The Bigger Half

The spine that names it sits below the eye, one on each cheek, and it is the reason nothing else shares this anemone. The fish is the maroon clownfish of the Indo-Pacific, and it is among the most territorial of its family. Divers who put a hand too close come away scratched.

Every anemone of this kind holds one female and one much smaller male, and the female is the larger by a wide margin. She was born male. Anemonefish begin life that way, and the dominant fish of a group changes sex to take the top place when it falls vacant.

The tentacles it lives among would sting any other fish. A coat of mucus, built up by touching the anemone a little more each day, lets it sleep inside them.

This one turned in the tentacles to face the camera, which is what they do. Bangka, north Sulawesi.