Fig. 1

Body symmetries on metazoan phylogeny. a Schematic diagram of a bilaterian embryo and three representative cnidarian polyps with different symmetry types. A section of cnidarian polyps (gray dashed line) perpendicular to the oral–aboral axis representing the positional arrangement of gastric pouches. Symmetry planes of these arrangements are represented by gray dotted lines. b Schematic of life cycles for sexual and asexual reproduction (pedal laceration) modes. c External view of D. lineata. Orange-striped patterns orient to the oral–aboral axis in a longitudinal green body column. Scale bar, 2 mm. d Internal view of D. lineata. Horizontal cut of a polyp showing the actinopharynx, siphonoglyph, muscles, and mesenteries. Scale bar, 200 μm. e Asexual reproduction of a few individuals (framed with black dashed lines) by pedal laceration. Scale bar, 1 mm. ap: actinopharynx, gp: gastric pouch, sp: siphonoglyph, mu: muscle, me: mesentery, pr: partition, te: tentacles