Fig. 1.

Bacteria-induced metamorphosis is widespread among animal taxa. (A) Many species from diverse taxa possess a biphasic lifestyle in which they undergo metamorphosis between larval and adult phases of life (blue). Nearly all of these taxa possess representative species that metamorphose in response to bacteria (yellow). (B) Hydroides developmental life cycle. RNA was sequenced from five stages of Hydroides development: precompetent larvae, competent larvae, larvae induced to metamorphose by the addition of MACs for 5 min and 30 min, and adult animals. A circular GFP-labeled MAC array is depicted in green. (C) The number of homologous genes identified between the Hydroides genome and the genomes of other model animals. The Hydroides (lophotrochozoan) genome is more similar to deuterostome animals (urchins, sea squirts, and humans) than to model ecdysozoan species. Polychaete worm, Capitella teleta; Pacific oyster, Crassostrea gigas; purple sea urchin, Strongylocentrotus purpuratus; zebrafish, Danio rerio; human, Homo sapiens; starlet sea anemone, Nematostella vectensis; transparent sea squirt, Ciona intestinalis; fruit fly, D. melanogaster; nematode, C. elegans.