A damselfish cultivates underwater gardens of an algal species that researchers haven't found growing on its own.
The special alga could be the fishy version of people's domesticated crops, says Hiroki Hata of Kyoto University in Japan. Growth tests of the alga, surveys of its distribution, and genetic analyses support that idea, he and Makoto Kato say in an upcoming Biology Letters.
People have been slow to get the hang of farming. Starting millions of years before the rise of human agriculture, certain ants, termites, and ambrosia beetles grew fungi for food. Today, they sow, fertilize, and weed their crops. A few of these spineless cultivators even employ bacteria to make pesticides.