Amphibians Active at night

Crab-eating Frog

Fejervarya cancrivora

iNaturalist Wikipedia

The Crab-eating Frog is the ultimate coastal survivor, famously known as the only amphibian that can thrive in the salty waters of mangroves and sea marshes. Watch as this nocturnal hunter prowls the shoreline for its namesake prey.

0 Sightings

0 Habitats

Quick Identification

straighten

Size

Body length typically 5–8 cm (2–3 in) for males, with larger females reaching up to 12 cm (4.7 in); weight ranges from 40–120g (1.4–4.2 oz)

palette

Colors

Mottled olive-brown, grey, or charcoal upper body with dark irregular blotches; pale cream or white belly; dark bars often visible on the legs and lips

visibility

Key Features

Distinct longitudinal skin folds or ridges along the back
Extensive webbing on the hind toes reaching the tips
Pointed snout with a frequent pale stripe running down the spine

When You’ll See Them

schedule

Activity pattern Active at night

brightness_5

Peak hours 7 PM - 3 AM

calendar_month

Season Year-round, with peak activity during the rainy season (monsoon)

restaurant

Diet A generalist carnivore that primarily hunts small crustaceans (especially shore crabs), aquatic insects, beetles, and occasionally small fish or other frogs.

park

Habitat Mangrove swamps, salt marshes, coastal estuaries, and brackish rice fields near the ocean.

public Geographic range

Where Does the Crab-eating Frog Live?

Native to the vibrant coastal ecosystems of Southeast Asia, the Crab-eating Frog's range stretches from the eastern coast of India and southern China through the Malay Peninsula to the many islands of Indonesia and the Philippines. This species is a lowland specialist, almost exclusively found near sea level where land meets the tide. Beyond its native shores, it has also established a successful introduced population on the island of Guam, demonstrating its incredible ability to colonize new tropical coastal environments.

Basemap © OpenStreetMap contributors

10 Countries

4.2M km² Range

Least Concern Conservation

ID Indonesia PH Philippines TH Thailand Vietnam MY Malaysia CN China Taiwan IN India Cambodia Guam

eco

iNaturalist / Verified observation data

View on iNaturalist open_in_new

Explore more Amphibians arrow_forward

Behavior

The Crab-eating Frog is a remarkable biological anomaly, being one of the very few amphibians capable of surviving in brackish and salt water. Unlike most frogs whose skin would lose vital moisture to the salt, this species can increase the urea levels in its blood to balance osmotic pressure. They are predominantly nocturnal, spending their days hiding in crevices, under coastal debris, or in burrows to avoid the tropical sun, emerging at twilight to hunt along the water's edge.

During the breeding season, which often coincides with the onset of the monsoon rains, males gather in brackish pools to call for mates with a series of short, raspy croaks. While they are generally solitary and wary of human presence, they have adapted well to human-altered landscapes, often being found in coastal rice paddies and roadside ditches near the sea. They are skilled swimmers and powerful jumpers, using their strong hind legs to escape into the water or thick mangrove roots when threatened.

photo_camera EverydayEarth exclusive

Camera Tips

To capture the Crab-eating Frog on camera, placement is everything. Focus your camera on the 'intertidal zone' of your backyard or local coastal patch—specifically near brackish ponds, slow-moving drainage ditches, or the edges of mangrove roots. Because these frogs are relatively small, mount your camera very low to the ground, no more than 6 to 10 inches high, and angle it slightly downward to capture the ground-level action. If your camera allows for macro-focusing or has a close-up lens attachment, use it to ensure the frog's skin textures and ridges remain sharp.

Since this species is strictly nocturnal, a camera with high-quality infrared (no-glow) LEDs is essential to avoid startling the animal. Set your PIR (passive infrared) sensor to the highest sensitivity; frogs are cold-blooded and may not always trigger sensors designed for warm-blooded mammals unless they are moving actively. Using a 'Burst Mode' of 3-5 photos or short 15-second video clips is highly recommended to catch the quick, snapping tongue movements when they are feeding on crabs.

If you are trying to attract them to a specific spot for a photo, creating a small 'frog pond' with slightly brackish water and low-wattage solar lights can help. The lights will attract insects and small crabs, which in turn will bring the Crab-eating Frog right into your camera's field of view. Ensure your camera housing is rated for high humidity and salt-spray resistance, as the coastal air can be corrosive to electronic equipment over time. Check your equipment weekly to wipe the lens of salt crust or condensation.

Similar Species

Species that look similar or are commonly confused with Crab-eating Frog.

Rice Field Frog

Smaller in size with less webbing on the hind toes; lacks the high salt tolerance of the Crab-eating Frog.

American Bullfrog

Much larger with a distinct large eardrum (tympanum) and lacks the longitudinal skin folds found on the Crab-eating Frog's back.

Browse all Amphibians arrow_forward

Frequently Asked Questions

Crab-eating Frogs are nocturnal, meaning they are most active after sunset. They typically emerge from their hiding spots around 7 PM and remain active throughout the night, hunting for crustaceans and insects until the early morning hours.

If you live in a coastal area within their range, you can attract them by maintaining a natural shoreline, avoiding heavy pesticides, and providing moist, shaded hiding spots like log piles. A small brackish water feature can also serve as a major draw for both the frogs and their prey.

As their name suggests, they are famous for eating small crabs. However, they are opportunistic hunters and will also consume beetles, grasshoppers, moths, snails, and occasionally other small amphibians found in their mangrove habitats.

Yes, they are quite adaptable. While they prefer mangroves, they are frequently found in suburban coastal developments, rice paddies, and even garden ponds that are close to the sea or have slightly elevated salinity levels.

While similar in shape, the Crab-eating Frog is generally larger and has much more extensive webbing on its hind feet. Additionally, the skin ridges on the back of the Crab-eating Frog are usually more pronounced and longitudinal compared to the Rice Field Frog.

Record Crab-eating Frog at your habitat

Connect a camera to start building your own species record — AI identifies every visitor automatically.

Join free Identify a photo