Clownfish with Anemone

One of the more fascinating aspects of coral reef life is the formation of partnerships between two entirely different crea­tures in order to increase chances for survival. “Commensalism” occurs where a partnership benefits only one of the partners but no harm is done to the other partner.  “Mutualism” is a partner­ship which results in benefit to both partners.  A striking example of a partnership is the clownfish and the sea anemone. 

The clownfish, sometimes called anemonefish, is part of the Damsel­fish family.  In the Red Sea, clownfish are golden colored with two white (sometimes blue) vertical stripes on each side of the pectoral fin and are called the two-bar anemonefish.  In other oceans, clownfish can be red or pink with one or more white or colorful vertical stripes or even have wavy bands or stripes.  Clownfish are ap­proximately 3 to 5 inches in length.

Clownfishes inhabit the tentacles of the large sea anemones.  An anemone is an invertebrate animal, not a plant.  It has a body or column which spreads itself over the strata of a reef.  Emerging from the body of the anemone are many tentacles.  The tip of each tentacle contains a stinging nematocyst.  When the anemone is stimulated by prey coming in contact, the tentacles grasp,  enfold the prey and inject paralyzing nematocysts into the prey.

Large sea anemones can look like the nap of a thick carpet, resemble translucent or colored “fingers” waving in the water, or seem like translucent long-stemmed mush­rooms. The tentacles and column appear in beautiful diverse colors. 

The clownfish (and some other Damselfishes) is immune from the sting of the sea anemone tentacles.  The clownfish is covered with a certain mucus which prevents the anemone from reacting to the clownfish as prey.  Clownfish inhabit the ten­tacles of the sea anemone as a refuge from predators because other fish will not enter among anemone tentacles.  The sea anemone can benefit from bits of food dropped by the clownfish.  It is also thought that clownfish benefit sea anemone by cleaning them of parasites and algae, as well as by swimming among the ten­tacles and creat­ing currents of water which benefit the respira­t­ion of the sea anemone. 

The photograph of this tomato clownfish and anemone was taken in 1991 at the New Georgia Island barrier reef, Solomon Islands, with a Canon F-1, 50mm macro lens and Fuji Velvia ISO 50 film.