Species 101

Pennsylvania is an ecological crossroads, housing many southern species at the northern extent of their range, and many northern species at the southern extent of their range.  Nearly 17,000 species have been documented in the state, with many more still undiscovered.


Although most people first think of vertebrates such as mammals, birds, fish, amphibians and reptiles when thinking about Pennsylvania’s animals, these groups only make up a small percentage of the total animal species in the state.  Less well known, although much more abundant, are the 12,000+ species of invertebrates including mussels, snails, insects, spiders and other invertebrates.


The Pennsylvania flora includes 3006 species of vascular plants. About two-thirds are considered native species, while the remaining third have been introduced to Pennsylvania through the actions of humans. 443 of these native plants are considered threatened or endangered in the state and 107 are presumed to be extirpated.  A surprising number of nonvascular plants, including nearly 460 species of moss and 150 liverworts, have been identified within the state.

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