Biodiversity refers to the variety of life on Earth in all its forms, including plants, animals, ecosystems, and even microorganisms. Although it can be difficult to measure, a country’s biodiversity can be ranked based on the percentage of animal species and plants in comparison to the global total. According to Mongabay, a non-profit conservation and environmental science news platform, these are the top 10 most biodiverse countries on the planet.
Covering over 3.6 million square miles, the United States is the world’s fourth-largest country by area, and its large landmass features a wide variety of ecosystems, from tundras to grasslands, deserts, and forests. These ecosystems can be further divided into ecoregions and biomes — the state of Alaska alone has 15 ecoregions and five biomes. Other states with a wide variety of biomes include California (home to the Redwood Forest, High Sierra, and Mojave Desert) and Arizona (home to Coconino National Forest, the Sonoran Desert, and the Colorado Plateau). More than 200,000 plant and animal species have been documented in the U.S. — including a particularly high number of fish species, thanks to its diversity of marine and freshwater ecosystems.
India, the seventh-largest country in the world, ranks ninth in terms of biodiversity — with an especially high number of reptile species (over 500) and bird species (over 1,300) living within the country’s various ecosystems. The country’s biodiversity also extends to large mammals such as elephants, lions, tigers, and rhinoceroses, as well predatory reptiles such as mugger crocodiles. Many of these larger animals are considered keystone species that help to regulate the animal population and support the country’s rich ecosystems.
Considering that Ecuador’s landmass is smaller than the state of Arizona, it’s particularly impressive that it ranks eighth on this list. In fact, Ecuador has more biodiversity than countries 12 times its size, thanks to its four distinct natural regions — the Pacific coast, the Andes mountains, the Amazon River, and the Galapagos Islands. Both the Amazon region and the Galapagos account for the country’s high number of bird species (more than 1,600) and an impressive number of amphibians (around 580 species).
The island-continent of Australia is home to eight types of land ecosystems, including deserts, tropical and subtropical regions, temperate forests, grasslands, montane lands, tundra, and woodlands. Even more impressive, Australia’s aquatic ecosystems include the Great Barrier Reef, the largest reef system in the world, comprising 10% of the global coral reef ecosystems. Also boosting the country’s biodiversity is the sheer number of reptiles and fish that call Australia home — there are an astounding 869 reptile species, 93% of which are endemic.
Mexico’s ecoregions vary from the Alvarado mangroves in the south and the Chihuahuan Desert — the largest desert in North America — in the north, to pine-oak forests in the West and the Yucatan moist forests in the east. As a result, the country has a mind-boggling array of plants and animals, with an estimated 10% of all of the world's species living in Mexico — including nearly 2,700 species of fish and more than 1,000 species of birds. The country’s three most biodiverse states — Veracruz, Oaxaca, and Chiapas — are home to the Chimalapas Montane Forests, the largest undisturbed cloud forests in Mexico.
Like Mexico, Peru is home to an estimated 10% of the world’s flora and fauna species. The South American nation contains approximately 1,750 species of birds, 2,000 species of fish, 460 species of mammals, and 365 species of reptiles. Peru has six main biomes, including parts of the Amazon rainforest — the world’s largest rainforest — and the Andes mountains — the world’s longest mountain range. The nation is also famous for its biodiverse cloud forests — the one that surrounds Machu Picchu is home to an impressive 18 species of hummingbirds alone.
The world’s third-largest country by area, China encompasses 3.75 million square miles of incredibly varied terrain and a high number of bird, plant, and fish species, in particular. China is home to a range of biomes, from tropical rainforests in Yunnan to the Alashan Plateau, which is located in a portion of the Gobi Desert. The latter is an arid region where snow and sand dunes can converge, and is one of the main sources of dust in the country. It’s also home to several endangered species, such as the Bactrian camel, in addition to mammals such as snow leopards and wild horses.
Colombia’s animal and plant life are some of the most diverse on Earth, but the country particularly shines in the area of bird species — with over 1,800 varieties of birds, Colombia has more than any other country on Earth. It also ranks first for orchid diversity, with 4,270 different species, and is home to a staggering array of butterflies, amphibians, freshwater fish, and plants. From the tropical forests of the Choco and Amazon to the Llanos grasslands and the high mountains of the Andes, Colombia contains over 300 distinct ecosystems, all rich with different forms of life.
Indonesia has much to boast about in the biodiversity department — the archipelago of more than 10,000 islands has more mammal species than any other country. The Southeast Asian country is also home to around 3,000 species of fish, 117 species of sharks, and over 1,700 species of birds. The island of Sumatra is one of the only places in the world where orangutans, rhinos, elephants, bears, and leopards share a habitat. Indonesia also contains a portion of the Coral Triangle, a region that is home to seven marine turtle species and 798 species of coral reef, making it the most diverse coral reserve in the world.
Brazil takes the prize for the most biodiverse country on Earth, with around 120,000 species of invertebrates and 9,000 species of vertebrates. This megadiversity arises from the varied ecosystems throughout the country, which includes the Amazon rainforest; the Mata Atlantica forest; the Pantanal, the world’s largest tropical wetland; and the Cerrado, an expansive tropical savanna. As a result, the country is home to more plant species and amphibian species than any other country on Earth, with an astounding 46,000 species of plants, algae, and fungi, and 1,119 reported amphibious species.