Total Number of Species Estimated in the World

Over seven million species of plants and animals live on planet earth, according to the best estimates made by biologists.

If you add in the world's species that aren't plants or animals, such as lichens, mushrooms and bacteria, the total number of species leaps much higher. Tallying the estimates of all living things brings the number to 11.3 million species currently on earth.

Among the world's major groups of plants and animals, the most numerous by far are insects, totalling five million species. The rest of the invertebrate species (animals without backbones) add up to another 1.75 million animals. Besides insects, invertebrate animals include worms, centipedes and spiders. Many sea animals also belong to invertebrates, such as shellfish and crabs, sponges, coral, jellyfish and sea anemones.

The world's species encompass nearly four hundred thousand plants. Most plant species are flowering plants, classified as angiosperms.

Least numerous are the vertebrate animals (mammals, birds, reptiles, amphibians and fish) which number eighty thousand. Of these, mammals account for the fewest species, totalling just 5,500.

Estimates of the total number of living plant and animal species on earth.
Category Species Totals
Vertebrate Animals
Mammals 5,500
Birds 10,000
Reptiles 10,000
Amphibians 15,000
Fishes 40,000
Total Vertebrates 80,500
Invertebrate Animals
Insects 5,000,000
Arachnids 600,000
Molluscs 200,000
Crustaceans 150,000
Echinoderms 14,000
Others 791,830
Total Invertebrates 6,755,830
Flowering plants (angiosperms) 352,000
Conifers (gymnosperms) 1,050
Ferns and horsetails 15,000
Mosses 22,750
Total Plants 390,800

About the Numbers

Scientists are fairly certain of how many mammals, birds and coniferous plants in the world, as they have discovered and described nearly all of the species for these groups. The other species estimates listed here are informed guesses, as only a fraction of all species have been formally identified and recorded. Thousands of species of fish, flowers and others still remain undiscovered by science.

No reliable estimate exists of how many species exist of plant algae, the green and red algae. So the total number of plant species given here doesn't include those species. Estimates of plant algae species range from 40 thousand to 140 thousand.

Categories of Invertebrate Animals

  • Arachnids are spiders, mites and scorpions
  • Molluscs are shellfish, snails and squid
  • Crustaceans are crabs, shrimp and lobsters
  • Echinoderms includes starfish, sea urchins and sea cucumbers
  • Others includes worms, centipedes, sponges and jellyfish

Arthur D Chapman. 2009. Numbers of Living Species in Australia and the World. 2nd edition. Australian Government, Department of the Environment, Water, Heritage and the Arts. Canberra, Australia.

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