Butterflies in your stomach? Not an issue for nearly 8000 species of fishes

The gastric stomach is a hallmark of vertebrate evolution, yet is missing in nearly 25% of living fish species and some mammals. New work by Kato et al. shows how a cassette of genes relating to acid production, pepsins, cell adhesion, and developmental control are repeatedly lost in animals that have also lost their stomachs. The gastric stomach is a hallmark of vertebrate evolution, yet is missing in nearly 25% of living fish species and some mammals. New work by Kato et al. shows how a cassette of genes relating to acid production, pepsins, cell adhesion, and developmental control are repeatedly lost in animals that have also lost their stomachs.