NEOTENY

Most juvenile animals aren’t simply miniature adults. Rarely is this more obvious than among amphibians – think of a tadpole and a frog. Sometimes, though, youthful characteristics are retained into adulthood. In the axolotl, an aquatic Mexican salamander, adults are essentially sexually mature tadpoles. Neoteny can also be seen in flightless female glow worms, which are much like their larvae. Humans’ large heads may be a neotenous development to make space for our big brains.

The adult axolotl, also known as the ‘Mexican walking fish’ remains much like a tadpole.