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.
| 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 | |
| Plants | ||
| Flowering plants (angiosperms) | 352,000 | |
| Conifers (gymnosperms) | 1,050 | |
| Ferns and horsetails | 15,000 | |
| Mosses | 22,750 | |
| Total Plants | 390,800 | |
| TOTAL SPECIES | 7,227,130 |
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
Reference
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.