As a result of the topography and the seasonal climate the vegetation consist of a many-sided mixture of swamps, grasslands, woodlands and forests (evergreen, semideciduous, gallery, etc.). This mixture has caused an extremely rich fauna. Pantanal is the brazilian ecosystem where concentration of fauna has reached its peak, with a fantastic quantity of individuals of numerous species, particularly aquatic and marsh birds.

In Pantanal and surrounding regions 700 species of birds occur (Dubs 1992). It is one of the most significant breeding grounds for the typical wetland birds such as stork, heron, ibis, and spoonbill that are found in enormous concentrations (Alho et al. 1988). Quite evident are also the 26 psittacidae species including the endangered Hyacinth Macaw (Anodorhynchus hyancinthinus). Other characteristic birds are the Greater Rhea (Rhea americana) , and the Bare-faced Curassow (Crax fasciolata). The large quantity of birds of prey, represented by 45 species, indicates a well balanced ecosystem. (Dubs 1992).

The Pantanal is also one of the last refuges for many threatened neotropical mammal species (Alho et al. 1988) such as Jaguar (Panthera onça), Ocelot (Felis pardalis), Maned Wolf (Chrysocyon brachyurus), Bush Dog (Speothos venaticus), Giant Otter (Pteronura brasiliensis), La Plata Otter (Lutra platensis), Giant Anteater (Myrmecophaga tridactyla), Giant Armadillo (Priodontes maximus), Marsh Deer (Blastocerus dichotomus), and Brazilian Tapir (Tapirus terrestris) (Schaller 1983/Paiva 1984/ IUCN 1990/ Bernardes et al. 1990/ Emmons 1990). The most visible mammal in the Pantanal is the Capybara (Hydrochaeris hydrochaeris) that during the dry season can be observed in herds of up to 30 individuals. Primates are represented by 5 species (Schaller 1983).

Most evident among the Reptiles are the abundant Spetacled Cayman (Caiman crocodilus yacare), the Anaconda (Eunectes notaeus), the Iguana lizard (Iguana iguana) and the endemic Cayman Lizard (Dracaena paraguayensis).

The amphibians are at least 40 different species and fish are remarkably abundant because of the extensive network of lakes, rivers and tributaries, at least 260 species (Wetlands for the Americas 1993) including several species of catfish and piranha (Alho et al. 1988).

Few studies have been made of the invertebrates of Pantanal, although they are numerous, the biology of most of the species is still unknown.