Content area
Full Text
Hydrobiologia (2008) 595:587591 DOI 10.1007/s10750-007-9030-4
FRESHWATER ANIMAL DIVERSITY ASSESSMENT
Global diversity of crocodiles (Crocodilia, Reptilia) in freshwater
Samuel Martin
Springer Science+Business Media B.V. 2007
Abstract Living crocodilians include the 24 species of alligators, caimans, crocodiles and gharials. These large semi-aquatic ambush predators are ubiquitous in freshwater ecosystems throughout the worlds tropics and warm temperate regions. Extant crocodilian diversity is low, but the group has a rich fossil record in every continental deposit. Most populations suffered from over-hunting and habitat loss during the twentieth century and even though some species remain critically endangered others are real success stories in conservation biology and have become important economic resources.
Keywords Crocodile Alligator
Gharial Archosauria
Introduction
The living crocodilians belong to the order Crocodylia which is now represented by three families: the Crocodylidae, the Alligatoridae and the Gavialidae (Brochu, 2003). The 24 species of the group are all-amphibious and share morphological, anatomical,
and physiological features, which make them more adapted to water than to land (Lang, 1976).
They all live in tropical and subtropical areas in various aquatic habitats (forest streams, rivers, marshes, swamps, elbow lakes, etc.) and can be considered as the largest fresh water dwellers. They can occasionally adapt to salty waters (mangroves or estuaries) (Dunson, 1982; Mazzotti & Dunson, 1984). They are nocturnal carnivorous opportunistic predators, whose diet depends on their developmental stage, species and potential prey diversity (Magnusson et al., 1987). All crocodilian species may be considered as totally water dependent since they can only mate in water. Crocodilians appear to be very important for freshwater ecosystems as they maintain, during the dry season waterholes that are used as reservoir for many arthropods, crustacean, shes and amphibians (Gans, 1989; Kushlan, 1974).
Species/generic diversity
With only 24 living species, the order Crocodylia is the smallest taxonomic group of the class Reptilia. The three families, Crocodylidae, Alligatoridae and Gavialidae are quite homogeneous taxa as they contain between two and four genera.
The highest level of species diversity is to be found in the genus Crocodylus which gathers 13 species, whereas other genera only display one or two species.
Guest editors: E. V. Balian, C. Lvque, H. Segers &K. MartensFreshwater Animal Diversity Assessment
S. Martin (&)
La Ferme aux Crocodiles, Pierrelatte 26700, France e-mail: [email protected]
123
588 Hydrobiologia...