False Water Cobra
Hydrodynastes gigas
A large, aquatic South American colubrid capable of flattening its neck into a cobra-like hood when threatened.
- Venomous?
- Mildly venomous
- Adult length
- 1.5-2.5 m (5-8.2 ft)
- Range
- South America, particularly the Amazon and Paraguay river basins
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Overview
The false water cobra is a large, semi-aquatic snake native to the wetlands and river systems of South America. It gets its name from its dramatic defensive display, in which it flattens its neck into a hood reminiscent of a true cobra, despite being an unrelated colubrid.
It is a rear-fanged species with mild venom, primarily used to subdue amphibian and fish prey, and is not considered a significant threat to humans under normal circumstances.
How to identify it
- Large, heavy body with olive, tan, or brown background color
- Dark blotches or speckling across the back
- Can flatten neck into a hood-like display when threatened
- Round pupils and a broad head
- Smooth to slightly keeled scales
Habitat & range
Found in marshes, flooded grasslands, rivers, and wetlands throughout the Amazon and Paraguay-Paraná river basins of South America. Strongly associated with water.
Behavior, diet & reproduction
Active during the day, an accomplished swimmer that hunts in and around water. Feeds on fish, amphibians, and other small vertebrates. Lays eggs. Known for dramatic hooding and hissing displays when threatened, though bites are rarely medically significant.
Frequently asked questions
Is the false water cobra a true cobra?
No, it is an unrelated colubrid that mimics a cobra's hooding display.
Is it dangerous to humans?
It is mildly venomous via rear fangs, and while a bite can cause local effects, it is not considered a major threat.
Why does it flatten its neck?
As a defensive bluff display to appear larger and more intimidating, similar to a true cobra's hood.
Where is it found?
Wetlands and rivers of the Amazon and Paraguay-Paraná basins in South America.
False Water Cobra guides
In-depth guides for identifying and understanding False Water Cobra.
False Water Cobra identified by the community
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