The tongue of a blue whale is so large that 50 people could stand on it.

Penguins have excellent underwater vision.

The Caspian Sea is the world's largest inland body of water and is classified as a lake despite its salt water.

The giant amphipod thrives in extreme ocean depths.

Vaccination campaigns have eliminated several diseases in many regions.

The Arctic fox changes fur color with the seasons.

The Mariana Trench is so deep that Mount Everest could be placed inside it and still be covered by over a mile of water.

The Earth's poles experience extreme seasonal variations in sunlight.

Male seahorses carry and give birth to their young.