If you've ever seen a dolphin swim, you may have wondered why they undulate their bodies up and down when swimming, instead of side to side as fishes do. Though they have a fishlike body, cetaceans (a ...

Vertebrates are animals with a backbone. You are a vertebrate. And now, a researcher has formally described the world’s tiniest vertebrate — a new species of frog.

As far back as the 19th century it was apparent to some biologists that a simple, repeated pattern underlay the differing body structures of animals. It could be seen in the segmented bodies of worms, ...