All clownfish are born male. Groups of clownfish have a dominant female. When she dies, the dominant male changes gender, and all the remaining males move up the social ladder.

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Everything’s Illuminated: 6 Bioluminescent Organisms

Light-producing, or bioluminescent, organisms occur across the spectrum of life—get it, spectrum? There are blinking bacteria, flaming fungus, shimmering squid, and flashing fish. (Interestingly, fish are the only bioluminescent vertebrates and there are no plants that produce light.) Nearly all of