Anemone fishes

Scientific name : Amphiprioninae

Anemone fishes belong to the Pomacentridae family, but some peculiarity in their look and behaviour deserve an highlight. Compared with the other damsel fishes, the main differences are in the shape of the fins, all enlarged and rounded, including the tail, and in the colour. The background colour can be pink, orange, red, brown or black, always with white longitudinal lines or vertical bands. Anemone fishes live in obligate symbiosis with few species of sea anemones.
This is one of the best known examples of mutualistic symbiosis. The anemone, with its stinging tentacles, protects the fish from predators. Lika all cnidarians it has the nematocysts, that explode when touched, injecting their poison in any aggressor or prey. The reaction is triggered by the contact, and it is inhibited by substances in the mucus coat: two tentacles belonging to the same anemone can get in touch without attacking reciprocally. The anemone fish is immune to the anemone sting, due to its thick mucus layer. Shuffling on the tentacles, its mucus catches the inhibitory substances, and practically the fish mimics a tentacles: the immunity is total.
In turn, the fish protects the anemone against its only predators: few butterfly fish species, cnidarian feeders.
The observation of the fish bringing food to the anemone is an artefact, due to captivity in aquarium, never observed in the wild where the fish is a Plankton feeders, that swallows directly its food and never move large pieces to the anemone.
It is worth to note how, in the co-evolution, the two partners have completely lost the capability to live alone. The fish developed large, round fins, useful for territorial display but of obstacle for fast swimming: it could not escape predation, if not diving into the stinging tentacles. The anemone has lost the capability to withdraw completely into small cracks, and to avoid the butterfly fish attack: it relies completely on its small defender.
Juveniles of other species resemble the anemone fishes, in colour and movements, like the wrasse Coris gaimard, and the sweetlips Plectorhynchus chaetodonoides.
The benthic eggs are stuck on the rock, at the basis of the anemone, and are guarded by the male. It ventilates them waving the fins, through mouthing it transfers antibiotic substances, it protect them agains predation.
After hatching, the larva enters a planktonic life, is transported by the current, and it have to find another anemone to settle.