Comb Jellies, the Gelatinous Branch of the Animal Tree

Around 700 million years ago, a group of organisms resembling little more than glowing, gelatinous blobs split off from the rest of the animals — possibly the earliest branching animal lineage. Their descendants are the ctenophores, commonly known as comb jellies, and nearly 200 species of them live today. The familiar name misleads: comb jellies are not jellyfish. Whatever else they are, they have been on their own branch of the animal tree for an extraordinarily long time.