A yellow and brown false water cobra coiled on a rock. — Photo: J. Polák, CC0, via Wikimedia Commons

False Water Cobra

Hydrodynastes gigas

A large South American floodplain snake that flattens its neck like a cobra when threatened.

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About the False Water Cobra

False water cobras are among the larger snakes of South American floodplains. They live in wet, humid areas near streams and rivers in southern Brazil, eastern Bolivia, Paraguay and northern Argentina. They are active by day and can climb, burrow and swim. They eat mostly tadpoles, fish and frogs, plus reptiles, mammals and birds.^[1]

Quick facts

Scientific name: Hydrodynastes gigas^[1]
Diet: Carnivore. Mostly tadpoles, fish and frogs, plus reptiles, mammals and birds.^[1]
Habitat: Wet, humid areas near streams and river floodplains.^[1]
Where it lives: Southern Brazil, eastern Bolivia, Paraguay and northern Argentina.^[1]
Group life: Active by day.^[1]
Babies: Often 2 clutches a year of 14 to 24 eggs.^[1]
Conservation status: Least Concern (IUCN Red List, assessed 2014).^[2]

Fun facts

It flattens its neck like a cobra but isn't one.^[1]
It can climb, burrow and swim.^[1]
Hatchlings are about 15 inches long.^[1]

Vocabulary

floodplain: Flat land next to a river that floods when the river rises.
semiaquatic: Living partly in water and partly on land.
diurnal: Active mainly during the day.
carnivore: An animal that eats mostly meat.
least concern: A conservation label meaning a species is widespread and not at risk of dying out soon.

See it in person

Smithsonian's National ZooWashington, D.C. · Reptile Discovery CenterSee this animal on the zoo's website ↗

These zoos had this animal when we gathered our information, but animals sometimes move. Check the zoo's website or contact the zoo before you visit.

Sources

[1] Smithsonian's National Zoo & Conservation Biology Institute. “False water cobra.” https://nationalzoo.si.edu/animals/false-water-cobra (accessed 2026-10-08)
[2] IUCN Red List of Threatened Species. “Hydrodynastes gigas (False Water Cobra).” https://www.iucnredlist.org/species/15179152/15179161 (accessed 2026-10-08)

Facts last checked 2026-10-08.

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