Crab-eating Frog

Fascinating facts about the Crab-eating Frog

• 144 modern amphibians can tolerate a splash of seawater, and the crab-eating frog is possibly the only extant marine amphibian, surviving brief immersion in sea water.
• When the tide rises to a salinity of 2.8 %, adult crab-eating frogs keep breathing by cranking up urea production and holding onto sodium, staying slightly hyperosmotic while most frogs would soon dehydrate.
• In brackish pools where the water reaches 3.9 % salinity, even the tadpoles of this species can develop, turning a salty nursery into a safe haven that few other amphibians can exploit.

At a glance

About the Crab-eating Frog

The crab-eating frog (Fejervarya cancrivora) is a modest-sized amphibian that prowls the tangled roots and mudflats of mangrove swamps and marshes across south-eastern Asia, from Taiwan and mainland China to Sumatra, the Philippines, and the fringe of Orissa in India. Occasionally it has been introduced beyond its native range, most notably to Guam, likely hitchhiking from Taiwan. Its skin is a muted olive-brown mottled with darker blotches, providing perfect camouflage among the tangled mangrove roots and brackish pools where it spends most of its life. Unlike most frogs, this species can tolerate brief immersions in seawater, a feat it achieves by ramping up urea production and retaining it alongside sodium, keeping its body slightly hyperosmotic. Adults survive in water with salinity up to 2.8 %, while the delicate tadpoles push the limit to 3.9 %, making it one of only 144 modern amphibians known to endure marine conditions and perhaps the sole extant marine amphibian. Its diet shifts with the water’s chemistry: in freshwater fringes the frog snaps up insects, but in brackish habitats it turns to small crustaceans, especially crabs, hence its common name. In Southeast Asia the species is also harvested for its edible legs, a delicacy called swikee in Java, Indonesia, where it is even farmed. This dual life, both as a predator of marine crustaceans and as a culinary staple, highlights the frog’s remarkable adaptability and its subtle yet profound role in the coastal ecosystems it inhabits…

More other animals to discover

Browse Feravox