From the tiniest bacteria to the biggest whale, explore life on Earth with Britannica. Find out about our planet's biomes—deserts, grasslands, tropical forests, polar regions, and more—and the plants and animals that call those places home. Learn what the oldest living things on earth are, and how animals are adapting to living alongside humans. Plus, read about Britannica Experts and their work in marine biology, ecology, zoology, and more.