Clownfish, Amphiprion sp. (Biology – Clownfish and anemone – changing sex) – Video

This video was filmed in Alexandria marine aquarium (National Institute of Oceanography and Fishery), Egypt

Clownfish includes a group of species that belongs to the family Pomacentridae. These species whether caught from the wild or bred in captivity make up about 40% of the global marine ornamental trade. They are about 30 known species which are native to warmer waters and are found around tropical coral reefs; most of which live in the shallow waters of the Indian Ocean, the Red Sea, and the western Pacific.

These fishes are characterized by their bright yellow to orange color with three distinctive white bars across its body. They are among the most recognizable reef-dwellers. Their average length –as reported- ranges about 11 cm.

Feeding habits: Clown fish are omnivorous animals that they eat a wide range of food such as algae, plankton, molluscs and small crustaceans. They also feed on left-over or undigested food from their host anemones.

Clownfish and anemone relationship: The clownfish and anemones represent a model of symbiotic relationship in which both parties benefit of such relationship. In order to establish such relationship, the clownfish has to acquire an immunity to protect them against the stings of their host (anemone). The protection develops in a form of a layer of mucus or slime coating which protects the clownfish against the anemone’s lethal sting making the fish as one of a few fish that can swim freely between the poisonous tentacles of an anemone without being stung. The protective slime is a mixture between the slime of the anemone with its stinging cells and its own skin slime.  

The benefits of such symbiotic relationship could summarize what benefits each party gets. The anemone provides a safe home for the clownfish where most fish other than clown fish avoid these stinging anemones. In return, the clownfish will eat the remains of fish paralyzed and eaten by the anemone. The clownfish eats the rotten or dead tentacles of the anemones and could also feed on small invertebrates that could harm the anemone.

The clownfish sticks close to their anemone host which provides them with enough protection to the predation if they move far away by large fish species such as sharks and eels).

Changing sex and reproduction:  All clownfish are born male. They have the ability to switch their sex, but will do so only to become the dominant female of a group. When the female dies, the largest male in the area will take her place and becomes the breeding female. This phenomenon is known as protandrous hermaphrodites.

Female clownfish lays her eggs in hundreds or thousands depending on species. Eggs are laid on flat surfaces close to their host anemone. The male parent will usually guard the eggs until they hatch in about 6 to 10 days depending on water temperature. The male continues to take care of the hatched fry until they reach sexual maturity.

The spawning and hatching follow the lunar clock. It is believed that the nocturnal hatching during high tide may reduce predation by allowing for a greater capacity for escape.


References: Wikipedia, Gender and life, National Geographic, Shedd (The World’s Aquarium), Sea Life, a-z animals




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