Urutu Snake

Bothrops alternatus

Last updated: April 19, 2022
Verified by: AZ Animals Staff
Image Credit Mark_Kostich/Shutterstock.com

The female Urutu snake grows longer and heavier than males of the same species

Urutu Snake Scientific Classification

Kingdom
Animalia
Phylum
Chordata
Class
Reptilia
Order
Squamata
Family
Serpentes
Genus
Bothrops
Scientific Name
Bothrops alternatus

Read our Complete Guide to Classification of Animals.

Urutu Snake Conservation Status

Urutu Snake Locations

Urutu Snake Locations

Urutu Snake Facts

Prey
Opossum, amphibians, and small rodents
Name Of Young
Snakelets or neonates
Fun Fact
The female Urutu snake grows longer and heavier than males of the same species
Estimated Population Size
Unknown
Biggest Threat
Global warming and habitat destruction
Most Distinctive Feature
Triangle-shaped head
Distinctive Feature
Chocolate brown pattern with white or cream borders
Temperament
Aggressive
Litter Size
3 to 12 neonates
Habitat
Rainforests and humid regions of Brazil, Argentina, Paraguay, and Uruguay
Predators
Humans capture them for the pet trade
Diet
Carnivore
Common Name
Yarará grande, víbora de la cruz, urutu, wutu, crossed pit viper
Number Of Species
1

Urutu Snake Physical Characteristics

Color
  • Brown
  • Yellow
  • White
  • Tan
  • Cream
  • Chocolate
  • Olive-Grey
Lifespan
15.2 years
Length
31 to 67 inches
Venomous
Yes
Aggression
High

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Urutu snakes are aggressive pit vipers capable of causing severe tissue damage and even death to humans with their venomous bite.

Urutu snakes, also called yarará grande, wutu, and crossed pit vipers, are native to rainforests and humid regions of Brazil, Argentina, Paraguay, and Uruguay. They are highly venomous pit vipers in the Bothrops genus, also called lanceheads.

Being pit vipers, these snakes have heat-sensing pit organs on both sides of their head, between their eyes and nostrils. These organs help them sense opossums, small rodents, amphibians, and other prey in their wetland habitats. When attacking, the aggressive snakes pierce the animal’s flesh with their large fangs and inject a tissue-damaging venom. Although the Urutu’s venom is potentially deadly, only about 2% of bitten humans die from the bite. Most bitten people experience tissue death in the area of the bite, as well as extensive bleeding. Many bite victims must undergo amputations of limbs after these attacks.

It is because the Urutu has such dangerous bites that they are often hunted or trapped by farmers in their native geographies. Most of this hunting and trapping is to prevent permanent injury, severe symptoms of the bite, or death to livestock or humans.

5 Amazing Facts

  1. Larger females: The female Urutu snake grows longer and heavier than males of the same species
  2. Humid living conditions: Urutus do not live in dry conditions and instead make their home in wetlands, tropical forests, marshes, swamps and alongside major rivers or streams
  3. Member of the Viperidae family: The Urutu shares a family with more than 200 species of venomous fanged snakes, including rattlesnakes
  4. Triangle-shaped head: Being a pit viper, the Urutu has a telltale triangular head due to the placement of its venom glands
  5. Damaging venom: The Urutu’s venom causes immediate tissue damage in the body, also inhibiting blood clotting and sometimes leading to death

Where to Find Urutu Snakes

The Urutu snake is found in countries of South America, specifically Brazil, Paraguay, Uruguay and Argentina. Its habitats include tropical forests, semitropical forests and temperate deciduous forests within marshes, swamps, riverbanks, floodplains and other areas with high humidity. The snakes are often found on sugarcane plantations of South America, as well as in open fields, rocky regions, grasslands, tropical savannas and on the banks of rivers and streams. Urutu are not found on dry lands or in arid regions.

Although these snakes can be deadly because of their venomous bite and aggressive nature, some people choose to keep them as pets. They are sometimes available on the exotic pet market. States and local regions each have their own laws about owning these animals. Despite being legally able to own one in some areas, having a pet Urutu brings risks. One woman from Ohio was killed by her pet Urutu pit viper in 2004. When the bites are not deadly, they cause severe symptoms and even permanent physical injuries.

Scientific Name

The Urutu snake of South America has dozens of other names that vary according to geographic region and dialects. The most common names are Urutu, wutu and crossed pit viper. In Argentina, it is called yarará grande and víbora de la cruz. Brazilians call the snake boicoatiara, coatiara, cruzeira, jararaca de agosto, jararaca rabo-de-porco and urutu, as well as other variations of these terms. Paraguans call the Urutu by several names, including yarará acácusú, mbói-kwatiara and mbói-cuatiá. Uruguans refer to the venomous pit viper as yarará, víbora de la cruz and crucera.

The snake’s scientific name is Bothrops alternatus. This official name of Bothrops comes from the Greek term bothros, meaning “pit”, and ops, meaning “eye” or “face,” in reference to the pit viper’s heat-sensitive facial organs. That term is coupled with the Latin alternatus, meaning “alternating” and referring to the snake’s color pattern. The snake is in the pit viper family Viperidae and class Reptilia.

Population & Conservation Status

According to the International Union for the Conservation of Nature (IUCN) Red List of Threatened Species as of 2014, the Urutu snake’s conservation status is of “least concern.” This means the snake’s population is stable, widespread and under no major threats. The animal’s most common threat is from sugarcane farmers hunting and trapping the snakes that encroach on their lands or pose risk to livestock or humans.

Because they are not widely hunted and have little commercial value outside of the exotic pet trade, the snakes are able to thrive within their native habitats. Of course, global warming and habitat destruction pose risk to the snake populations for the future.

Reproduction

These snakes give birth to from 3 to 12 live young. Baby snakes that are born live instead of hatching from eggs are called neonates. Urutu neonates are capable of making a venomous strike as soon as they are born.

Appearance & Description

Urutu snake colors vary widely. They can range from dark chocolate and almost black blotched pattern colors to tan, olive green and gray. The most common description of the snake’s coloration is that of a yellow, tan or off-white body with dark brown kidney-shaped pattern from neck to tail. The head is mostly dark brown color with tan to white markings creating a well-defined pattern.

Urutu body length is usually between 31 inches and 47 inches. But there are documented reports of the snakes measuring as long as 67 inches in the wild. Females are much longer and heavier than males.

Other ways to identify an Urutu snake include the animal’s head. Like all venomous pit vipers, the snake’s head is triangular in shape. This shape relates to placement of the venom glands on each side of the head, making the head extend dramatically outward from the neck. The snakes also have two long fangs that inject venom into their prey, although these are not readily visible unless the snake is biting. They locate their prey using visible heat sensitive organs on each side of the face, between each eye and the snout.

How to identify Urutu snakes:

  • Typically 31 inches to 47 inches long, but can measure as long as 67 inches
  • Yellow, tan or off-white body and belly color
  • Dark brown, black, tan, gray or olive green dorsal pattern from head to tail tip
  • Blotchy pattern kidney shapes defined by yellow, tan or off-white borders
  • Triangular head indicating placement of venom glands on each side of the head at the neck
  • Heat-sensing pits on each side of the head between each eye and the snout
Urutu snake displays vivid pattern
Urutu Snakes have distinctive chocolate brown patterns bordered by white or cream

Fabio Maffei/Shutterstock.com

Urutu Snake Venom: How Dangerous Are They?

Urutu snakes are usually deadly to humans in only 2 of every 100 bites. Their venom generally causes a range of extreme symptoms like major tissue damage at the region of the bite which can lead to gangrene and even the need for limb amputation. All injured victims experience pain and swelling, with most also experiencing delayed blood clotting by 12 minutes or longer.

Effects of a venomous Urutu snake bite include:

  • Severe tissue damage
  • Delayed blood clotting by 12 minutes or longer
  • Local pain and swelling
  • Bleeding from the gums
  • Local blistering
  • Tissue death
  • Severe scarring
  • Death in about 2% of cases

A deadly dose of Urutu snake venom is typically between 2.2mg of venom per kilogram of body weight to 4.1mg of venom per kilogram of body weight. Treatment for the snake’s bite requires use of specific antivenin. If you are bitten by an Urutu snake, one of the most important facts about this animal is that it is critical that you seek immediate emergency medical attention.

Urutu Snake Behavior & Humans

Urutu snakes are highly venomous and aggressive. They do not seek out humans as prey but do aggressively defend themselves when they perceive a threat. Because the snakes live in mostly wild regions of South America, farmers are usually the only humans crossing paths with these pit vipers. Farmers are also responsible for many of the snakes’ deaths each year, through hunting and trapping to ensure the safety of people and livestock near the reptiles’ habitat. When humans keep Urutu snakes as exotic pets, there is greater potential for human injury and death from the highly venomous bite.

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Urutu Snake FAQs (Frequently Asked Questions) 

Are Urutu snakes venomous?

Urutu snakes are highly venomous pit vipers. Their bite leads to severe tissue damage and a wide range of other symptoms. About 2% of humans bitten by the snakes die from the venom. In most cases, antivenin provided quickly by emergency medical services can reduce the damage caused by the venom. Some injured victims must undergo amputations of the bitten limb because of the extent of tissue necrosis.

How do Urutu snakes hunt?

Urutu snakes are pit vipers. They use the heat-sensing organs on each side of their head, between each eye and the snout, to detect their prey. This prey is typically opossums, small rodents like mice and guinea pigs, or amphibians like frogs. They move quietly along the ground, find the prey and attack quickly and aggressively. The snake then injects its deadly venom into the animal to kill it for immediate feeding.

Are Urutu snakes aggressive?

Urutu snakes are aggressive to prey and other animals crossing their path. In South America where these snakes are native, they are considered a major threat for snakebite. Their aggression is usually defensive when they perceive a threat. They also sometimes attack unsuspecting or non-threatening animals when seeking food. A sleeping pet owner in Ohio was bitten by her Urutu pit viper in 2004 when the reptile escaped from its cage. The pet owner died from her injury.

Where do Urutu snakes live?

Urutu snakes are native to the South American countries of Argentina, Paraguay, Uruguay, and Brazil. The animal’s name varies by region and dialect. It dwells mostly in tropical forests, semitropical forests, and temperate deciduous forests within marshes, swamps, riverbanks, floodplains, and other areas with high humidity. It is also frequently found on sugarcane plantations.

What do Urutu snakes eat?

Urutu snakes usually eat opossums and small rodents. They will also eat amphibians like frogs. The small rodents that frequently make a meal for these reptiles include mice, rats, and guinea pigs that the snake hunts using its heat-sensing organs on each side of its head.

Is a urutu snake bite deadly?

One of the most important facts about the urutu snake is that it has a deadly bite. But only about 2% of bitten humans die from the snake’s venom today. Most seek immediate medical care and antivenin treatment. As a result of an Urutu snake bite, people experience severe tissue damage, blood clotting problems, pain, swelling, bleeding gums, and other immediate symptoms.

Where are urutu snakes found?

Urutu snakes are found in humid regions of Argentina, Brazil, Paraguay and Uruguay. The highly venomous reptile is often detected on sugar plantations and in the wetlands of these countries. Because the snake does not migrate, it remains within its native geographies except when transported on the exotic pet market.

What other names does the urutu snake go by?

There are dozens of names for the Urutu snake according to region and dialect. The most common names include yarará grande, wutu, and crossed pit vipers. In Argentina, it is also called víbora de la cruz. Brazilians call the snake boicoatiara, coatiara, cruzeira, jararaca de agosto and jararaca rabo-de-porco, as well as other variations of these terms. Paraguans call the Urutu by several names, including yarará acácusú, mbói-kwatiara and mbói-cuatiá. Uruguans refer to the venomous pit viper as yarará, víbora de la cruz and crucera.

Sources
  1. Wikipedia, Available here: https://en.wikipedia.org/wiki/Bothrops_alternatus
  2. Reptile Database, Available here: https://reptile-database.reptarium.cz/species?genus=Bothrops&species=alternatus
  3. iNaturalist, Available here: https://www-inaturalist-org.translate.goog/guide_taxa/1486603?_x_tr_sl=pt&_x_tr_tl=en&_x_tr_hl=en&_x_tr_pto=sc
  4. Reptile Fact, Available here: https://www.reptilefact.com/urutu.html
  5. Jungle Dragon, Available here: https://www.jungledragon.com/specie/9936/urutu.html
  6. Department of Ecology University of São Paulo, Available here: http://eco.ib.usp.br/labvert/alternatusPredation.pdf
  7. Wikipedia, Available here: https://en.wikipedia.org/wiki/Bothrops_alternatus
  8. Reptile Database, Available here: https://reptile-database.reptarium.cz/species?genus=Bothrops&species=alternatus
  9. iNaturalist, Available here: https://www-inaturalist-org.translate.goog/guide_taxa/1486603?_x_tr_sl=pt&_x_tr_tl=en&_x_tr_hl=en&_x_tr_pto=sc
  10. Reptile Fact, Available here: https://www.reptilefact.com/urutu.html
  11. Jungle Dragon, Available here: https://www.jungledragon.com/specie/9936/urutu.html
  12. Department of Ecology University of São Paulo, Available here: http://eco.ib.usp.br/labvert/alternatusPredation.pdf
  13. Research Gate, Available here: https://www.researchgate.net/publication/236897128_Bothrops_alternatus_Urutu_Predation
  14. Agencia Fapesp, Available here: https://agencia.fapesp.br/a-protein-from-urutu-snake-venom-could-be-beneficial-to-the-heart/18088/
  15. Fauna Paraguay, Available here: http://www.faunaparaguay.com/bothropsalternatus.html
  16. EOL, Available here: https://eol.org/pages/52233800
  17. IUCN Red List (1970) Snakelets or neonates

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