The symbiotic bond between anemonefish and giant sea anemones is one of the most celebrated stories in nature. It has been going on in the oceans for at least 12 million years and is a behavior with which most divers are familiar. Or are we? As we watch and learn more about it, we realize this is no simple story, but a page-turner packed with complex characters, plot twists, love and war!

First, there are more than two in this relationship. Anemones have a threeway symbiosis with anemonefish and the microscopic algae that live in their tissue. Anemonefish benefit from the stinging tentacles, which provide a safe place to live. Short-tentacled anemones offer less protection, but they typically have stronger stings to compensate. In exchange, anemones benefit from a great supply of nutrients and oxygen brought in by the algae, and are protected as the fish chase away anemone-eating species.

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Only a few anemones can host; out of 1,000 species, the relationship occurs in just 10 types. And there are 28 species of anemonefish; some species, like the spinecheek anemonefish, only live in one type of anemone (the bubble tip), while Clark’s anemonefish live in all 10.

Scientists have known of this symbiosis for more than 150 years, but we still don’t fully understand how anemonefish avoid the stings. We know they are not naturally immune and need to acclimatize to be protected. During this period, they rub themselves on the tentacles.The mystery is whether they cover themselves with the anemone’s mucus or their own mucus changes to hinder the stings’effect. I’ve photographed anemonefish rubbing the sides of a tentacle across their eggs, presumably to cover them in mucus so they are not stung.

The stinging anemone may provide a safe refuge, but anemonefish society is far from peaceful. They live in a strict hierarchy enforced by matriarchal aggression. Like many reef fish, anemonefish change sex during their lives. The largest fish in any group is the female, the next is male and all other fish are immature. Aggression is used to remind each fish of its place. The female bullies everyone, while the male harasses the immature fish. The smallest fish spend so much of their time avoiding bullying that they can struggle to feed enough to grow. Divers often mistake smaller anemonefish for the children, but they are unlikely to be related;as anemonefish eggs hatch, they drift in the plankton and mostly settle into a different anemone on a distant reef.

Aggression is triggered by their prominent white bars. Anemonefish can definitely count, and maximum attack is reserved for those with the same patterns.This is why different anemonefish species living on the same reef have different numbers of bars. I’ve noticed some enjoy attacking the bright blue glowing O-rings on my camera system! Younger anemonefish often have less contrasting bars or a different pattern from adults.And other species that shelter in anemones, like domino damselfish and cardinalfish, avoid vertical bars in their patterns.

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Pay attention to these behaviors.While just about every underwater photographer has snapped anemonefish,you can elevate your results by learning about these natural mannerisms.

Everything changes in the anemone when the female dies. Released from her reign, the testis of one of the larger males stop functioning and his/her ovaries become active. The largest of the immature fish will take over the role of male, and all the fish move one place up the queue. It’s a controlled revolution. In Disney’s Finding Nemo, the behavior of Nemo’s father shifts, too, when the mother dies. He becomes braver and more protective, although in nature, he would become a she and more domineering!