Crab-eating Frog (Fejervarya cancrivora)

Identification and characteristics

This medium-sized frog typically has a sturdy body, mottled brown or grey coloring that helps it blend with mud and leaf litter, and long hind legs for jumping. It feeds largely on invertebrates and small aquatic animals; its common name refers to observed predation on small crabs and crustaceans in mangrove areas. Reproduction follows the usual amphibian pattern of aquatic eggs and tadpoles, though the larvae show greater tolerance of saline conditions than most frogs.

Range and habitats

Fejervarya cancrivora is native to coastal and lowland areas of southeast Asia, including the Philippines and extending westward in scattered records as far as Orissa in India. Populations have been introduced to islands such as New Guinea and Guam. Typical habitats include mangrove forests, river estuaries, swamps, and man-made wet places such as rice fields and roadside ditches.

Salt tolerance and physiology

One of the species' most notable features is its ability to survive in brackish or intermittently saline water. Unlike most amphibians, the crab-eating frog can tolerate elevated salinity by physiological adjustments that reduce water loss and help regulate body ions. This adaptation allows it to exploit coastal niches that are unsuitable for many other frog species.

Ecology and human interactions

In coastal food webs the crab-eating frog acts as both predator and prey, consuming insects, crustaceans and other small animals while providing food for birds, reptiles and larger mammals. It commonly occupies agricultural wetlands, where it may benefit farmers by eating pests, but it can also be affected by pesticide use, habitat alteration and the drainage of wetlands. Introduced populations have the potential to interact with local fauna.

Conservation and notable facts

• Notable for salt tolerance uncommon among amphibians.
• Widespread where habitat remains, but local declines can occur from wetland loss and pollution.
• Often cited in studies of osmoregulation and ecological adaptation.

For field identification and region-specific information consult local herpetofauna guides and databases referenced at species overview and regional resources listed above.