Coral reefs cover less than 1% of the ocean floor but support 25% of all marine species.

Certain fish clean parasites off larger fish.

The Mediterranean Sea loses more water to evaporation than it gains from rivers, maintained by inflow from the Atlantic.

The ocean contains structures larger than mountain ranges.

Certain fish live in symbiotic relationships with other species.

Certain fish can inflate their bodies to appear larger.

The Arctic Ocean may be ice-free in summer within decades, creating new shipping routes and accelerating warming.

Many deep-sea fish have transparent or nearly invisible bodies.

Dolphins surf ocean waves purely for fun — one of the clearest signs of play behavior in animals.