levels of ocean acidification that are projected to occur with increased carbon dioxide emissions.<ref>{{Cite journal|last1=Munday|first1=Philip L.|last2=Dixson|first2=Danielle L.|last3=Donelson|first3=Jennifer M.|last4=Jones|first4=Geoffrey P.|last5=Pratchett|first5=Morgan S.|last6=Devitsina|first6=Galina V.|last7=Døving|first7=Kjell B.|last8=Karl|first8=David M. |display-authors=4 |date=2009|title=Ocean Acidification Impairs Olfactory Discrimination and Homing Ability of a Marine Fish|journal=Proceedings of the National Academy of Sciences of the United States of America|volume=106|issue=6|pages=1848–1852|doi=10.1073/pnas.0809996106|jstor=40421685|pmid=19188596|pmc=2644126|bibcode=2009PNAS..106.1848M |s2cid=569462|issn=0027-8424|doi-access=free}}</ref> A paper published in [[Nature (journal)|''Nature'']] in 2020 cast doubt on the effect of acidification, stating "our findings indicate that the reported effects of ocean acidification on the behaviour of coral reef fishes are not reproducible, suggesting that behavioural perturbations will not be a major consequence for coral reef fishes in high CO2 oceans".<ref>{{Cite journal |last1=Clark |first1=Timothy D |last2=Raby |first2=Graham D |last3=Roche |first3= Dominique G |last4=Binning |first4=Sandra A |last5=Speers-Roesch |first5=Ben |last6=Jutfelt |first6=Fredrik |last7=Sundin |first7=Josefin |display-authors=4 |date=2020 |title=Ocean acidification does not impair the behaviour of coral reef fishes |journal=[[Nature (journal)|Nature]] |volume=577 |issue=7790 |pages=370–375 |doi=10.1038/s41586-019-1903-y|pmid=31915382 |bibcode=2020Natur.577..370C |s2cid=210118722 |url=https://figshare.com/articles/preprint/Ocean_acidification_does_not_impair_the_behaviour_of_coral_reef_fishes/11625570 |url-access=subscription }}</ref><ref>{{cite web |url=https://www.science.org/content/article/does-ocean-acidification-alter-fish-behavior-fraud-allegations-create-sea-doubt |title=Does ocean acidification alter fish behavior? Fraud allegations create a sea of doubt |first=Martin |last=Enserink |date=May 2021 |access-date=12 May 2021 |website=sciencemag.org}}</ref> A [[meta-analysis]] published in 2022 also found that [[effect size]]s of studies assessing ocean acidification effects on fish behaviour have declined dramatically over a decade of research on this topic, with effects appearing negligible since 2015, representing one of the most extreme examples of the [[decline effect]] in ecology.<ref>{{Cite journal |last1=Clements |first1=Jeff C. |last2=Sundin |first2=Josefin |last3=Clark |first3=Timothy D. |last4=Jutfelt |first4=Fredrik |date=2022-02-03 |title=Meta-analysis reveals an extreme "decline effect" in the impacts of ocean acidification on fish behavior |journal=PLOS Biology |language=en |volume=20 |issue=2 |article-number=e3001511 |doi=10.1371/journal.pbio.3001511 |issn=1545-7885 |pmc=8812914 |pmid=35113875 |doi-access=free }}</ref>

==Development==
The development of ''A. percula'' is relatively fast. After the eggs are fertilized, they are ready to hatch after about 6–7 days. After hatching, the larvae are very small and are transparent except for the eyes, [[yolk sac]], and a few colors across the body. The larvae then sink to the benthic environment, but then swim to the upper water column. The larvae spend about a week floating among plankton and are transported by ocean currents.<ref name=Lee03/> The larval stage ends when ''A. percula'' settles to the bottom of the ocean. The process from larval stage to juvenile takes about one day. Rapid development of color occurs during ''A. percula'''s juvenile stage. During the juvenile stage the anemonefish has to find a suitable anemone host. Specific chemical components are used when finding their host. These chemical cues are different for each anemonefish. This causes preferential selection when finding their anemone host species.<ref name=Lee03/> When ''A. percula'' comes in contact with the anemone, it produces a protective [[mucus|mucous]] coat. This mucous coat is developed with multiple interactions with the host anemone. ''A. percula'' dances around the anemone, touching its fins first to the tentacles and then its entire body during its first interaction with the anemone. This process could take a few minutes or up to several hours.<ref name=Lee03/> If ''A. percula'' does not continue to come in contact with the host anemone, the protective mucus may disappear. ''A. percula'' belongs to a group of fishes that are not stung by the [[nematocyst]]s of the anemone. If ''A. percula'' did not have the protective mucous covering, it would be stung. Other fish species that lack the mucous covering are consumed by the anemone.<ref name=Lee03/>

==See also==
*[[Picasso clownfish]]

==References==
{{Reflist}}

== External links ==
{{Wikispecies|Amphiprion percula}}
{{Commons category|Amphiprion percula}}
* {{ITIS |id=170144 |taxon=Amphiprion percula}}
* {{WRMS species|278402|''Amphiprion percula''| Lacepède, 1802}}
*[http://www.aquamaps.org Native habitat data from ''AquaMaps'']
* {{SealifePhotos|278402}}

{{Taxonbar|from=Q926234}}

[[Category:Amphiprion|orange clownfish]]
[[Category:Fish of Palau]]
[[Category:Fish of Oceania]]
[[Category:Fish described in 1802|orange clownfish]]