Dolphins can recognize themselves in mirrors.

Penguins have excellent underwater vision.

Steve Irwin died after being pierced by a stingray barb.

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

The Pacific Ocean is larger than all of Earth's landmasses combined.

Some deep-sea fish have expandable stomachs to consume rare prey.

Bioluminescence is common among deep-sea organisms.

In 1796, Edward Jenner developed the world's first vaccine by using cowpox material to induce immunity against smallpox, a breakthrough that led to the disease's global eradication.

The immortal jellyfish is the only known animal capable of reverting to its juvenile form repeatedly.