Red Sea clownfish

The Red Sea has its own anemonefish, a two-banded species that lives nowhere else. Each anemone holds one breeding pair and a queue of smaller males, and the fish coat themselves in mucus that stops the anemone's stinging cells from firing.

They are absurdly brave for a fish eight centimetres long. A pair will charge a diver's mask repeatedly to drive it away from the anemone, which is why every reef guide has been headbutted by one.