Martindale is one of the founders of the school of evolutionary developmental biology. He is renowned for his technically challenging cell-lineage studies. Martindale’s papers have appeared in Science and Nature. His research focuses on the major problems of animal body plan evolution, and his lab played a major role in changing the perceptions of the relationship of bilaterians to other animals. One of Martindale’s most important contributions has been to demonstrate that cnidarians, which are radially symmetrical, are much closer to bilaterians than previously believed.