Snakes don't have eyelids. They have a protective membrane on each eye, called brille, which allows them to sleep with their eyes open. ¹⁾.

Genetic studies in recent years have indicated that snakes are not as closely related to monitor lizards and mosasaurs as believed. However, there is more evidence linking mosasaurs to snakes than mosasaurs to varanids. ²⁾.

Living snakes are found on every continent on Earth except for Antarctica. ³⁾.