Saddleback Anemonefish

They shelter in sea anemones

Clownfish form a close partnership with sea anemones. A special mucus on their skin stops the anemone's stinging cells from firing, so they can hide safely among the tentacles. In return, the anemone gains scraps from the clownfish's meals and extra protection from fish that might nibble its tentacles.

Clownfish can change sex

Clownfish live in small social groups with a strict hierarchy. The largest individual is usually female, the second-largest is the breeding male, and the others remain non-breeding males. If the female disappears, the breeding male can transform into a female, while the next male moves up in the hierarchy.