Chickens aren't the brightest creatures in the animal world, but the mother hen knows to protect her eggs and keep them warm. Many species of snakes also care for their young. Amazingly, scientists have learnt that even some plants have been designed with "motherly" instincts.

Ref: Science News, 7/23/05, pp. 59-60, Susan Milius, "Mommy Greenest." Photo: Galls on the head of Plantago lanceolata. Auchenmade (PD):