It’s International Day for Biological Diversity, a day to celebrate the variety of life on Earth in all its forms, from bacteria, plants, and animals to entire ecosystems like coral reefs and rainforests. All living things within each ecosystem are interconnected, and we rely on healthy ecosystems for our water, food, medicines, clothes, energy, and shelter. But many species are threatened with extinction and ecosystems are being destroyed, which mean Earth’s rich biodiversity is in decline.