Animal
Vietnamese mossy frog
This frog looks just like a clump of green moss. When it sits still, it is almost impossible to spot!
The Vietnamese mossy frog is a tree frog from the forests of Vietnam, southern China and Laos. Its green skin, black spots and little bumps and spines make it look like a clump of moss. It hides in water-filled holes and rock crevices, often with only its eyes showing, and it eats large insects.
Theloderma corticale (family Rhacophoridae) is a cryptically patterned, semi-aquatic tree frog of primary subtropical and tropical forest in Viet Nam, southern China (including Hainan) and central eastern Lao PDR, recorded at 500 to 1,320 m. The IUCN SSC Amphibian Specialist Group listed it as Least Concern (assessed 15 August 2022, published 2022), with a decreasing trend from forest clearing and collection for the international pet trade.
Photo: H. Zell, CC BY-SA 3.0, via Wikimedia Commons
Meet the Vietnamese mossy frog
This frog is green with black spots.
Its skin is covered in little bumps.
It looks like a clump of moss!
The Vietnamese mossy frog has a green body with black spots, and its skin is covered in bumps called tubercles and small spines. Put together, they make it look like a clump of moss. When it sits still, it is almost impossible to see.
It grows up to about 7 to 8 centimeters long. Males tend to be smaller and thinner than females.
Smithsonian's National Zoo: a green body with black spots, visible tubercles and spines give the frog the look of a clump of moss; when motionless it is almost impossible to spot. Adults reach about 7 to 8 cm (3.5 in), males smaller and thinner than females; males have a pronounced breeding callus at the base of the inner finger. The IUCN uses the English name Tonkin bug-eyed frog and notes that Theloderma kwangsiense was synonymised with T. corticale by Hou et al. (2017), which widened the species' known range into China.
Quick facts
- Group
- Amphibian
- Length
- up to 0.08 m
Wet forests, caves and cliffs
This frog lives in forests far above the sea.
It likes rocky streams and mossy caves.
Vietnamese mossy frogs live in northern and central Vietnam, in southern China, including the island of Hainan, and just across the border in Laos. They are found in forests about 500 to 1,320 meters above sea level, sometimes near steep, rocky cliffs.
They shelter in tree holes filled with water and in wet moss. They also live in flooded caves and on the banks of rocky mountain streams.
IUCN: primary subtropical and tropical forest, sometimes associated with steep rocky cliffs in Viet Nam (Orlov 1997); usually sheltering in water-filled tree holes or wet moss (Hou et al. 2017); recorded at 500 to 1,320 m in northern and central Viet Nam, Guangdong, Guangxi and Hainan in China, and central eastern Lao PDR (Brakels et al. 2021). Smithsonian's National Zoo: flooded caves and the banks of rocky mountain streams in northern Viet Nam's limestone and evergreen-forest country; semi-aquatic, hiding in water under rocks and floating plants.
Continent
Its habitat
Where can you find this animal?
- Lives here naturally · Countries and seas named by a scientific source
- Sightings recorded · Records of wild sightings (GBIF)
Lives here naturally · Countries and seas named by a scientific source
Northern and central Vietnam, southern China (Guangdong, Guangxi and Hainan) and central eastern Laos; China is shaded for those southern provinces only, and the IUCN thinks it may also live in Fujian, Hunan, Yunnan and Zhejiang (IUCN).
Places: Vietnam, China and Laos.
Source: iucn-red-list · checked November 2026
Sightings recorded · Records of wild sightings (GBIF)
Counts of GBIF records of wild observations (human and machine) and preserved specimens. Records include introduced populations, vagrants, escaped or released animals and misidentifications, so a country with records is not necessarily part of the native range.
Wild sightings have been recorded in Vietnam, China, United States and Laos.
Source: gbif · checked October 2026
Range maps show where scientists say an animal lives, often country by country. An animal may live in only part of a country shown, and sightings records can include animals that wandered far from home.
Crickets and cockroaches
This frog eats big insects.
It catches crickets and cockroaches.
Vietnamese mossy frogs hunt large insects, such as crickets and cockroaches. Hidden in the water with only their eyes showing, they can keep watch on everything around them.
At the Smithsonian's National Zoo in the United States, the zoo's mossy frogs are fed crickets, cockroaches and earthworms.
Smithsonian's National Zoo: hunts large insects such as crickets and cockroaches; sits in water-filled crevices with only the eyes protruding, watching its surroundings. The zoo's captive diet is crickets, cockroaches and earthworms. The IUCN assessment gives no diet details.
Did you know?
Its eggs are laid above the water.
Mossy frogs lay their eggs just above the water in a flooded hole in a rock, out of reach of animals in the water that might eat them. The tadpoles drop in when they hatch.
Eggs placed above the water line in flooded rock cavities, out of reach of aquatic predators (Smithsonian's National Zoo).
A frog that looks like moss
Its bumpy green skin is its hiding trick.
It has sticky pads on its toes.
The mossy frog's bumpy, spotted skin is its camouflage: it makes the frog look like moss. It can even attach itself in a rock crevice and look like a patch of moss there.
It is a tree frog, with sticky pads on its toes for holding on, and it can jump. When it is frightened, it folds itself into a ball and plays dead.
Cryptic colouration and texture (green ground, black spots, tubercles, spines) are the main defence; individuals attach themselves to rock crevices and resemble moss. Adhesive toe pads, jumping ability. When frightened, it folds into a ball and feigns death. Predators include tree-dwelling mammals and snakes (Smithsonian's National Zoo).
Eggs above the water
The mother lays a few eggs just above water.
The tadpoles drop into the water below.
Mossy frogs breed in holes in rocks where water has flooded the floor. A female lays a small clutch of eight to ten eggs just above the water, which keeps them away from animals in the water that might eat them.
The eggs hatch in 7 to 14 days, and the tadpoles drop into the water below. About three months later, they have turned into little frogs.
Breeding in water-filled rock cavities (Orlov 1997, via IUCN); reproduction observed between March and December (Orlov et al. 2006, via IUCN). Smithsonian's National Zoo: clutch of 8 to 10 eggs placed above the water, out of reach of aquatic predators; hatching in 7 to 14 days, the tadpoles dropping into the water below; metamorphosis after about three months; the species has been bred in human care. Lifespan unknown, probably about ten years.
Hard to find
This frog hides very well.
People find it hard to spot, even when it calls.
Mossy frogs spend much of their time hiding in water, under rocks and floating plants, or tucked into tree holes. One team of scientists called the frog rare, but that may be because it spends most of its time in tree holes, where it is hard to find.
The National Zoo says these frogs can 'throw their voices' 3 to 4 meters, which makes them even harder to find by their calls.
Described as abundant at Tam Dao, northern Viet Nam, in the 1990s (Orlov 1997), but as rare by Hou et al. (2017), possibly because it spends most of its time in tree holes and is hard to detect (IUCN). Smithsonian's National Zoo: semi-aquatic, hiding under rocks and floating plants; can 'throw their voices up to 10 to 13 feet (3 to 4 meters)', making them extremely difficult to find in the wild.
Did you know?
This frog hides by looking like moss!
With its green skin, black spots and little bumps and spines, the Vietnamese mossy frog looks like a clump of moss. When it keeps still, it is almost impossible to spot.
Cryptic colouration and tuberculate skin make it almost undetectable when motionless (Smithsonian's National Zoo).
Forests and the pet trade
People cut down the forests where this frog lives.
Some frogs are caught to be sold as pets.
The Vietnamese mossy frog is listed as Least Concern because it lives over a wide area, but its numbers are thought to be going down. Forests in its range are being cleared for farming, and in China logging and dams also harm its home.
It is popular in the international pet trade, and collecting frogs from the wild to sell may also harm it; in China, illegal collecting is one of its threats. It lives in several protected areas, including Phong Nha-Ke Bang National Park in Vietnam, and zoos in Vietnam and Europe keep and breed it.
Least Concern (IUCN SSC Amphibian Specialist Group; Global; assessed 15 August 2022, published 2022; trend decreasing). Threats: land clearing for agriculture across southeast Asia (Sodhi et al. 2009); in China also logging, hydropower dams and illegal collection; possible wild collection for the international pet trade, in which it is in relatively high demand. Known from Tam Dao and Phong Nha-Ke Bang National Parks (Viet Nam), Nakai-Nam Theun National Park (Lao PDR) and Shiwandashan National Nature Reserve (China); captive populations in Vietnamese and European zoos (IUCN). Smithsonian's National Zoo notes it is protected by the Vietnamese government.
IUCN Red List
How is the vietnamese mossy frog doing in the wild?
- Least Concern (this animal)
- Near Threatened
- Vulnerable
- Endangered
- Critically Endangered
- Extinct in the Wild
- Extinct
Least Concern
Not at risk of disappearing from the wild right now.
Amazing facts
-
This frog hides by looking like moss!
With its green skin, black spots and little bumps and spines, the Vietnamese mossy frog looks like a clump of moss. When it keeps still, it is almost impossible to spot.
Cryptic colouration and tuberculate skin make it almost undetectable when motionless (Smithsonian's National Zoo).
-
When it is scared, it curls up into a ball!
A frightened mossy frog folds itself into a ball and plays dead.
Folds into a ball and feigns death when frightened (Smithsonian's National Zoo).
-
Its eggs are laid above the water.
Mossy frogs lay their eggs just above the water in a flooded hole in a rock, out of reach of animals in the water that might eat them. The tadpoles drop in when they hatch.
Eggs placed above the water line in flooded rock cavities, out of reach of aquatic predators (Smithsonian's National Zoo).
-
Its calls are hard to follow.
The National Zoo says mossy frogs can 'throw their voices' 3 to 4 meters, which makes them very hard to find in the wild.
Reported to 'throw their voices' 3 to 4 m (Smithsonian's National Zoo).
Words to know
- camouflage
- colors or patterns that help an animal blend in with what is around it
- tubercle
- a small, rounded bump on the skin
- crevice
- a narrow crack or gap in rock
- semi-aquatic
- living partly in water and partly on land
- clutch
- a group of eggs laid at the same time
- pet trade
- the buying and selling of animals to be kept as pets
Discovery challenge
-
What does this frog look like?
What does the Vietnamese mossy frog's skin make it look like?
What does the cryptic appearance of Theloderma corticale resemble?
- A clump of moss
- A bright red flower
- A smooth gray stone
Show the answer
A clump of moss
A clump of moss!
Its green skin, black spots, bumps and spines make it look like moss.
Green, black-spotted, tuberculate and spiny skin resembling moss (Smithsonian's National Zoo).
-
What does this frog eat?
What does the Vietnamese mossy frog hunt?
What prey does Theloderma corticale take?
- Large insects, such as crickets
- Fruit and leaves
- Fish
Show the answer
Large insects, such as crickets
Big insects!
It hunts large insects, such as crickets and cockroaches.
Large insects such as crickets and cockroaches (Smithsonian's National Zoo).
-
Where are this frog's eggs laid?
Where does a Vietnamese mossy frog lay its eggs?
Where are the eggs of Theloderma corticale deposited?
- Just above the water in a flooded rock hole
- In the sea
- In a nest high in a tree, far from water
Show the answer
Just above the water in a flooded rock hole
Just above the water!
Eggs are laid above the water in a flooded hole in a rock; the tadpoles drop in when they hatch.
Above the water line in water-filled rock cavities (Smithsonian's National Zoo; Orlov 1997, via IUCN).
-
What does this frog do when it is scared?
What does a frightened Vietnamese mossy frog do?
What defensive behaviour does a frightened Theloderma corticale show?
- Folds into a ball and plays dead
- Changes color to bright red
- Puffs up like a balloon and floats away
Show the answer
Folds into a ball and plays dead
It curls up and keeps still!
It folds itself into a ball and plays dead.
Folds into a ball and feigns death (Smithsonian's National Zoo).
Places where you might see it
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Watch
Natural wonder
Phong Nha–Ke Bang National Park
Phong Nha–Ke Bang National Park, in central Vietnam near the border with Laos, protects one of the world's great limestone landscapes. UNESCO says its rocks began forming about 400 million years ago, and more than 220 kilometers of caves and underground rivers have been mapped. One of them, Son Doong, holds the world's largest known cave passage.
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Watch
Country
Vietnam
Vietnam stretches about 1,650 kilometers along the coast of Southeast Asia, with mountains in the west and two great river deltas, the Red River in the north and the Mekong in the south. About 102.3 million people lived there in 2025. Its capital is Hanoi, and its largest city is Ho Chi Minh City.
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Watch
Country
Laos
Laos is a landlocked country in mainland Southeast Asia, covered mostly by forested mountains. The Mekong River runs along its western side, and most people live in villages and grow rice. Its capital, Vientiane, stands on the Mekong.
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Watch
Country
China
China is the largest country in Asia, almost as big as all of Europe. The land steps down from the high, cold Plateau of Tibet in the west to plains and coasts in the east, and about 1.4 billion people live there, along with giant pandas in the mountains of south-central China.
Explore next
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Watch
Natural wonder
Phong Nha–Ke Bang National Park
Phong Nha–Ke Bang National Park, in central Vietnam near the border with Laos, protects one of the world's great limestone landscapes. UNESCO says its rocks began forming about 400 million years ago, and more than 220 kilometers of caves and underground rivers have been mapped. One of them, Son Doong, holds the world's largest known cave passage.
-
Watch
Country
Vietnam
Vietnam stretches about 1,650 kilometers along the coast of Southeast Asia, with mountains in the west and two great river deltas, the Red River in the north and the Mekong in the south. About 102.3 million people lived there in 2025. Its capital is Hanoi, and its largest city is Ho Chi Minh City.
-
Watch
Country
Laos
Laos is a landlocked country in mainland Southeast Asia, covered mostly by forested mountains. The Mekong River runs along its western side, and most people live in villages and grow rice. Its capital, Vientiane, stands on the Mekong.
-
Watch
Country
China
China is the largest country in Asia, almost as big as all of Europe. The land steps down from the high, cold Plateau of Tibet in the west to plains and coasts in the east, and about 1.4 billion people live there, along with giant pandas in the mountains of south-central China.
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American bullfrog
The American bullfrog is the largest true frog in North America. It lives in warm, still ponds and lakes, sits and waits for food to come close, and the males' deep 'jug-o-rum' call carries more than a kilometer. Its tadpoles can take years to turn into frogs.
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American green tree frog
The American green tree frog is a bright green frog of the southeastern United States, often with a pale stripe along each side. It lives in swamps, marshes and plant-filled pond edges, spending much of its life up in plants, and each finger and toe ends in a round, sticky pad. It is busy mostly at night, when males call a loud, nasal 'guank, guank'.
For parents & teachers
What children will learn
- Explain how the Vietnamese mossy frog's skin works as camouflage.
- Locate Vietnam, southern China and Laos on a map of Asia.
- Describe the mossy frog's life cycle, from eggs above water to frog.
- Name threats to the frog and places where it is protected.
Recommended ages: 3 to 17 · About 15 minutes
Talk about it
- Why might looking like moss help a small frog stay safe?
- Why might laying eggs above the water, not in it, help tadpoles survive?
- What questions should a family ask before buying a pet frog?
Try at home or in class
- Hide and seek: make a small frog shape from green and brown paper, add dark spots, and hide it on a mossy or leafy patch. How long does it take someone to find it?
- Bumpy skin: press a crumpled piece of foil against modelling clay to make a bumpy pattern, and compare it with the mossy frog's skin in the photo.
Key vocabulary: camouflage, tubercle, crevice, semi-aquatic, clutch, pet trade
Where these facts come from
- GBIF Backbone Taxonomy and GBIF Occurrence Search , Global Biodiversity Information Facility (CC0 1.0 (backbone); occurrence counts are facts derived from records under CC0, CC BY and CC BY-NC)
- Wikidata , Wikimedia Foundation (CC0 1.0)
- The IUCN Red List of Threatened Species , International Union for Conservation of Nature (IUCN terms of use (no redistribution of Red List data or range maps))
- Theloderma corticale (IUCN SSC Amphibian Specialist Group, assessed 15 August 2022, published 2022) , IUCN Red List of Threatened Species
- Theloderma corticale: taxonomy, justification, range, population, habitat, threats, trade and conservation text , IUCN Red List of Threatened Species
- Theloderma corticale: IUCN Red List global assessment record (IUCN SSC Amphibian Specialist Group 2022), IUCN checklist on GBIF , GBIF
- Vietnamese mossy frog , Smithsonian's National Zoo and Conservation Biology Institute
- File:Theloderma corticale - Karlsruhe Zoo 01.jpg (H. Zell, 19 August 2019) , Wikimedia Commons
- Wikimedia Commons , Wikimedia Foundation (Per file: Public domain, CC0, CC BY or CC BY-SA only (credited on each page))
Checked, not yet human-reviewed. Last updated November 1, 2026. Spotted a mistake? Tell us.