Morphological character reconstruction in Cnidaria. Reconstruction of key morphological characters in Cnidaria based on the phylogenetic hypothesis based on mitogenomic data. (1) symmetry: b = bilaterial, r = radial or biradial; (2) gain (+) and loss (−) of free-swimming medusoid stage (many hydrozoans have secondarily lost the medusoid phase); (3) velum (lost in some leptothecate hydrozoans); (4) strobilation; (5) gastric filaments; (6) ephyrae; (7) radial canal (scored uncertain in Cubozoa); (8) circular canal; (9) square symmetry of horizontal cross section; (10) gastrodermal muscles: e = in bunches of ectodermal origin, g = in bunches of gastrodermal origin, n = not organized in bunches. Morphological characters are taken from Marques and Collins (2004) and Cartwright and Nawrocki (2010) studies. Drawings were provided by Matthew Palen.