Symbiotic Green Algae

Unicellular green algae form symbioses with diverse organisms. For example, different kinds of green algae can live with fungi, forming lichens. Green algae also live inside of ciliates, foraminifera, cnidarians (e.g., hydra, sea anemones), and even with vertebrates. The ability of algae to form symbiosis has evolved multiple times, as illustrated by the phylogenetic tree below.