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The ocellaris clownfish (''Amphiprion ocellaris''), also known as the false percula clownfish or common clownfish, is a
marine fish Saltwater fish, also called marine fish or sea fish, are fish that live in seawater. Saltwater fish can swim and live alone or in a large group called a school. Saltwater fish are very commonly kept in aquariums for entertainment. Many saltwater f ...
belonging to the
family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
Pomacentridae Pomacentridae is a family of ray-finned fish, comprising the damselfishes and clownfishes. This family were formerly placed in the order Perciformes but are now regarded as being ''incertae sedis'' in the subseries Ovalentaria in the clade Perco ...
, which includes
clownfish Clownfish or anemonefish are fishes from the subfamily Amphiprioninae in the family Pomacentridae. Thirty species of clownfish are recognized: one in the genus ''Premnas'', while the remaining are in the genus ''Amphiprion''. In the wild, th ...
es and
damselfish Damselfish are those within the subfamilies Abudefdufinae, Chrominae, Lepidozyginae, Pomacentrinae, and Stegastenae within the family Pomacentridae. Most species within this group are relatively small, with the largest species being about 30 ...
es. ''Amphiprion ocellaris'' are found in different colors, depending on where they are located. For example, black ''Amphiprion ocellaris '' with white bands can be found near northern Australia, Southeast Asia, and Japan. Orange or red-brown ''Amphiprion ocellaris ''also exist with three similar white bands on the body and head. ''Amphiprion ocellaris ''can be distinguished from other ''Amphiprion'' species based on the number of pectoral rays and dorsal spines. ''Amphiprion ocellaris ''are known to grow about 110 mm long. Like many other fish species, females are, however, larger than males. The life cycle of ''Amphiprion ocellaris ''varies in whether they reside at the surface or bottom of the ocean. When they initially hatch, they reside near the surface. However, when ''Amphiprion ocellaris'' enter into the juvenile stage of life, they travel down to the bottom to find shelter in a host anemone. Once they find their anemone, they form a
symbiotic relationship Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasit ...
with them.


Phylogeny

The species ''Amphiprion ocellaris'' belongs to the class
Actinopterygii Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or h ...
which contains bony
Teleost Teleostei (; Greek ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as teleosts ), is, by far, the largest infraclass in the class Actinopterygii, the ray-finned fishes, containing 96% of all extant species of fish. Tel ...
fish and other ray-finned fish. ''A. ocellaris'' is the most basal species in the genus ''Amphiprion'' which is closely related to the genus ''
Premnas ''Premnas biaculeatus'', commonly known as spine-cheeked anemonefish or the maroon clownfish, is a species of anemonefish found in the Indo-Pacific from western Indonesia to Taiwan and the Great Barrier Reef.Lieske, E., and R. Myers. 1999. ''C ...
''. The species' most closely related ancestor is ''
Amphiprion percula The orange clownfish (''Amphiprion percula'') also known as percula clownfish and clown anemonefish, is widely known as a popular aquarium fish. Like other clownfishes (also known as anemonefishes), it often lives in association with sea anemones. ...
'', the orange clownfish. It is thought that ''A. ocellaris'' specialized after diverging from the genus ''Premnas'', and scientific evidence confirms that all clownfish belonging to the genus ''Amphiprion'' initially could withstand the stings of only one type of anemone; after further
speciation Speciation is the evolutionary process by which populations evolve to become distinct species. The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution within ...
the 28 different species of clownfish including ''A. ocellaris'' have specialized to be able to resist the poisonous stings of many different anemone species.


Description

The common clownfish is a small fish which grows up to 11 cm (4.3 inches). Its body has a stocky appearance and oval shape. It is compressed laterally, with a round profile. The coloration of its body is orange to reddish-brown, but it can also be black in some particular areas such as the
Northern Territory The Northern Territory (commonly abbreviated as NT; formally the Northern Territory of Australia) is an states and territories of Australia, Australian territory in the central and central northern regions of Australia. The Northern Territory ...
in
Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
. It has three vertical white stripes outlined with a fine black line. The first passes just behind the eye, the second in the middle of the body widens forward to the head centrally and the third one circles the
caudal peduncle Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...
. All the fins are also outlined with a fine black line. ''A. ocellaris'' is often confused with ''Amphiprion percula'', which possesses exactly the same colours and patterns at first sight but distinguishes itself by the thickness of the black outlines. Additionally, ''A. ocellaris'' has a taller dorsal fin, and typically possesses 11 dorsal-fin spines vs. 10 spines in ''Amphiprion percula''.


Distribution and habitat

This species is found in the Eastern
Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by th ...
and in the western
Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...
. As mentioned earlier, they can also be found in Northern Australia, Southeast Asia and Japan. ''Amphiprion ocellaris'' typically lives in small groups on outer
reef A reef is a ridge or shoal of rock, coral or similar relatively stable material, lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic processes— deposition of sand, wave erosion planing down rock out ...
slopes or in sheltered
lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') a ...
s at a maximal depth of 15 meters. It inhabits three different
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
of
sea anemone Sea anemones are a group of predation, predatory marine invertebrates of the order (biology), order Actiniaria. Because of their colourful appearance, they are named after the ''Anemone'', a terrestrial flowering plant. Sea anemones are classifi ...
s: ''
Heteractis magnifica ''Heteractis magnifica'', also known by the common names magnificent sea anemone or Ritteri anemone, is a species of sea anemone belonging to the Stichodactylidae family native to the Indo-Pacific area. Description The magnificent sea anemone is ...
'', ''
Stichodactyla gigantea ''Stichodactyla gigantea'', commonly known as the giant carpet anemone, is a species of sea anemone that lives in the Indo-Pacific area. It can be kept in an aquarium but is a very challenging species to keep alive and healthy for more than 3– ...
'' and ''
Stichodactyla mertensii ''Stichodactyla mertensii'', commonly known as Mertens' carpet sea anemone, is a species of sea anemones in the family Stichodactylidae. It is regarded as the largest sea anemone with a diameter of over , the next largest being ''Heteractis mag ...
''and have symbiotic relationships with the anemone.


Behavior

''A. ocellaris'' is a diurnal fish. It is a
protandrous hermaphrodite Sequential hermaphroditism (called dichogamy in botany) is a type of hermaphroditism that occurs in many fish, gastropods, and plants. Sequential hermaphroditism occurs when the individual changes its sex at some point in its life. In particular, ...
, which means the male can change its sex to female during its life, and lives in a harem in which an established dominance hierarchy manages the group and keeps individuals at a specific social rank. It is aggressively territorial and is completely dependent on its sea anemone.


Shelter

''A. ocellaris'' are reliant on sea anemone for shelter (they have a symbiotic relationship with the sea anemone). Sea anemone are protection for the fish and their nests. This is because when ''A. ocellaris'' are in the open waters, they have a higher risk of predation. It is postulated that the fanning behavior of the fish and removal of parasites promotes the health of
sea anemones Sea anemones are a group of predatory marine invertebrates of the order Actiniaria. Because of their colourful appearance, they are named after the ''Anemone'', a terrestrial flowering plant. Sea anemones are classified in the phylum Cnidaria, ...
which contain ''A. ocellaris'' fish. In addition, the anemone provides protection for the fish with its tentacles, however, the fish's mucus protection prevents it from being stung by the tentacles.Allen, G. 1997. Marine Fishes of Tropical Australia and South-East Asia. Perth: Western Australian Museum.Myers, R. 1999. Miconesian Reef Fish: A Field Guide for Divers and Aquarists. Barrigada: Territory of Guam: Coral Graphics. The presence of the clownfish can be interpreted as a lure to attract potential anemone's preys close to the
tentacle In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work main ...
s. And the clownfish can also defend the anemone against some reef fishes which could eat the tentacles.


Social system

Social systems can be defined as society considered as a system organized by a characteristic pattern of relationships. ''A. ocellaris'' form specific social hierarchies within their societies. These social hierarchies result in competition to travel between the different levels of society, which is seen between various ages as well.


Queue selection

Queues is the term for social groups of ''A. ocellaris''. This is because these fish form social hierarchies, or social rank, by outliving the more dominant members of the group. The dominant pair of each queue reproduces more compared to the subordinate fishes. This is the reason for why these individuals should adopt various tactics in which they increase their probability of attaining social dominance. There are two types of ''A. ocellaris'', settlers and switchers. Settlers prefer shorter queues, while switchers will usually move after settlement. However, studies show that there is no difference in the characteristics between switchers and non-switchers, and there is no data demonstrating that ''A. ocellaris'' utilize the switching tactic for dominance. Although settlement preferences increase the likelihood of gaining social dominance, switching could have the function of increasing social dominance benefits after social dominance has been acquired.


Juvenile ''Amphiprion ocellaris''

Juvenile ''A. ocellaris'' have difficulty finding a sea anemone to live in (since they need anemone for survival and shelter). The difficulty also arises in the fact that there exists a hierarchy in each anemone. Thus, when a new juvenile enters an anemone, it begins at the bottom of the social ladder where it is often the victim of aggression by other clownfish. This aggression from other ''A. ocellaris'' in the anemone can cause the juvenile to be chased out of the anemone, and left to search for another anemone.Thresher, R. 1984. Reproduction in Reef Fishes. New Jersey: T.F.H. Publications, Inc..


Group size and patch size

Studies have shown that there is a correlation between the size of the group and the size of the patch; however this correlation provides no implication that subordinate group members have less resources. More likely, it is the effects of the patch size on the group member that dominates interactions. An experiment was performed to study the mechanism responsible for the positive correlation between the group size and patch size. The scientists argued that the correlation between the group size and patch size is because of the indirect consequence of the positive relationship between the dominant group member's length and the anemone size. The length of the dominant group member limits the group size because the length of the dominant group member prevents the group of the subordinate group members. This data shows that the patch size and group size correlation does not necessarily imply the decrease in resources of group members subordinate to the dominant group member.


Food habits

''A. ocellaris'' feed on
plankton Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankt ...
and
algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...
, thus they are considered omnivores. Feeding is also affected by the hierarchy in ''A. ocellaris'' groups. Since the smaller, less dominant fish face aggression from the more aggressive fish, they have less energy to forage for food. Thus, they usually do not eat as much as the dominant fish do, because of reduced energy, but also because of the increased danger they face when they leave their anemone since they are smaller. In other words, the larger fish will usually travel farther than the smaller fish. Generally, the ''A. ocellaris'' feed on algae, copepods, and zooplankton.


Reproduction and life history

''A. ocellaris ''have reproductive behaviors very similar to that of all
anemonefish Clownfish or anemonefish are fishes from the subfamily Amphiprioninae in the family Pomacentridae. Thirty species of clownfish are recognized: one in the genus '' Premnas'', while the remaining are in the genus '' Amphiprion''. In the wild, t ...
. They have monogamous mating systems, and in their spawning processes, they also have different levels of aggressiveness between males and females. In addition, there is a reproductive hierarchy that exists between age and sex.


Spawning

There is not much data on the reproduction of ''A. ocellaris''. However, similar behaviors throughout all anemone fishes have been recorded. These fish have
monogamous Monogamy ( ) is a form of Dyad (sociology), dyadic Intimate relationship, relationship in which an individual has only one Significant other, partner during their lifetime. Alternately, only one partner at any one time (Monogamy#Serial monogamy, ...
mating systems, and are territorial of their anemone. Males become more aggressive during
spawning Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquati ...
. Male behavior also changes to attract females: biting, chasing, fin extension. Before spawning, the male prepares the nest near the anemone (so that the tentacles of the anemone can protect the nest). After the male chases the female to the nest, the female begins the spawning process. She lays eggs for about one to two hours, and then leave the nest for the male to fertilize the eggs. The eggs take approximately six to eight days to hatch (this time period can be affected by the temperature of water). Because of the
external fertilization External fertilization is a mode of reproduction in which a male organism's sperm fertilizes a female organism's egg outside of the female's body. It is contrasted with internal fertilization, in which sperm are introduced via insemination and then ...
, males usually care for the eggs. They also have responsibilities for eating fungi-infected or infertile eggs, and fanning the eggs.


Reproductive hierarchy

All anemonefish are protandrous hermaphrodites, meaning they first develop into males and may become females later in life. Anemonefish exhibit
phenotypic plasticity Phenotypic plasticity refers to some of the changes in an organism's behavior, morphology and physiology in response to a unique environment. Fundamental to the way in which organisms cope with environmental variation, phenotypic plasticity encompa ...
when males, females, and juveniles inhabit the same anemone. In an anemonefish social group, the female is the dominant and largest member, followed by the dominant male, while other anemonefish remain non-reproductive.Fricke, H., S. Fricke. 1977. Monogamy and sex change by aggressive dominance in coral reef fish. Nature, 266: 830-832. One experiment placed three juvenile anemonefish in a tank and observed their behaviors over the course of a month. The researchers drew conclusions about the fish's social hierarchy based on signs of dominance such as aggressive or appeasing behaviors, occupation of territory in the tank, and body mass increase. The dominant fish grew larger compared to lower-ranked fish, suggesting the lower-ranked fish experienced growth suppression. In addition, a difference in the fish's levels of certain steroids suggested that lower-ranked individuals also experienced reproductive suppression. Another experiment demonstrated that when a female anemonefish is removed from the anemone, then the dominant male becomes the female and the next-highest-ranked male moves up the
dominance hierarchy In biology, a dominance hierarchy (formerly and colloquially called a pecking order) is a type of social hierarchy that arises when members of animal social animal , social groups interact, creating a ranking system. A dominant higher-ranking i ...
to become the dominant male. Females use aggressive dominance behavior to control the males, preventing the formation of other females, and dominant males prevent juvenile males from mating.


In aquaria

In nature, the false percula clownfish is hosted by ''Heteractis magnifica'' and ''Stichodactyla gigantea''. However, in captivity in a
reef aquarium A reef aquarium or reef tank is a marine aquarium that prominently displays live corals and other marine invertebrates as well as fish that play a role in maintaining the tropical coral reef environment. A reef aquarium requires appropriately ...
, the false percula is hosted by other species of anemone, including ''
Entacmaea quadricolor Bubble-tip anemone (''Entacmaea quadricolor'') is a species of sea anemone in the family Actiniidae. Like several anemone species, ''E. quadricolor'' can support several anemonefish species, and displays two growth types based on where they live ...
''. In addition, clownfish may adopt a surrogate host as opposed to an anemone, such as ''
Euphyllia divisa Euphyllia divisa (reclassified in 2017 as Fimbriaphyllia divisa), commonly known as frogspawn coral and sometimes misspelled ''Euphyllia divisia'', is a large-polyped stony coral native to the Indo-Pacific islands. It is a commonly kept species ...
'', xenia coral, etc.


Human interaction

''A. ocellaris'' are utilized as part of the tropical fish aquarium trade. However, only certain colors are in demand. In addition, ''A. ocellaris'' are used in research since they can be bred easily.Sadovy, Y., A. Vincent (2002). "Ecological Issue and the Trade in Live Reef Fishes". pp. 395 in P Sale, ed. ''Coral Reef Fishes''. San Diego, California: Academic Press. This high demand in trade has been dangerous for ''A. ocellaris'' population due to
overexploitation Overexploitation, also called overharvesting, refers to harvesting a renewable resource to the point of diminishing returns. Continued overexploitation can lead to the destruction of the resource, as it will be unable to replenish. The term app ...
.


Popular culture

The main characters Marlin and his son Nemo from the animated film ''
Finding Nemo ''Finding Nemo'' is a 2003 American computer-animated comedy-drama adventure film produced by Pixar Animation Studios and released by Walt Disney Pictures. Directed by Andrew Stanton with co-direction by Lee Unkrich, the screenplay was writ ...
'', and its sequel ''
Finding Dory ''Finding Dory'' is a 2016 American computer-animated comedy-drama adventure film produced by Pixar Animation Studios and released by Walt Disney Pictures. Directed by Andrew Stanton, produced by Lindsey Collins and written by Stanton and Vict ...
'' (as well as Nemo’s late mother Coral), are ocellaris clownfish.


See also

*


References


External links

* * * *
Aquaticdatabase entry for ''Amphiprion ocellaris'' (Ocellaris Clownfish).

Photo Gallery of ''Amphiprion ocellaris'' and their eggs
(ger.) * Aquarium Wiki care information on Amphiprion ocellaris * * {{Authority control Amphiprion Fish described in 1802 Taxa named by Georges Cuvier Articles containing video clips