Evolution of the marine animal forest: EvoDevo of corals, sea anemones, and jellyfishes

Abstract

Cnidarians are the sister group of Bilaterians, so they are in a unique position to provide essential clues about the evolution of developmental pathways in animals. It is surprising that with only 10,000 described species, they come in so many different forms, shapes, sizes, and colors. Reef corals, that certainly look as a rich marine forest, are the clearest example of this phenotypic plasticity. Cnidarians are an ancient phylum that together with Porifera, Placozoa, and Ctenophora stand at the base of the animal kingdom tree. Cnidarians share with Bilaterians the main molecular toolkit genes used for patterning cells and tissues and build the basic animal body plan. Plasticity in the Wnt, Fgf, Bmp, and Hox molecular pathways is a key factor to understand such morphological evolution, as these are the main players in the patterning of the anteroposterior and the dorsoventral axes and therefore fundamental to ultimately shape the reef seascape. We intend to provide a link between the diversification of the toolkit versatile genetic pathways to the myriad of shapes of corals, sea anemones, and jellyfishes. The objective is the understanding of how all that morphological richness is produced transforming the molecular repertory. Coral reef species variability makes you appreciate the diversity of forms of marine organisms and makes you understand why conservation efforts must be a priority if we want to preserve this special case of biodiversity.