The fauna and flora of West Bengal possess the combined characteristics of the Himalayan and sub Himalayan Gangetic plain. Biodiversity is shaped by the biotic and abiotic components of its environment and this state has a rich assemblage of diverse habitats and vegetation designated with the help of eight different forest types. Diversity is further reflected in different types of ecosystem available here like mountain ecosystem of the north, forest ecosystem (semi-evergreen, deciduous, dry, moist and tidal varities) extending over the major part of the state, freshwater ecosystem (rivers, streams, wetlands and to some extent estuaries), semiarid ecosystem in the western part, mangrove ecosystem in the south and coastal marine ecosystem along the shoreline.

      These diverse ecosystems has resulted in rich faunal diversity of the state and consists of 10,013 species out of a total of 89,451 species of animals present in our country, thus representing 11.19% of our countries fauna. The floral diversity of the state is also enriched by 4,622 species out of a total of 44,594 floral species in India, and 10.36% of our countries flora.

       Maximum species diversity in fauna has been observed in Arthropoda Among other groups Protozoa (969), Bird (649), Mollusca (280), Nematoda (283), Platyhelminthes (248),Mammals (188), Annelida (187), Rotifera (146), Reptilia (146), Amphibia (50) are with wide number of species.

        District wise analysis show that highest number of fauna is present in Kolkata (4256), and then in Darjeeling (4166); Jalpaiguri (1563); South 24 Pgs (1516); North 24 Pgs (943) etc.

        Total area of district and faunal diversity is negatively correlated (r = -0.29567); while the total forest covered and faunal diversity is positively correlated (r = 0.17849).

        Floral diversity in number of species in the state is maximum in Dicot (1994). Other groups in respect of dominance are Monocot (493), Algae (873), Fungi (539), Lichen (329), Pteridophyte (330), Bryophyta (43) and Gymnosperm (21).

         Darjeeling (2439) is well ahead in floral diversity followed by Medinipur (871); Jalpaiguri (789) and Murshidabad (725).

         Floral diversity and total forest cover has a positive correlation (r = 0.1089). Floral diversity and total area of district shows a negative correlation ( r = -0.12494).

         The faunal and floral diversity shows a positive correlation (r = 0.6771).

        Biodiversity enrich districts are Darjeeling followed by Kolkata, South 24 Pgs, Medinipur, North 24 Pgs, Nadia, Malda, Murshidabad etc.

        A positive correlation (r = 0.1707) is seen between biodiversity and forest cover, where as the correlation with area covered is negative (r = -0.2664), same with the total population of district (r = -0.20552).