Investigating the evolution and features of regeneration using cnidarians.

The ability to regenerate can greatly vary between animal groups and cell types. Some of the outstanding questions in the field of regeneration include: (1) How has regeneration evolved? and (2) What features underlie differences in regeneration potential between animals? Whether regeneration evolved once and diversified or if it evolved multiple times independently by co-opting similar pathways remains unknown. Current research seeks to identify conserved cellular and molecular features that allow for regeneration. However, comparisons between distantly related regenerating animals have revealed a large amount of diversity. In this perspective, I review discussions on the mechanisms, cell types, and genes underlying regeneration. I propose using Cnidaria as a group in which to investigate the evolution of regeneration. As the sister group to Bilateria with notable regenerative capacity, studies in Cnidaria offer insights into the evolutionary history and conservation of regenerative mechanisms. I then highlight how genome-wide studies, single-cell genomics, multi-omics, and gene editing can be used to identify cell types and unknown features of regeneration. Applying these approaches across organisms will give insight into the cell and molecular features that allow for regeneration competency and may be used to alter an organism's regeneration potential.