Hydrodynastes gigas is a New World species of large, rear-fanged, dipsadidae snake endemic to South America. It is commonly and alternatively known as the false water cobra and the Brazilian smooth snake. The false water cobra is so named because when the snake is threatened it "hoods" as a true cobra (Naja species) does. Unlike a true cobra, though, it does not rear up, but remains in a horizontal position. No subspecies are currently recognized as being valid.

Diurnal

Carnivore

Piscivores

Semiaquatic

Appearance

The False water cobra is a rear-fanged venomous colubrid snake native to South America. The background color of a mature snake is an olive green or brown, with dark spots and bands covering much of its body. The background coloring and banding generally become darker towards the end tail. This coloring gives the False water cobra effective camouflage in its natural rainforest environment. The ventral scales are yellow or brown, spotted with dark flecks that make three dotted lines that appear to merge towards the tail. Hatchling and juveniles are much darker in coloration and do not have the typical dark eyes of the adults. They more resemble a garter or water snake than their mature counterparts. Males in this species are typically much smaller than females.

Distribution

Geography

Continents

South America

Countries

Bolivia, Brazil, Paraguay, Argentina

WWF Biomes

Flooded grasslands and savannas , Tropical moist forests

False water cobras are found from eastern Bolivia to southern Brazil, and in Paraguay and Argentina. They generally live in wet, humid areas, and marshlands, typically within the tropical rainforests that are common within their range. However, these snakes may also occur in dryer areas, although this is not their preferred habitat.

Biome

Wetlands

Climate zones

Tropical

Habits and Lifestyle

False water cobras are solitary diurnal creatures. They are very active and inquisitive snakes, which will spend much of the day climbing, burrowing, and even swimming. Their temperaments can vary considerably between specimens; some are very docile and reluctant to bite, whilst others are very defensive and even aggressive or intimidating. False water cobras that are bred in captivity can become quite tame and trusting and many exhibit a high level of intelligence.

Group name

den, nest, pit, bed, knot

Lifestyle

Semiaquatic, Predator, Precocial, Burrowing,

Seasonal behavior

Not a migrant

Venom

The posterior maxillary teeth of H. gigas are enlarged, and the Duvernoy's gland produces a secretion with high proteolytic activity. Besides the ability of this large and powerful snake to inflict mechanical trauma, numerous cases of local envenomation and perhaps hypersensitivity have occurred, most of which have gone unreported. Prolonged, chewing bites may result in painful (sometimes extensive and persistent) swelling, as well as bruising. Nevertheless, the species is regularly kept as a pet, becoming increasingly popular in recent years.

Manning et al. (1999) described a case in which an 18-year-old male pet-store employee was bitten on the wrist by a specimen that hung on for 1.5 minutes. Some mild swelling resulted, but after nine hours, the victim claimed to have experienced three bouts of muscle paralysis, during which he fell and was unable to move or speak, but a medical examination did not produce any unusual results. The symptoms described possibly were the result of anxiety. The liquid venom yield ranges from 0-50 microliters and the solid venom yield is 1.3 mg.

Fun Facts for Kids

The False water cobra is often referred to more simply as either a "falsy" or "falsie" or a "FWC", which is an abbreviation of the common name "false water cobra".
In South America, this snake is sometimes referred to as boipevassu. Additional South American common names include mboi-peba, ñacaniná, surucucu-do-pantanal, vibora ladradora (barking snake), and yacanina.
The False water cobra is so named because of its ability to flatten its neck, similar to a cobra as a defensive reaction to make it look larger and more intimidating. Unlike the true cobra, though, the False water cobra stays in a horizontal position when it hoods, rather than rearing into a vertical position. It can flatten not only its neck but also lower down the body, which is not possible for a true cobra.
The preference of wet land as a habitat for these snakes contributes to their common name of false "water" cobras.
The False water cobra has large eyes with circular pupils, which allows good daytime vision.
It is suggested female False water cobras are brown ventrally, whilst males are yellow. Females are also suggested to have lighter bands and markings on their bodies. However, this is not an effective way of judging the sex of the False water cobra, as coloring usually differs slightly between all individuals.

False Water Cobra

Appearance

Photos with False Water Cobra