Y
Species Profile

Yellow Anaconda

Eunectes notaeus

Paraguay-Paraná's stealthy giant
cellistka/Shutterstock.com

Yellow Anaconda Distribution

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At a Glance

Wild Species
Also Known As Beni anaconda, Anaconda amarilla, Sucuri-amarela
Diet Carnivore
Activity Cathemeral+
Lifespan 15 years
Weight 55 lbs
Status Least Concern
Did You Know?

Adult females commonly reach 2.6-3.5 m total length; males often 1.8-2.4 m (Dirksen, 2002).

Scientific Classification

The yellow anaconda (Eunectes notaeus) is a large, semi-aquatic boa native to south-central South America, especially the Paraguay–Paraná basin. It is a nonvenomous constrictor that hunts fish, birds, and mammals in wetlands and seasonally flooded savannas.

Kingdom
Animalia
Phylum
Chordata
Class
Reptilia
Order
Squamata
Family
Boidae
Genus
Eunectes
Species
Eunectes notaeus

Distinguishing Features

  • Yellow-tan body with dark oval blotches
  • Robust, heavy-bodied semi-aquatic boa
  • Eyes and nostrils positioned dorsally
  • Ambush predator using constriction
  • Strong association with marshes and swamps

Physical Measurements

Males and females differ in size

Length
♂ 6 ft 11 in (4 ft 11 in – 8 ft 10 in)
♀ 9 ft 10 in (7 ft 10 in – 15 ft 1 in)
Weight
♂ 15 lbs (7 lbs – 33 lbs)
♀ 55 lbs (33 lbs – 77 lbs)
Tail Length
♀ 12 in (9 in – 1 ft 6 in)
Top Speed
4 mph
swimming

Appearance

Primary Colors
Secondary Colors
Skin Type Smooth scales
Distinctive Features
  • Large semi-aquatic boa from Paraguay-Paraná basin wetlands.
  • Olive-yellow body with bold black oval spots in rows.
  • Dark head markings; eyes and nostrils positioned dorsally.
  • Adults typically 2.0-3.0 m total length; females larger.
  • Robust, muscular body adapted for ambush hunting in water.
  • Nonvenomous constrictor; seizes prey at water's edge.
  • Diet commonly fish, waterbirds, rodents, and small caimans.
  • Activity peaks in flooded seasons; often concealed in vegetation.
  • Compared with green anaconda, generally smaller and more yellow.
  • Reported captive lifespan commonly 20-30 years.

Sexual Dimorphism

Females are typically longer and heavier than males, with a more robust mid-body. Males tend to have relatively longer tails and more prominent cloacal spurs, reflecting mating adaptations.

♂
  • Smaller overall length and mass than adult females.
  • Relatively longer tail, aiding cloacal alignment during mating.
  • More prominent cloacal spurs near vent region.
♀
  • Greater average and maximum body length than males.
  • Broader, heavier trunk; thicker mid-body girth.
  • Often more expansive abdominal area for live-bearing reproduction.

Did You Know?

Adult females commonly reach 2.6-3.5 m total length; males often 1.8-2.4 m (Dirksen, 2002).

Maximum reported total length is about 4.6 m, though most individuals are far shorter (Dirksen, 2002).

It is ovoviviparous (live-bearing); litters recorded from 4 to 82 young, neonates ~55-60 cm (Dirksen, 2002).

Native to south-central South America, especially the Paraguay-Paraná basin: Pantanal, Chaco wetlands, Paraguay, Bolivia, Brazil, Argentina, Uruguay (IUCN).

A semi-aquatic ambush hunter, it commonly takes fish, waterbirds, and small mammals along marsh and flooded-savanna edges (IUCN).

Compared with the green anaconda, it is usually smaller and more strongly patterned with dark blotches on a yellow-olive background (Dirksen, 2002).

Unique Adaptations

  • Dorsally positioned eyes and nostrils let it watch and breathe while most of the body stays submerged.
  • Laterally compressed tail and powerful trunk muscles aid swimming and sudden acceleration in shallow wetlands.
  • Heat-sensing labial pits help detect warm-blooded prey even in darkness or murky water.
  • Bold blotched pattern breaks up its outline among reeds, shadows, and sun-dappled floating plants.
  • Flexible jaws and expandable skin allow swallowing relatively large prey whole after constriction.

Interesting Behaviors

  • Ambushes from shallow water, striking prey at the shoreline and pulling it into cover to constrict.
  • Tracks seasonal flooding, using newly inundated savannas for hunting and retreating as waters recede.
  • Breeding can involve "mating balls," with several males competing and aligning with one receptive female.
  • Often remains motionless with only eyes and nostrils exposed, relying on camouflage in floating vegetation.
  • Basks on banks or mats of plants to warm up, then returns to water for concealment and hunting.

Cultural Significance

Across river and wetland communities of the Paraná-Paraguay region, anacondas symbolize the power of water and hidden wildlife. Today they also feature in Pantanal/Chaco ecotourism and conservation discussions about wetland predators.

Myths & Legends

In Peruvian Amazon tradition, Yacumama ("Mother of Water") is a gigantic serpent that rules rivers, creating dangerous whirlpools; it's often imagined as an enormous anaconda.

Brazilian Amazon folklore tells of Cobra Grande/Boiúna, a colossal river-serpent that can overturn canoes, flood shores, or even become a river itself.

Regional "sucuriju" stories in Brazil and Paraguay describe huge lagoon-dwelling anacondas that guard waterways, seize livestock or boats, and vanish into flooded forests.

Conservation Status

LC Least Concern

Widespread and abundant in the wild.

Population Unknown

Protected Under

  • CITES Appendix II

Life Cycle

Birth 30 newborns
Lifespan 15 years

Lifespan

In the Wild
10–20 years
In Captivity
15–30 years

Reproduction

Mating System Polygynandry
Social Structure Aggregation Group
Breeding Season July-October, late winter to spring
Breeding Pattern Transient
Fertilization Internal Fertilization
Birth Type Internal_fertilization

Yellow anacondas are typically solitary but form temporary breeding aggregations. Multiple males often court and copulate with a single female in a "mating ball," and individuals do not maintain pair bonds; females provide no parental care beyond gestation.

Behavior & Ecology

Social Solitary Group: 1
Activity Cathemeral, Crepuscular
Diet Carnivore fish

Temperament

Secretive
Defensive
Ambush-oriented

Communication

hissing
pheromone trailing
tongue-flick chemoreception
cloacal scent cues
tactile courtship contact
vibration/substrate sensing
body posturing

Habitat

Biomes:
Wetland Freshwater Savanna Tropical Dry Forest
Terrain:
Riverine Plains Muddy
Elevation: Up to 984 ft 3 in

Ecological Role

Wetland mesopredator controlling aquatic and riparian vertebrate populations

prey population control trophic regulation nutrient redistribution

Diet Details

Main Prey:
Fish Water birds Rodents Amphibians Reptiles

Human Interaction

Domestication Status

Wild

Yellow anacondas have never been domesticated. They are periodically captured from wetlands for the skin trade and for zoological collections, and they appear in research and education programs across South America (notably the Paraguay-Paraná basin).

Danger Level

Moderate
  • Nonvenomous bite; deep lacerations
  • Constriction risk to children/pets
  • Defensive strikes when handled
  • Water-side encounters in wetlands
  • Salmonella from contact
  • Max reported ~4.0 m adults

As a Pet

Not Suitable as Pet

Legality: CITES Appendix II; legality varies by country/state permits.

Care Level: Expert Only

Purchase Cost: $200 - $800
Lifetime Cost: $8,000 - $25,000

Economic Value

Uses:
Leather Pet trade Ecotourism Research Conflict Education
Products:
  • skins
  • leather
  • specimens

Relationships

Predators 6

Jaguar
Jaguar Panthera onca
Puma
Puma Puma concolor
Yacaré caiman Caiman yacare
Black caiman Melanosuchus niger
Southern caracara Caracara plancus
Human
Human Homo sapiens

Ecological Equivalents 4

Animals that fill a similar ecological role in their ecosystem

Green anaconda
Green anaconda Eunectes murinus Semi-aquatic ambush constrictor in floodplains, with a similar prey spectrum.
False water cobra
False water cobra Hydrodynastes gigas Wetland snake that hunts fish, amphibians, and birds in South American marshes.
Yacaré caiman Caiman yacare Co-occurs in the Paraguay-Paraná wetlands; an aquatic ambush predator that takes similar prey.
Neotropical otter Lontra longicaudis Riverine predator that consumes fish and waterbirds within the same basins.

Yellow anacondas are generalist carnivores and will eat anything they can overpower with their massive size and strength.

These are large snakes in the boa family that live in South America. While not as well-known as the even bigger green anaconda, these snakes achieve lengths of up to 15 feet long and 80 pounds.

Amazing Facts About Yellow Anacondas

  • Many people keep yellow anacondas as pets and say they’re more “bitey” than other snakes.
  • Females don’t lay eggs, they give birth after the eggs develop inside their mom’s body for 6 months.
  • Yellow anaconda adults have few natural predators, but juveniles are often eaten by bigger carnivores, even adult yellow anacondas have been known to eat them.

Yellow Anacondas: Where Can You Find Them?

The yellow anaconda is endemic to South America in marshlands and swamps of the Paraguay River and its tributaries in Bolivia, Paraguay, western Brazil, northeastern Argentina, and possibly northern Uruguay. It prefers mostly aquatic habitats and avoids dry areas. There may be a population in southern Florida, but it’s unclear whether it’s breeding; these snakes are present in the area thanks to people who illegally release their pet anaconda when it gets too big.

This species spends most of its time in or near the water, actively foraging or waiting to ambush its next meal. The yellow anaconda eats a wide variety of prey animals including mammals, birds, reptiles, amphibians, fish, and eggs. It is capable of taking much larger prey than other Boidae species and bigger snakes can eat larger animals such as capybaras, peccaries, or caimans. There may be some cannibalism, but no one knows how prevalent the behavior is.

While it moves slowly on land, it is quick and agile in the water. Anacondas that live in areas with seasonal flooding and dry periods must stay wet, and they do this by burrowing into the mud. Yellow anacondas usually mate between April and May; the female carries the babies for about 6 months until they are born.

Adult yellow anacondas don’t have many natural predators, but juveniles and the occasional adult may be taken by caimans, jaguars, cougars, and other larger predatory animals.

Scientific Name of the Yellow Anaconda

The yellow anaconda’s scientific name is Eunectes notaeus. Anacondas are part of the Boidae family and cousins to boa constrictors. Eunectes means good swimmer, and notaeus is a Latin synonym for dorsal because its dorsal blotches (on the back) are different than that of the green anaconda.

Yellow anacondas have several names. They’re often called the Paraguayan anaconda; another name, matatoro, is a Spanish term that means bull killer. However, Native American terms include sucuri and yakumama. They’re also called water boas; an accurate term reflecting their preferred habitat and status as boa family members.

Yellow Anaconda Population and Conservation Status

Yellow anacondas are common in their native habitats in Brazil, Bolivia, Paraguay, and northern Argentina. They’re rare in Uruguay, where scientists haven’t fully ascertained whether there’s a breeding population. This snake has a stable population in its home range, and they’re categorized as Least Concern on the IUCN Redlist. In 1997, the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) recommended that the export of their skins be halted, but otherwise, they’re not protected.

Even in areas where people have harvested the species heavily for its skin, their population appears unaffected. This leads researchers to believe that in suitable areas, they achieve a relatively high population density.

The wet, subtropical ecosystem in Florida is prime habitat for this water-loving snake. As a result, released anacondas can become a problem. Florida Fish and Wildlife considers the introduced anacondas invasive and actively captures them to remove them from the environment. They even have a special phone number to call to report a sighting.

Identifying Yellow Anacondas: Appearance and Description

This is a large snake, second only to the green anaconda in weight. The yellow anaconda has a noticeably yellow base color, which can vary between greenish-yellow and brownish-yellow. Over the base color are dark blotches that are typically dark brown to black.

Its head is blunt, like other boa family snakes, and its eyes and nostrils are more towards the top of its head. It has elliptical pupils, and stripes that start right behind its eyes and extend towards the back of its head. Its teeth are curved inwards to move prey into its throat, and it has dozens of razor-sharp teeth.

This species is sexually dimorphic and the females grow much longer and heavier than the males. Females can reach 15 feet long and 80 pounds, while the males typically only reach about 10 feet long and approximately 50 pounds.

Yellow anacondas are cousins of boas and constrict their prey until it stops breathing. They have powerful jaws capable of holding their prey while their muscular body coils around it and squeezes.

Yellow anacondas are huge constrictor snakes.

Pictures and Videos of Yellow Anacondas

Yellow anacondas aren’t great pets and can be aggressive.

Yellow Anaconda

Yellow anaconda closeup

How Dangerous are Yellow Anacondas?

This is a pretty aggressive species, and it is happy to bite if it thinks you’re a threat. Or if it just doesn’t want you near it. In some parts of the U.S., selling them across state lines is illegal, and in Florida, they’re illegal to own without a permit.

The good news is that they’re not venomous, so you’re not likely to die or need medical care from a yellow anaconda bite. However, a larger anaconda that decides you are a threat will bite repeatedly; if you continue to hold it, that anaconda will most likely coil around you and squeeze. If it goes on too long, the animal can easily break human bones.

Yellow Anacondas Behavior and Humans

In the wild, these snakes avoid human contact. They’re relatively shy and don’t want anything to do with people. However, yellow anacondas are highly defensive and will repeatedly bite to make you back off from them. These snakes are large predators with slow metabolisms that allow them to wait weeks and sometimes months between meals, depending on the size.

Yellow anacondas (and anacondas in general) are frequently seen as a threat to human and livestock life. So, locals often kill the larger specimens as a preventive measure. As people encroach further into areas where they live, encounters are more likely to occur, and the anacondas are often the losers.

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Sources

  1. Tropical Conservation Science / Published March 28, 2016 / Accessed April 23, 2022
  2. Yellow Anaconda | IUCN Redlist / Published March 20, 2020 / Accessed April 23, 2022
  3. CITES / Published June 2, 1997 / Accessed April 23, 2022
Gail Baker Nelson

About the Author

Gail Baker Nelson

Gail Baker Nelson is a writer at A-Z Animals where she focuses on reptiles and dogs. Gail has been writing for over a decade and uses her experience training her dogs and keeping toads, lizards, and snakes in her work. A resident of Texas, Gail loves working with her three dogs and caring for her cat, and pet ball python.
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Yellow Anaconda FAQs (Frequently Asked Questions)

No, like all boa cousins, anacondas kill their prey by constriction, not venom.