Hippos are some of the earth’s largest land animals. Their name derives from Greek when they were called “river horses,” ...

Dolphins’ open-mouth behaviors during play are like smiles, a study claims. Whether smiles or not, the gestures seem to be important for how dolphins communicate ...

What they can eat is limited to and dependent on how big the Burmese python’s mouth opening can stretch. Researchers call this the snake’s gape. More: Python challenge: Why state recommends ...