1.

A tune that gets stuck in your head is called an 'earworm'.

2.

The male praying mantis cannot copulate while it's head is attached to it's body. The female initiates sex by ripping the male's head off.

3.

In 2005, a baby was born with a conjoined head that had no body. The head could even blink and smile.

4.

When snakes are born with two heads, they fight each other for food.

5.

The praying mantis is the only insect that can rotate its head 360 degrees.