Mutualistic Symbiosis: Clownfish and Sea Anemone

“I can’t live, if living is without you..” A line from the song, Without You, originally sang by Harry Nilson in the 70’s and was revived by Mariah Carey in the 90’s. Such a lovely song, though it sounds disheartening, real-life relationships hold this words true.

Symbiosis describes close interactions between two or more different species. A relationship where two species live together for the benefit of both. Symbiotic relationships can be obligate or facultative. There are species who lives together by choice; facultative symbiosis, while there are those that can’t survive without the other; obligate symbiosis. The latter gives us that literal phrase, “I can’t live, if living is without you..”

Four main types of symbiotic relationships are mutualism, commensalism, parasitism, and competition. Mutualistic symbiosis is the most common interaction in nature. Many organisms are involved in this kind of symbiotic relationship. This occurs when both species benefit from the interaction. We see this with Thresher Sharks and it’s cleaner fish, the pilot fish. Pollinators, such as bees and birds, receive nectar from plants while transporting pollen that the plants need for fertilization. And much more…

But of course, the extraordinary Clownfish and it’s apparently risky host, the Sea Anemone, shares this mutualistic symbiosis as well. This strange but inseparable relationship is interestingly wonderful.

Clownfish: A Fancy Creature

Family name: Pomacentridae
Order name: Perciformes
Common name: Clownfish / Anemonefish
Scientific name: Amphiprion ocellaris

Two clown fish from the ocellaris species of clown fish (Amphiprion ocellaris) closely related to the Orange Clown fish Amphiprion percula) often live in association with the sea anemone Heteractis magnifica. Scuba diving & underwater photography trip to Liberty’s Apo Island resort near Dumaguete; Dauin, Oriental Negros Province, Philippines.

There are about 30 different species of anemonefish or clownfish. Overall yellow, vivid orange or a reddish or blackish in color, and may show white bars or patches around their body. Clownfish typically grows between 5 and 13 cm, the largest can reach a length of 18 centimeters, while the smallest barely achieve 10 cm. Fins are rounded more than pointed and feature a single nostril on either side of their snouts.

Sea Anemone: Innocently Beautiful Yet Dangerous

Phylum name: Cnidaria
Classification: Anthozoa
Sub-classification: Hexacorallia
Scientific / Order name: Actiniaria

There are over a thousand different species of sea anemones all over the oceans of the world. They come in just about any color and looks like a beautiful flower. Size ranges mostly from 1.8 to 3 cm in diameter, the smallest is about 4 mm, while the largest can reach a diameter of more than 6 feet. Most sea anemones anchor itself to the sea floor but there are few species who are pelagic.

I can’t live, if living is without you. Literally.

Clownfish are pretty small and are poor swimmers making them an easy prey to large and hungry predators in the wild. Therefore, having a host is vital for their survival. The anemone provides the clownfish a safe nesting place for their eggs, and a shelter against possible predators.

Being called a killer fish trap, sea anemone’s tentacles have stinging cells, nematocysts, that release a toxin when prey or predator touches it. They use this to entrap fish and other organisms for food. However, clownfish have a protective chemical coating or mucus on their skin that keeps them from being stung.

When choosing a host, the clownfish intermittently touches the anemone for a few hours, this enables them to adapt and modify it’s protective coating to conform to the host’s particular poison. Thereafter, the anemone considers the clownfish as one of its own.

Sea anemone, on the other hand, needs protection from butterfly fish, who feeds on their tentacles. Clownfish serves as marine bodyguards that drive the butterfly fish and other predators away. Eats the parasites that would harm the anemone, provides energy through their ammonium excretion, and help circulate oxygen-rich water to the anemone by its fanning movement among the tentacles. At least one species of anemone cannot live without resident clownfish.

Such good partnership among two diverse organism offers a fascinating lesson in life and work…


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