We have always been told that amphibians are a very delicate bunch. They are quick to react to changes in environmental conditions, and prefer habitats that are usually wet, lush green and highly productive – tropical forests, freshwater ponds, lakes and swamps, swift torrents and meandering rivers. We don’t find many amphibians in sun-baked deserts or snow-covered mountains. These are places which are either too cold, or too hot for them, and do not have sufficient fresh water. In fact, fresh water is crucial to their survival. Almost all amphibians – Frogs, Toads, Newts and Salamanders require fresh water to live in and breed. Only a handful have managed to evolve ways to cope with its absence.
Most amphibians are also intolerant of salt water. Their delicate, scale-less skins are not good at keeping in moisture or regulating the balance between salt water in the environment and cellular fluids in the body (as is the case with reptiles). This means that most amphibians will die if exposed to marine or brackish water for a considerable period of time. This intolerance to sea water also explains their absence from oceanic islands. However, there are a handful of species that have managed to overcome this handicap. The Crab-Eating Frog of South and Southeast Asia is one such example.
Going by the scientific name of Fejervarya cancrivora, it belongs to the genus Fejervarya and family Dicroglossidae (Fork Tongued Frogs). Unlike most frogs, it can not only stand the presence of brackish water for very long but seems to flourish in saline water habitats – coastal forest, swamps and mangroves. Here, it hunts crustaceans, especially crabs, the prey after which it has been named. The Crab-Eating Frog is able to regulate the osmolarity of its plasma (fluid inside the cells). This prevents cell damage caused by salt water. It is also equally at home in fresh water.
The species, found from southern China’s Guangxi Province in the northeast, across all of peninsular Southeast Asia, to the Malay Archipelago in the southwest, is found on India’s Great Nicobar Islands. It has been introduced to the Pacific island of Guam where it seems to be expanding rapidly. Crab-Eating Frogs are categorized by the IUCN Red List of Threatened Species as being of ‘Least Concern’. They are harvested on a significant scale in countries like Indonesia for their legs, which happen to be a delicacy. But they seem to be doing well despite the culinary demand. Truly one tough critter from Asia!
Image Attribution: The image above, sourced from Wikimedia Commons, is the photograph of a Crab-Eating Frog, uploaded by Bernard Dupont. It was taken in Bako NP, Sarawak, Malaysia.