a, Adult M. leidyi (approximately 10 cm long). b, Close view of comb rows. c, Aboral view of cydippid stage. d. One-celled fertilized embryo. e–h, Early cleavage stages. i, Gastrula stage. j–m, Later development of M. leidyi embryo. Panels j–m show oral side down. Embryos are approximately 200 microns. See SOM S1 for a more detailed description of the ctenophore body plan. Panel ‘a’ courtesy of Bruno Vellutini.