Hydrothermal vents on the seabed spew superheated water, supporting strange communities without any sunlight.

The longer version

Cracks in young crust let seawater seep toward hot rock, where dissolved metals and sulphur compounds make the fluid acidic and extremely hot. Jetting back into freezing water, minerals precipitate and stack chimney walls around the opening.

Bacteria run everything. They oxidise hydrogen sulphide to build sugar without any sunlight, and worms, clams and crustaceans either farm those microbes or host them internally. Residents tolerate pressure, metals and violent temperature gradients. Because vents are scattered and short-lived, larvae must drift long distances to reach the next one before their own field dies. Larvae must therefore grow fast, because food and shelter vanish once the vent cools.

Where this entry sits

Oceans and Sea Life looks at the salt water that covers most of the planet, from crashing waves and tides to the darkest deep-sea trenches. Expect notes on coral, fish, whales, sharks, jellyfish, shells, and the strange creatures that live far below the surface. The full list sits on the Oceans and Sea Life page, where every entry is listed in order.