Taxonomic group	Number of U.S. species	Number of species worldwide	Percent of global species in the United States	U.S. ranking worldwide
Freshwater snails	661	4,000	17%	1
Freshwater mussels	292	1,000	29%	1
Crayfishes	322	525	61%	1
Gymnosperms	114	760	15%	2
Mammals	416	4,600	9%	6
Freshwater fishes	799	8,400	10%	7
Tiger beetles	114	2,000	6%	7
Flowering plants	15,320	235,000	7%	>10
Amphibians	231	4,400	5%	12
Reptiles	283	6,600	4%	14
Ferns	556	12,000	5%	>15
Birds	768	9,700	8%	27
Dragonflies/damselflies	456	5,800	8%	?
Butterflies/skippers	620	17,500	4%	?

Source: The Nature Conservancy and Association for Biodiversity Information, Precious Heritage: The Status of Biodiversity in the United States (Oxford University Press, New York, 2000).

Last Updated on 2/9/01