Why do clownfish live in sea anemones?
Quick answer
Clownfish and sea anemones live together in a partnership called mutualism, a kind of symbiosis where both partners benefit. The anemone’s stinging tentacles protect the clownfish from predators. In return, the clownfish chases away fish that eat anemones, cleans it and provides nutrients from its waste.
What each partner gets
| Clownfish gets | Anemone gets |
|---|---|
| A safe home among stinging tentacles | Protection from butterflyfish and other anemone-eaters |
| Scraps of the anemone’s food | Nutrients from the clownfish’s waste |
| A protected place to lay eggs | Better water flow as the fish swims and fans its tentacles |
Studies suggest anemones hosting clownfish grow faster and survive better.
Why don’t clownfish get stung?
A clownfish is covered in a special layer of mucus. Scientists think it either lacks the chemicals that trigger the anemone’s stinging cells or mimics the anemone’s own coating. When a clownfish moves into a new anemone, it often goes through a careful “acclimation dance,” touching the tentacles briefly over hours. Learn how the stings work in how jellyfish sting, since anemones use the same cells.
Types of symbiosis
| Type | Who benefits | Example |
|---|---|---|
| Mutualism | Both | Clownfish and anemone; bees and flowers |
| Commensalism | One benefits, the other is unaffected | Barnacles on a whale |
| Parasitism | One benefits, the other is harmed | Ticks on a dog |
They all start as males
Clownfish are born male. Each anemone holds a group led by one large female and a breeding male, with smaller males below. If the female dies, the breeding male turns into a female, and the next-largest male takes his place. This is called sequential hermaphroditism.
Few anemones qualify
There are about 30 species of clownfish but only 10 of the more than 1,000 sea anemone species host them. Both live mainly on coral reefs in the Indian and Pacific Oceans.
The Finding Nemo effect
After the 2003 film, demand for pet clownfish soared. Today, most clownfish sold in the aquarium trade are bred in captivity, easing pressure on wild reefs.
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