In Viet Nam, there is a frog that looks exactly like a lump of moss. Its name is Theloderma corticale, commonly called the Vietnamese mossy frog. The frog lives on damp rock walls and inside rainforest caves that makes it barely seen.
Its skin texture plays the main role in the visual camouflage. Green, brown, and black colors cover the back area to copy real plant leaves. Tiny bumps spread across the skin that makes the frog blend completely with its surroundings.
Built Like a Lump of Moss
Color shades on the body of the Vietnamese mossy frog match green moss species found in northern Vietnam. Its wet skin traps tiny water drops from the humid forest air that gives the frog a surface texture similar to dew on real plants.
Dark markings cover the frog's back in irregular blotches. It matches the natural color variation on wet rocks.
Expanded toe discs on the frog's feet function as suction pads on steep, wet rock walls. The structures allow the frog to cling to damp stone surfaces without sliding down.
Flaps of skin along the sides of the mossy frog lie flat against the rock face when the animal sits still. This physical structure reduces the space between the frog's body and the stone surface.
Pigment cells in the frog's skin change shade based on environmental moisture and light levels. The skin tone shifts between dark green and brown as the frog moves between wet stones and dry plant surfaces.
Staying Still to Hide from Threats
When facing a threat, the mossy frog folds its front legs under its head and pulls its back legs inward. Such movement creates a compact round shape.
The frog closes its eyes during its motionless posture. Skin folds cover the shiny eye surfaces.
Predators of the Vietnamese mossy frog include tree snakes, nocturnal birds, and large freshwater crabs. Camouflage protects the frog from those animals. The frog jumps into nearby water only if direct physical contact occurs.
When it comes to hunting, the Vietnamese mossy frog waits in position until insects enter striking range. Its rapid tongue movements capture the prey.
Life in Humid Limestone Caves
Limestone caves and rocky cliffs in northern Viet Nam give mossy frogs a cool home all year round. Cold water pools near the cave entrance keep the air humid. Such conditions enable the frogs to breathe through their skin.
Mossy frogs only come out at night. About an hour after complete darkness, the frogs crawl out of deep rock cracks to hunt for insects along wet stone walls near running streams.
Breeding also takes place inside these dark rock shelters. Female mossy frogs look for small water pockets hidden beneath stone overhangs, then attach their eggs to dry rock or wooden surfaces near the water.
A thick gelatin layer keeps the egg clusters from drying out in the cave air. After about two weeks, the eggs hatch and the young tadpoles drop straight into the water pool below.
Vietnamese mossy frog tadpoles have dark brown bodies with strong tails designed for swimming in gentle currents. They spend three to five months feeding on organic decay at the bottom of the pool before transforming into young frogs and climbing out onto the cave walls.
