The San Esteban spiny-tailed iguana (Ctenosaura hemilopha conspicuosa) is an excellent example of the endemic island reptiles of the islands in the Gulf of California. Many kinds of organisms, including plants, reptiles and mammals were stranded on the islands as Baja separated from the mainland, or managed to colonize these bits of land by accident during the ensuing millions of years. Living in isolation in the low diversity island ecosystems for long periods, these populations diverged genetically from those on the mainland, slowly becoming new species or sub-species, found nowhere else on earth.
Some developed unique characteristics such as the gigantism of the San Esteban giant chuckwalla or the rattlelessness of the Santa Catalina rattleless rattlesnake (Crotalus catalinensis). Conservation of these islands is of critical importance because such isolated habitats are invaluable to biologists as laboratories of evolution and because they are nice places for early morning walks.
