Costa Rica takes up just 0.03% of the world's land - imagine the Earth as a giant pizza cut into 3,000 slices, and Costa Rica is one tiny crumb on one slice. Yet about 1 in every 17 species of plant or animal on Earth lives there.
The reason is geography. Costa Rica sits between two oceans (the Pacific and the Caribbean), has tall mountains down the middle, and lies in the tropics where it is warm and wet all year. That gives it many different 'homes' - cloud forests, rainforests, dry forests, beaches, coral reefs, mangroves - all packed close together.
Scientists have so far counted around 500,000 species in Costa Rica: half a million different kinds of living thing. Around 300 of them are mammals. About 900 are birds. Over 200,000 are insects, and many more are still being discovered every year.
Costa Rica works hard to look after this wildlife. About a quarter of the country is set aside as national parks or protected reserves. That is one of the highest shares of any country in the world.