CLOWN FISH: CHARACTERISTICS, HABITAT, FEEDING, BEHAVIOR - BIOLOGY - 2025

The clownfish is a marine animal that belongs to the genus Amphiprion. Its main characteristic is the bright coloration of its body, which can be orange, red, yellow, pink or black. On these tones, several white stripes stand out, demarcated by fine black lines.

It is distributed in the coral reefs of the Indian and Pacific oceans. There, they form a microhabitat with the sea anemones, within which they live. With these, the clownfish establishes a symbiotic relationship, benefiting from the protection offered by its tentacles.

Clownfish. Source: pixabay.com

Also, thanks to this relationship, it can obtain prey and food scraps, which allow it to feed. On the other hand, the fish serves as a lure to other fish, which are eaten by the anemone. In addition, it can eliminate the parasites that are there and defend the host from its main predator, the butterflyfish.

The anemone fish, as it is also known, is born with immature male and female sex organs. Because of this, you can change sex, as required.

This animal has a hierarchical social relationship. The group is led by the largest of the females, followed by a breeding male, the second in size of the group.

characteristics

Nhobgood Nick Hobgood

Stages of development

The unfertilized egg is semitransparent and the yolk occupies a large space within it. At one of its ends, identified as the animal pole, it is attached to the substrate using filamentous stems, which have a glutinous substance.

Embryonic period

This begins with the fertilization of the eggs, which were covered with a transparent and smooth chorion. These are between 1.5 and 3 millimeters long and 0.8 to 1.84 millimeters wide.

This stage is characterized by the fact that the yolk feeds endogenously. In addition, to identify the levels of development, this period is divided into three phases: cleavage, embryonic, and embryonic eleuthero.

Hatching

Incubation of the eggs generally occurs after sunset, peaking during hours of complete darkness.

The embryo begins hatching at the moment it begins to make a vigorous wave movement, in which the body and the caudal area move rhythmically. Thanks to this, the egg capsule breaks, the embryo's tail emerging first.

Larval period

The larval stage begins with the transition of the larva to exogenous nutrition and ends with the ossification of the axial skeleton.

Another characteristic of this phase is the persistence of some embryonic organs, which will be replaced by others permanently or could disappear, in the event that the structure is not functional.

Youth period

This period begins when the fins are completely differentiated and the vast majority of the temporal organs are replaced by the definitive organs. The stage culminates when the maturation of the gametes begins.

The transition from larva to fish involves notable changes. However, some of the organic structures, such as scales and intrusive organs, develop in the juvenile stage.

All juveniles stop being pelagic feeders to be epibenthic. This is how they eat shrimp, mussel meat and fish.

Sub adult period

It begins with the first stage of gamete maturation and is characterized by very rapid growth. In this stage, the young show aggression towards subordinates, with respect to the territory and the spawning area.

Adult period

The main factor that identifies the adult is the maturation of the gametes, which allows reproduction. In the female, the first spawning (laying of eggs) occurs when they are 70 to 80 millimeters long, about 18 months after the egg has hatched. The male matures when it reaches a length of 58 to 654 millimeters.

Senescent period

As clownfish age, their egg production, spawning frequency, and growth rate decline. Regarding egg laying and growth, they stopped 6 to 7 years after the first spawning occurred.

Coloration

Clownfish coloration varies by species. The base shade could be reddish brown, bright orange, black, yellow, or brownish pink. A particular characteristic of this genre are the stripes that vertically cross its body. These could be one, two, or three.

They are generally white, although in Amphiprion chrysopterus, they are bluish. Likewise, they are delimited by thin black lines.

palma aquarium There are also peculiarities of each species. Thus, the Amphiprion perideraion has a white line that runs through its upper part, ranging from the tail fin to the head. In addition, it has only a narrow vertical stripe, between the pectoral fins and the head.

The Amphiprion sandaracinos also has a horizontal white line on the back, but this is born on the upper lip.

As for the Amphiprion ocellaris, its body is orange to reddish brown. However, in the northern part of Australia you can find black species. It has three vertically oriented white stripes, framed with a thin black line.

The first stripe is behind the eyes, the second is located in the middle of the body, and the last one surrounds the tail. Likewise, all its fins are bordered in black.

Head

On each side of the head it has a nostril. Its mouth, which is small, contains a pharyngeal plaque. In relation to the teeth, they could be arranged in one or two rows.

Clown fish and anemone. pixabay.com

The shape of these could resemble an incisor tooth, especially in those forms that graze algae. They could also be conical, typical of those that trap small organisms.

Body

The body of the clownfish is oval in shape and laterally compressed, giving it a rounded profile. It has a unique dorsal fin, with a total of 8 to 17 spines and 10 to 18 soft rays. As for the anal fin, it can have between two or three spines.

The caudal is generally rounded, which makes it ineffective for rapid swimming. However, in Amphiprion clarkii, the tail is emarginated or truncated, with which it can swim with a little greater speed.

Size

Within the genus Amphiprion, the largest ones can reach a length of 18 centimeters, while the smallest ones could measure between 10 and 11 centimeters.

Neurotoxin immunity

The clownfish has adaptations that allow it to live among the tentacles of sea anemones. The skin of this animal secretes a thick layer of mucus that protects it from cnidocytes. These are stinging cells present in the anemone's tentacles, which contain paralyzing neurotoxins.

This mucus usually contains high proportions of glycoproteins and lipids. However, in this order of marine fish, the mucous layer is thicker and thicker. Clownfish are not born immune to the anemone toxin, but the mucus prevents the body from absorbing the toxic substance in large quantities.

Thus, the small doses that can enter your body make you immune. There is probably a period of acclimatization before the fish becomes immune to the anemone sting. To achieve this, this animal swims around the anemone and rubs its fins and belly against the ends of the tentacles.

Taxonomy and subspecies

Animal Kingdom.

Subkingdom Bilateria.

Phylum Cordano.

Vertebrate Subfilum.

Infrafilum Gnathostomata.

Actinopterygii superclass.

Teleostei class.

Superorder Acanthopterygii.

Perciformes order.

Suborder Labroidei.

Family Pomacentridae.

Genus Amphiprion.

Species:

Habitat and distribution

Ithamalfonso, melog Amphiprion lives in warm waters, mainly marine, of all tropical seas. Thus, it is distributed in the eastern and western region of the Indian Ocean, east of the Pacific Ocean and from Australia to the Solomon Islands.

In Indonesia you can find the largest number of species, while in Australia, there are unique clownfish, such as Amphiprion ocellaris, which is black in color.

www.youtube.com/watch?v=9xo9RJ6vWAEL Members of this genus do not inhabit the Mediterranean, the Caribbean or the Atlantic Ocean. In Asia, it is located in the Chagos Archipelago, China, India, the Andaman and Nicobar Islands, Indonesia, Nusa Tenggara, Japan, the Ryukyu Archipelago, Malaysia, the Philippines, Singapore, Taiwan, Thailand and Vietnam.

In relation to Africa, it lives in Aldabra, Mauricius and Seychelles. In Oceania, it lives in Australia, North Australia, Queensland, Fiji, Kiribati, Marshall Islands, Micronesia, Federated States of, New Caledonia, Papua New Guinea, Solomon Islands, Tonga, and Vanuatu.

In these regions it is found in shallow areas, related to tropical or sandy coral reefs, although it is always associated with sea anemones.

It lives in shallow waters, between 1 and 18 meters. However, Amphiprion perideraion can live in deeper pond waters, approximately 38 meters.

Climate change

Carlos Fernández San Millán The variations that are occurring in the state of the climate system affect all the world's ecosystems in various ways.

Regarding the impact of these on the clownfish, there is the incidence on their natural habitat, the coral reefs. In addition, it alters the chemistry and temperature of the water.

Loss of habitat due to the decline of coral reefs

The current level of CO2, causes that the coral reefs are diminishing, reason why they could disappear. In the event that high levels of CO2 increase, these ecosystems will be in a violent decline, due to the acidification of the oceans, among other factors.

Clownfish depend on sea anemones, which are frequently found on coral reefs. Because of this, populations of this fish could be severely affected if reefs decline.

In 1998, a global coral bleaching occurred, leading to the complete extinction of various species of sea anemones that existed on Sesoko Island in Japan. This caused the decrease of the population of Megaptera novaeangliae that inhabited this region.

Navigation problems due to ocean acidity

Specialists have shown that the increase in the level of acidity of the ocean affects the ability of the clownfish to identify the chemical signals, necessary to locate and navigate towards the anemone where it lives.

This situation is particularly serious in the young, since being unable to locate a host they are exposed to predators. In addition, it could influence their reproduction, since it hinders their opportunity to mate.

Although in the adult fish the loss of the chemical signal may be a minor problem, it could confuse it and cause it to lose its return route, when it goes out to explore outside the anemone in search of food.

Alterations in development rates

Fish are ectothermic, so the reproductive behavior of Megaptera novaeangliae is affected by the warming of the oceans. This fish breeds within a small temperature range. An increase in this factor could cause, among other things, that the eggs perish.

Because of this, members of the genus Amphiprion could migrate to colder waters. However, the larvae can travel only short distances, so their dispersal to other waters would be limited.

Reproduction

The clownfish are born with immature male and female sex organs. This species has the ability to change sex, which depends on environmental conditions.

Because clownfish are protandric hermaphrodites, male sex organs mature first. This could lead to the misperception that all of this species are born male.

During courtship, the male attracts the female by spreading his fins and swimming rapidly down and up. Also, it can chase him and nibble on some parts of his body.

Before spawning, the male selects the place where he is going to build the nest, cleaning it with his mouth. This can be located on a rock near or within a sea anemone, in such a way that its tentacles protect the eggs.

Mating and spawning

Reproduction occurs at any time of the year. Spawning is preceded by a bulging of the female's abdomen and by the bulge, in both sexes, of the genital tubes.

In the female there is a conical papilla 4 to 5 millimeters long and white in color. This is located in the urogenital sinus, as part of the ovipositor. As for the male, it shows a urogenital duct that extends from the cloaca and measures approximately 2 millimeters.

The eggs are expelled while the female swims in a zig zag fashion and rubs her belly against the nest. Once in the water, the eggs adhere to the substrate. A female can lay between 100 and 1000 eggs, depending on her age.

On the other hand, the male, closely following the female, fertilizes the eggs as soon as they are deposited in the nest.

The eggs are capsule-shaped and orange in color. As it develops, it darkens, because the yolk is consumed. Before hatching, they have a silver hue and larvae are observed.

Parental care

The incubation process is affected by the temperature of the water. Thus, while the water has a lower temperature, the incubation time will be longer.

During the incubation stage, both parents eat dead eggs or those that were not fertilized. Those that are fertilized are cared for until they are born. One of the behaviors they perform is fanning them, waving their pectoral fins for this. In addition, they remove the particles that cover them with their mouth.

The male assumes an important role in the care and protection of the eggs, spending more time in the nest than the female. Progressively, as the incubation time approaches, the female stays in the nest increases.

Between 8 and 12 days later the eggs hatch and the young disperse, floating in ocean currents. At this stage, the young can be easily eaten by predators. However, after about two weeks, the survivors begin to explore the reefs near the sea anemones.

Feeding

The clownfish is a generalist omnivorous animal, whose diet is made up of 34% plants and 44% benthic invertebrates. Thus, their diet is made up of algae, worms, isopods, zooplankton, copepods and small crustaceans.

In addition, it can eat the dead tentacles of the anemone and any prey not ingested by it. Also, the species of the genus Amphiprion consume the parasites that inhabit it.

In food, there is the domain of a hierarchical structure, within the group that inhabits an anemone. The smaller fish receive a greater amount of aggression by the members of the group.

This results in them needing to reduce the energy they will invest in swimming long distances to find food. Therefore, they remain close, where the interspecific competition in much greater. Also, it is not safe for youngsters to walk away from the safety of being around the anemone.

As for the larger fish, they travel greater distances in search of food, but generally they do not go more than several meters from the place where they are grouped. However, they could also choose to stay in place and wait for prey to approach the anemone.

Behavior

One of the main characteristics of the clownfish is its territorial behavior, so it can occasionally become aggressive. In relation to its social structure, there are hierarchies. The most aggressive and largest female is at the highest level.

The basic social unit consists of a female, the largest, the reproductive male, and other non-reproductive clownfish, whose sexual organs have not developed.

In the event that the female dies, the second largest member of the group will become female and the largest member of the non-reproductive group will develop male organs. In this way she will take the place of the reproductive male of the group.

Generally, youngsters have a hard time finding a sea anemone to live in. This happens because in each anemone there is also a hierarchy. Thus, when a new young person enters, they are located at the bottom of the social scale.

Most likely this causes it to be a victim of other clown fish, which could cause its exit from that anemone.

Symbiosis with the sea anemone

Members of the genus Amphiprion have a close symbiotic relationship with the sea anemone, especially with the species Heteractis magnifica, Stichodactyla mertensii, Stichodactyla gigantea.

However, there are other anemones that offer a microhabitat to this marine fish. Among these are: Cryptodendrum adhaesivum, Entacmaea quadricolor, Macrodactyla doreensis, Heteractis aurora, Heteractis crispa, Heteractis Malu and Stichodactyla haddoni.

Clownfish use anemones to shelter and protect themselves from the various threats that afflict them. These animals are not characterized by being expert swimmers, so when they are in open water, they are easy prey for predators, among which are eels.

The anemone's tentacles contain numerous stinging cells or nematocysts that the animal uses to immobilize its prey. This is how the clownfish found inside the anemone avoid being caught. In addition, anemones also offer protection to nests.

Guest benefits

In return, the clownfish cleans out the parasites found on the anemone's body and prevents the butterflyfish from devouring its tentacles. On the other hand, its bright coloration could attract other smaller fish to the anemone, which it will then catch for ingestion.

The nitrogen excreted by clownfish increases the amount of algae that are incorporated into the body of its hosts, which contributes to the regeneration of their tissues and their growth.

Likewise, the activity of the Amphiprion causes a greater circulation of the water that is around the anemone. The aeration of the tentacles offers benefits to the host and at the same time oxygenates the water.

References

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