Undiscovered Species - How Many Are There Left to Find?

Most of the world's species remain undiscovered by science.

Biologists have described and classified 1.7 million plants and animals as of 2010, less than one-quarter of the total species estimated in the world. Scientists figure there are still over five million species waiting to be found. The table below lists how many undiscovered species exist for each type of plant and animal.

So far, zoologists have reported on nearly all the mammal and bird species currently living on earth. There may be a dozen or so left that as yet are unknown to science.

Most of the fish and reptiles are already identified, but there remain several thousand more left to find. Meanwhile, new techniques in molecular biology are helping scientists identify new amphibian species.

Undiscovered Animals

Where most of the discovery work still needs doing is with invertebrate animals, creatures without backbones. Taxonomists have classified only one-fifth of all invertebrate species.

About four million insects have not yet been examined and named. Another half million spiders and their relatives are still unidentified. Plus hundreds of thousands of aquatic creatures, ranging from snails to sponges, remain mysterious.

Unknown Plants

There are still nearly one-fifth of vascular plants left to discover, not including an unknown number of plant algae species. While scientists have documented nearly all the coniferous plants, these make up a tiny fraction of all plant species. Thousands of the world's flower, fern and moss species are new to science and have yet to be recorded.

How many species still remain undiscovered.
Category Species Totals
Vertebrate Animals
Reptiles 1,300
Amphibians 8,500
Fishes 8,000
Total Vertebrates 17,800
Invertebrate Animals
Insects 4,000,000
Arachnids 500,000
Molluscs 115,000
Crustaceans 103,000
Echinoderms 7,000
Others 700,000
Total Invertebrates 5,425,000
Flowering plants (angiosperms) 71,000
Ferns and horsetails 15,000
Mosses & Liverworts 6,500
Total Plants 80,500

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

Number of New Species Discovered Each Year

Each year scientists record another 18,000 new species of plants and animals. In recent years they added about 70 new reptiles and 400 new fishes annually to the world's databases of species.

Even more discoveries of plants and invertebrates have come forward. Biologists every year document about 2,000 new species of flowering plants and 13,500 new invertebrates.


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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