Biology Now, 2e

Insects

1,000,000

Plants

310,100

Arachnids

102,200

Fungi

99,000

Mollusks

85,000

Crustaceans

47,000

Fish

31,200

Roundworms

25,000

Flatworms

20,000

Millipedes and centipedes

16,100

Birds

10,000

Jellyfish and polyps

9,800

Reptiles

8,700

Amphibians

6,500

Sponges

6,000

Mammals

5,500

Segmented worms

16,800

There are an estimated 8.74 million eukaryotic species on Earth, yet

we are familiar with only a fraction of those. Scientists estimate

that 86% of land species and 91% of aquatic species have not been

discovered. Of the known species, insects top the chart with an

estimated 1 million different species.

Assessment available in