Ctenophores, also known as comb jellies, are a group of over 200 living species of invertebrate animals with a transparent gelatinous body superficially resembling that of a jellyfish. There is much interest in ctenophore evolution in recent years as their controversial phylogenetic position in the animal tree of life has prompted conflicting hypotheses. While some studies suggest they might represent the earliest branching animals, others suggest a more traditional position as close relatives of jellyfish.