Why Is the Ocean Salty? Where All That Salt Came From

Ocean waves crashing

Why is the ocean salty? Because water flows toward the ocean carrying dissolved minerals, and the only way out is evaporation — which leaves the minerals behind. Over hundreds of millions of years, that one-way process has concentrated a great deal of salt. Rivers, by contrast, are constantly refreshed by rain and snow, so they … Read more

What Is Bioluminescence? Living Light in the Deep Sea

Fungi growing on a mossy branch

What is bioluminescence? It is light produced by a chemical reaction inside a living organism — no heat, no electricity, no absorbed sunlight. It is genuinely “cold light,” and it is far more common than most people realize: the majority of deep-sea animals make it, and it evolved independently dozens of separate times. The Basic … Read more