Nearly all other metazoans are bilaterians — so named because they have bilateral symmetry. Previous studies have shown that the last common ancestor of cnidarians and bilaterians had about 26 ...

Most animals, including humans, have bilateral symmetry, which means our bodies are pretty symmetrical. At least on the outside. On the inside, things are different. "If you look at our insides ...

It was not so terribly long ago; that the original planktonic mix gave birth to some zillion critters with the advantage of ...