Anemones and Clownfish Symbiosis

There is an interesting relationship between anemones and clownfish. If you have had the joy of snorkeling in undeveloped areas, you may have had the unpleasant experience of bumping into one of some 800 species of anemones. Their tentacles contain toxin-filled capsules called nematocysts that fire stingers at anything that touches them. I can tell you from personal experience that it is extremely painful.

I finally learned to stay away from the anemones and just look at them. I saw that some fish died when they touched the tentacles. Interestingly, other fish, shrimp, and crabs lived among the tentacles and seemed unaffected by their stings. The very colorful clownfish lives right in the middle of the tentacles and appears to be immune to the anemone’s poison. Spider crabs and shrimp live at the base of the anemones. Crabs carry around baby anemones using them as defensive weapons. Even a baby anemone could deliver a nasty sting to my finger.

The clownfish seem to have the greatest skill for avoiding the anemone stings. When the clownfish is threatened, it will dive into the anemone tentacles for protection. The anemones eat algae remains that float in the water, and also small fish, sea urchins, shrimp, and some crabs. The clownfish benefit the anemones by removing parasites from them while the anemones provide the clownfish protection from predators.

So how do the clownfish avoid being stung by the anemones? They secrete a very thick mucus that does not trigger a response from the nematocysts. The clownfish can be all over the anemones and not get stung. Scientists are studying the mucus of the clownfish because it has potential uses for humans. The mucus is an anticoagulant and disrupts the gill function in sharks, making it an excellent shark repellent. Some researchers believe that the clownfish gets the mucus from the anemones, but other research studies show that the clownfish has a gene that produces the mucus. Research continues in the study of anemones and clownfish.

Science has a lot of data without a clear answer to how anemones and clownfish live in such a well-orchestrated symbiotic relationship. It would appear that the design of this symbiosis, like many others, is a product of God’s design and is not naturally acquired.

— John N. Clayton © 2020

Data from National Wildlife magazine April/May 2020 and their websites.