clownfish
A small orange-and-white reef fish that lives in sea anemones.
A clownfish is a small, brightly colored ocean fish that lives among the stinging tentacles of sea anemones. These fish have developed a remarkable partnership with their anemone hosts: the clownfish's body is covered in special mucus that protects it from the anemone's sting, allowing it to swim safely through tentacles that would paralyze other fish. In return, the clownfish chases away fish that might eat the anemone and even brings it food scraps.
Clownfish get their name from their bold orange and white stripes, which make them look a bit like tiny underwater circus performers. The most famous clownfish is probably Nemo from the movie Finding Nemo, which shows how clownfish live in anemones on coral reefs in warm tropical waters.
Here's something fascinating: all clownfish are born male, and they live in small family groups within their anemone home. If the one female in the group dies, the largest male will transform into a female to take her place. This unusual ability helps clownfish communities survive in their small territories on the reef.