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92 IGUANA  •  VOLUME 15, NUMBER 2  •  JUNE 2008 BARRIO AMORÓS AND MANRIQUE

The senior author with a Green Anaconda (Eunectes murinus).



“It is of unsightly body, the size of a pine beam. It can be as long
as eight varas [6.4 m; each vara is 0.8 m]. Just seeing it is fright-
ening. Knowing the range of its pestilent breath spurs one to
flight. In response to a noise, the snake lifts its head one or two
varas and fires a breath at tiger, lion, calf, deer, or man that stops
cold, stuns, and turns immobile the animal that was poisoned. It
then approaches and swallows it. I said that it swallows because it
lacks teeth. It can open its mouth widely and may spend days con-
suming its prey…”

Father José Gumilla
El Orinoco Ilustrado. 1741

During the past seven and 12 years respectively, we have
been accumulating data on the natural history of the

Green Anaconda (Eunectes murinus) in the Venezuelan Llanos.
We are wildlife guides who lead tours to this remarkable area
called Los Llanos (flat lands), an extensive region of Venezuela
and Colombia consisting of savannas north of the Orinoco
River. Some of the most impressive rivers of South America flow
through Los Llanos, leaving the plains flooded for half of the
year. The landscape is mainly grassland with scattered trees and
palms (more forested areas to the northwest are called Llanos

altos), but also dry gallery forest along rivers, many lagoons, and
palm forests (morichales). We base our activity in the small vil-
lage of San Vicente, on the shore of the Apure River, although
both of us have had experience in other areas as well. Our tour
groups are taken into the field in search of the typical fauna of
the zone: Capybaras, Giant Anteaters, Giant Amazon Otters,
Pink River Dolphins, hundreds of species of birds (raptors,
egrets, herons, screamers, terns, skimmers, parrots, toucans,
woodpeckers, ducks, storks, etc.), piranhas, Spectacled Caimans,
Green Iguanas, Mata-Mata Turtles, and, of course, the indis-
putable star of Los Llanos, the giant serpent, the Green
Anaconda. A tour in the dry season is not complete if we are
unable to find at least one of these snakes.

Among the stunning wildlife and the impressive landscapes
of the region, anacondas are perhaps the most emblematic nat-
ural element and the most intriguing to foreign visitors. The
reactions of tourists to this star of myriad tales range from fasci-
nation to fear. Herein we address the myth, the fantasy, the sci-
entific reality, the natural history, interactions with humans,
folklore within the local culture (indigenous people and descen-
dants of Europeans), and the economic importance of this giant
serpent.

The Family Boidae
The family Boidae includes some of the most beautiful and well-
known of all snake species. The colorful Rainbow Boa (Epicrates
cenchria), the elegant Emerald Boa (Corallus caninus), the slen-
der tree boa (Corallus rushenbergerii), the Red-tailed Boa (Boa
constrictor), and the impressive Green Anaconda (Eunectes mur-
inus) are all members of this family of non-venomous snakes. All
boas (subfamily Boinae) are known for killing their prey by con-
striction. The subfamily is widely distributed in the Americas
(where pythons are absent), ranging from the southern United
States to the lowlands of Bolivia and northern Argentina. Real
boas also occur in Madagascar and New Guinea, and the South
Pacific. Boas are a complex family of snakes that includes terres-
trial, aquatic, burrowing, and arboreal species and which con-
sume a wide variety of prey. All boas are live-bearers. Most boas

Observations on the Natural History 
of the Green Anaconda (Eunectes murinus
Linnaeus, 1758) in the Venezuelan Llanos:

An Ecotourism Perspective 
César L. Barrio Amorós1 and Róger Manrique

Fundación AndígenA, Apartado Postal 210, 5101-A, Mérida, Venezuela (www.andigena.org)
1Corresponding author: cesarlba@yahoo.com; atelopus@andigena.org

Photographs by the authors unless otherwise indicated.

IGUANA  •  VOLUME 15, NUMBER 2  •  JUNE 2008 93GREEN ANACONDAS IN THE VENEZUELAN LLANOS

�

A large female Green Anaconda with a total length of 5.6 m.



are nocturnal, but some Neotropical species, including the Boa
Constrictor and the famous anacondas, may hunt by day as well
as during the night.

In addition to the Green Anaconda, three other anaconda
species are currently recognized. Both are similar, albeit much
smaller. The Yellow Anaconda (Eunectes notaeus Cope) reaches a
maximum size of 4 m and lives in the Paraguay-Paraná River
Basin (northern Argentina, Paraguay, Bolivia, southwestern
Brazil). The Brazilian Anaconda (Eunectes deschaunseei Dunn
and Conant) reaches a maximum length of only 2.5 m and is
known from the mouth of the Amazon to French Guiana, were
it is sympatric with E. murinus. Recently, a third species has been
described from Bolivia as E. beniensis (Dirksen 2002; Dirksen
and Böhme 2005). It also is small (maximum length 4 m).
Another name applied to an anaconda, E. barbouri, was proven
to be a synonym of E. murinus by Strimple et al. (1997) and
Dirksen and Böhme (1998).

The Green Anaconda
Eunectes murinus, the Green Anaconda, is known as serpiente de
agua, culebra de agua, caribita, madre de agua, güio, petaca, mata-
toro, sucurí, yacu mama, camudi, and by many more names
throughout its range, which extends from Trinidad and
Venezuela to Bolivia. The species is the largest of the anacondas,
and the heaviest serpent in the world, its weight surpassing that
of other giants like the Reticulated Python. Green Anacondas
can reach 200 kg (227 kg is the record taken from the Guinness
Book of World Records 2004).

Which species of snake is the longest is a question that
engenders an ongoing debate — but the Green Anaconda is
indisputably in the mix. A maximum length of 8.3 m is widely
accepted (Murphy 1997), and no documented voucher speci-
men of greater size is available (although the Guinness Book of
World Records 2004 lists a total length of 8.45 m, but fails to cite
a source). People, especially in Los Llanos, commonly speak of
anacondas measuring dozens of meters, but like many fishing
stories, sizes tend to be exaggerated. A skin that was allegedly 12
m long proved to be only 6 m in length when accurately meas-
ured; most surprised (and disappointed!) was the owner of the
skin, who had been quite certain that it was longer (Murphy and

Henderson 1997). Many of the historical cases (Murphy and
Henderson 1997) of “scientists” reporting animals as long as 14
m and even 50–60 ft are considered unreliable as the claimants
had been unable to measure the animals in question and esti-
mates were entirely subjective. The most prominent case is that
of Emmett Dunn, an important herpetologist in Colombia,
who believed the seemingly accurate report from an oil geolo-
gist of an anaconda captured in the Río Meta that reportedly
measured 11.5 m (35.5 ft). In any event, the Zoological Society
of New York is still offering a prize of $50,000 for an anaconda
longer than 30 ft! Only females can reach the largest size; the
longest males do not surpass 4 m (pers. obs.). Of interest, how-
ever, are reports of enormous anaconda skins, such as one
allegedly 29 ft in length (Robertson 1998) or those reported in
Murphy and Henderson (1997). Snakeskins, once separated
from the flesh, salted, and stretched, can increase in length by as
much as 30%, giving the impression that the snake was consid-
erably longer than it actually was when alive.

The ground color of Green Anacondas typically is olive-
green, with round black spots and yellow ocelli surrounded by
black on the flanks. The belly is yellow with black checks. One
red and one black stripe immediately behind the eyes are distin-
guishing features that help differentiate species of anacondas. 

Taxonomy
The Northern Green Anaconda was long known as Eunectes
murinus gigas (Latreille), the largest of all anacondas. Differences

94 IGUANA  •  VOLUME 15, NUMBER 2  •  JUNE 2008 BARRIO AMORÓS AND MANRIQUE

The Green Anaconda is the largest boa (Family Boidae, Subfamily Boinae) and the heaviest snake in the world.

The ground color of Green Anacondas typically is olive-green, with
round black spots and yellow ocelli bordered by black on the flanks.



IGUANA  •  VOLUME 15, NUMBER 2  •  JUNE 2008 95GREEN ANACONDAS IN THE VENEZUELAN LLANOS

distinguishing this race included a lighter postocular region and
slight differences in scale counts. However, as Dirksen and
Böhme (1998) indicated, this color pattern is widespread
throughout the range of E. murinus, and scale counts do not dif-
fer consistently. Consequently, Eunectes murinus (Linnaeus
1758) is now recognized as a single monotypic species.

Distribution
The Green Anaconda has a continuous distribution from north-
eastern Venezuela and Trinidad to Bolivia, through the Orinoco
and Amazon basins. It is currently unknown west of the Andes
(but see below). In Venezuela, it is found throughout the low-
lands in the states of Sucre, Monagas, Anzoátegui, Bolívar,
Amazonas, Apure, Barinas, Guárico, Cojedes, Portuguesa, and
probably the southern parts of Aragua and Carabobo.

Lake Maracaibo is a large brackish Venezuelan lake con-
nected to the Gulf of Venezuela by a 55-km strait. The presence
of Green Anacondas in Lake Maracaibo has not been confirmed,
although local people are familiar with a “Madre de Agua” liv-
ing in the deep pools of associated rivers and lagoons. They fear
the animal, but respect it because they believe that these giants
protect the rivers. Two guides who have worked with us report

road-killed anacondas. Although these men are not trained her-
petologists, they lead wildlife tours to Los Llanos and are capa-
ble of identifying the species. No vouchers exist, however, and
so we cannot confirm the presence of these snakes until we have
more solid evidence.

Habitat
Anacondas are aquatic snakes. They prefer to keep the entire
body under water, with only the eyes and nares above the water
line. When basking, they rarely range more than one meter from
water. Anacondas living in rivers have continuous water access,
but those living in swamps are subjected to the risk of drought
during the dry season. They sometimes remain burrowed in
mud for months until the swamp refills in the rainy season.
However, we have observed dead anacondas in dried swamps far
from any permanent water.

Coiled anacondas are commonly seen basking in the sun
on riverbanks or even in the shadow of overhanging vegetation.
They may seek refuge in burrows and natural holes, where they
are easy to find along rivers during the dry season. In the rainy
season, they move throughout the flooded savannas, and are
almost impossible to find.

Green Anacondas have a continuous distribution from northeastern Venezuela and Trinidad to Bolivia, through the Orinoco and Amazon basins.
In Venezuela, the species is known from throughout the llanos.



Anacondas are not arboreal, but we have on occasion found
individuals resting in trees as high as 4 m above the ground.
These are likely to be subadult females or adult males rather than
heavy adult females.

Abundance
Although snakes in the tropics are never as common as they are
depicted in the movies, given the proper conditions and habitat,
anacondas can be quite numerous. In the rainy season, when the
plains are flooded, anacondas, like many animals, are widely dis-
tributed throughout the savannas and difficult to locate. In the
dry season, however, when the water evaporates from the lagoons
and the rivers are at minimal flow, animals cluster around the
remaining rivers and lagoons. At this time, Los Llanos provides
spectacular views of thousands of Spectacled Caimans, birds, tur-
tles, and Capybaras together on the shore of a single body of
water. In these conditions, anacondas, although not as visible as
other animals, can be extraordinarily abundant. Along one five-
km stretch of the Apure River, our record is 16 anaconda sight-
ings in three days. The average is always lower, from one to four.
In swampy areas, they can be even more concentrated. The sum-
mer dry season also coincides with the breeding season, and
females may be accompanied by several males.

Reproduction
One legendary aspect of anacondas is their size… No llanero will
admit that anacondas can only reach 8, perhaps 9 m in length.
All of them have seen at least once in their lives anacondas of 15,
20, or even 40 m. And it is impossible to claim otherwise! They
are right, and you are a “gringo” who does not know anything!
On one occasion, a llanero came to us, and said that he had seen

96 IGUANA  •  VOLUME 15, NUMBER 2  •  JUNE 2008 BARRIO AMORÓS AND MANRIQUE

Anacondas are aquatic. Typically, the entire body is under water, with
only the eyes and nares emergent.

Despite their large size, Green Anacondas may be hard to locate. For
example, the presence of the species in Lake Maracaibo has not been
confirmed despite reports from reliable sources, and no voucher speci-
mens have been taken.

Coiled anacondas are commonly seen basking in the sun on riverbanks
or even in the shadow of overhanging vegetation. They may seek refuge
in burrows and natural holes, where they are easy to find along rivers
during the dry season. In the rainy season, they move throughout the
flooded savannas, and are almost impossible to find.

A Green Anaconda resting by day in vegetation along a riverbank.
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Anacondas are not arboreal, but smaller, lighter individuals may bask
in trees to heights of 4 m.



The Green Anaconda (Eunectes murinus) is one of the longest and certainly the heaviest snake in the world. 

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As one of the remaining top predators of the Venezuelan Llanos, effective conservation of Green Anacondas may depend on education and the benefits pro-
vided through ecotourism. See article on p. 92.

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Last Chance for the Yangtze Giant Softshell Turtle? The world’s rarest and most endangered turtle, Rafetus swinhoei, may be getting a reprieve from
impending extinction. With only four known living individuals (two in China, two in Vietnam) and only one of these a female, the odds couldn’t be
much worse. In early May 2006, the Turtle Survival Alliance (TSA), in conjunction with the Wildlife Conservation Society, coordinated the successful
transport of the lone female from the Changsha Zoo to the single male (estimated to be 100 years old) at Suzhou Zoo, for a desperation captive breed-
ing attempt. “Team Rafetus” breathed a collective sigh of relief when the pair first met and gently began a courtship process that culminated with breed-
ing attempts. The female, affectionately known as China Girl, is shown here basking with the male watching her from the water. Fingers are crossed that
she will lay fertile eggs in June. For more information on this historic event, go to the TSA web site at <www.turtlesurvival.org>. See also the Newsbrief
on p. 124.

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Proud sponsor of the IRCF 
and this centerfold



The Grand Cayman Blue Iguana (Cyclura lewisi) remains one of the world’s most endangered lizards. A brutal attack at the breeding facility on Grand Cayman
resulted in the death of seven captive adults. Local and international efforts continue to support the Blue Iguana Recovery Program. See article on p. 66 and
Travelogue on p. 106.

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Ground lizards, such as the Dominican Ground Lizard (Ameiva fuscata, left), and anoles, such as the Grand Cayman Blue Anole (Anolis conspersus), are
among the most abundant and visible species on West Indian islands. However, ground lizards have become rare or extirpated on islands where introduced
mongooses (Herpestes javanicus) are established, and the native anole on Grand Cayman shifted its structural niche when it came into competition with
introduced Cuban Brown Anoles (A. sagrei). See Commentary about an appreciation of “common” species on p. 105.

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IGUANA  •  VOLUME 15, NUMBER 2  •  JUNE 2008 97GREEN ANACONDAS IN THE VENEZUELAN LLANOS

a huge anaconda of at least 20 m, and that he knew where it
was. So we ran to the site and, after some hours in the swamps,
we actually saw an amazing ball of anacondas — probably 20 m
long — but not one, instead 14 anacondas — 13 males trying
to mate with one huge female!

This is representative of anaconda mating. In the dry sea-
son, large females release pheromones that attract males from
many kilometers. The first male to find the female is likely to
remain for days (or even weeks) coiled around her. Inevitably,
other males are attracted as well, all of them surrounding the
female and competing to introduce one of their hemipenes into
the female’s cloaca. This orgy is essentially a patient battle among
the males who are not aggressive toward each other (Rivas et al.
2007).

An interesting feature of anacondas, and many other boids,
is the presence of small “spurs” adjacent to the cloaca, with those
of males larger than those of females. The spurs are mobile, and
may assist in mating by stimulating the female’s cloaca for recep-
tion (Rivas et al. 2007).

After 6–7 months of pregnancy, the female gives birth to
8–82 baby anacondas (usually 20–40). Newborn anacondas
usually are 60–80 cm in length, lighter in color (bright yellow)
than the adults, and very aggressive.

Prey
One of the most fascinating aspects of large serpents is their
feeding habits. What do huge snakes eat? A Green Anaconda
may wait for hours, sometimes days or weeks, hidden underwa-
ter, with only nostrils and eyes above the surface. When prey
approaches, it will attack at close quarters with lightning speed,
wrapping its coils around the prey animal and killing it.

Prey items vary according to the size of the snake. Juveniles
prey on small mammals, frogs, and large invertebrates, gradually
taking larger items as they grow. A giant female of 6 m can swal-
low a Capybara or a pig. Although stories abound of anacondas
swallowing cows and bulls, no such instances have been docu-
mented in Venezuela.

Enemies
Adult anacondas are at the top of the feeding pyramid, but the
young are eaten by many birds (e.g., storks, raptors, herons),
Spectacled Caimans (Caiman crocodilus), and a wide variety of
carnivorous mammals. The notion of a fight between a giant
anaconda and a jaguar is purely a Hollywood fantasy. We can-

not imagine that any jaguar would be stupid enough to attack a
giant serpent, but smaller anacondas make easy prey for experi-
enced big cats.

One of the most striking features of many anacondas of all
sizes is the number of wounds, old and recent, on their bodies.
Many are attributable to piranhas (Serrasalmus sp. or Pygocentron
sp.), which apparently bite and release, leaving a nasty wound.
Others are from Spectacled Caimans, powerful predators that
can put up a good fight when the tables are turned. Anacondas
usually heal well, and most show old scars in the form of a half-
moon or a complete circle from piranha bites or parallel linear
wounds from caimans. Some snakes, however, can die of such
bites. Other common injuries include incomplete tails. Some of
these short-tailed anacondas are easy to recognize even when
recaptured years later. One unusual wound observed in an adult
female was the absence of the left eye, with the area almost com-
pletely covered with scales.

Anacondas can be cannibalistic. Rivas and Owens (2000)
documented three cases, two of them females eating smaller
males at the end of the breeding season. They speculated that
the females ate the males immediately after mating.

The primary enemy of anacondas is humans. In almost any
encounter between the two, snakes are systematically killed. We
see them dead on the road (cars never stop or go around), killed
by campesinos when encountered in the field, and, on one sad
occasion when it was too late to intervene, we saw a fisherman
pouring fuel and setting fire to a complete ball of breeding ana-
condas. Attitudes, at least in areas with a strong tourist presence,

After 6–8 months of pregnancy, females give birth to 8–82 (usually
20–40) baby anacondas.

Newborn anacondas are 60–80 cm long, lighter in color than adults,
and very aggressive.



show signs of change, but fear of snakes is very deep-rooted in
the human psyche and rational appeals proceed at a limited pace.

Do Anacondas Attack Humans?
Like any other animal in the world, anacondas do not like to be
bothered by annoying guides who want to show them to
tourists. Predictably enough, anacondas will defend themselves
energetically, biting and voiding their bowels when handled. An
anaconda bite is not venomous, and, depending on the size of
the snake, can be like a cat scratch or a Rottweiler bite. Since the
snakes are aquatic, their mouths contain bacteria that can infect
a wound. In some cases, anaconda teeth can break off and
become embedded in a wound, only to surface months later.

Anacondas longer than 5 m can cause severe injuries, and
the long teeth can penetrate to the bones of a hand, for exam-
ple. An infected bite can also be quite serious and require hos-
pital care. A few cases reported in the literature describe appar-

ent attacks by anacondas. One in Murphy (1997) involved a
young girl caught by her bathing suit and saved by her sisters.
The size of the snake is not mentioned. Rivas (1998) mentioned
two attacks on his helpers during field surveys in swamps. One
of the anacondas measured 5.04 m and the other 4.45 m, and
Rivas indicated that both attacks appeared to be predation
attempts. An anaconda of 6 m could easily swallow a child or a
small adult, and an animal of 8 m could swallow an adult of any
size. To be caught, a person would have to be exceedingly care-
less, asleep, or drunk. As with prey of a similar size, the snake
would take several hours to swallow its meal and weeks or even
months to digest it.

Sensational stories of anacondas attacking humans have
cropped up in popular literature for centuries. Some of these epic
and not very realistic accounts were addressed by Murphy and
Henderson (1997). Fortunately, no reports of such incidents exist
from Venezuela, although rumors of missing persons suspected
of having run afoul of anacondas can be heard from local llaneros.

Capturing Anacondas: 
Defensive Behavior, Bites, and Other Annoyances

When observed along the river during the day, anacondas usu-
ally are resting, basking in the sun on the shore completely
exposed, or, more commonly, concealed to some extent in tall
grass, in paleras (floating mats of logs and branches), or sub-
merged with only the nares and eyes exposed. They are more
active at night, when they move along shorelines or swim in the
shallow water near the riverbank. Capturing an anaconda is
never easy. We first try to catch a glimpse of the neck. If the ani-
mal is resting and the neck exposed, our task is much simpler.

98 IGUANA  •  VOLUME 15, NUMBER 2  •  JUNE 2008 BARRIO AMORÓS AND MANRIQUE

One of the most striking features of many anacondas of all sizes is the
number of wounds, old and recent, on their bodies. Many are attrib-
utable to piranhas (Serrasalmus sp. or Pygocentron sp.).

The principal enemy of anacondas is humans. In almost any encounter
between the two, snakes are systematically killed. We see them dead on
the road (cars never stop or go around) and killed by campesinos when
encountered in the field.

Green Anacondas select prey according to size. Juveniles prey on small
mammals, frogs, and large invertebrates, gradually taking larger items
as they grow. A giant female 6 m in length can swallow a Capybara or
a pig. This juvenile killed a small Common Caiman (Caiman crocodi-
lus); note the wounds inflicted during an earlier battle with another
prospective meal.

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IGUANA  •  VOLUME 15, NUMBER 2  •  JUNE 2008 99GREEN ANACONDAS IN THE VENEZUELAN LLANOS

The snake will allow a close approach, and usually the catch is
successful. If the head is hidden, we must touch the animal until
it starts to move. Once we see the head, we can catch it. If the
animal is in the water and the head submerged, we usually grasp
the body, and risk being bitten. Especially the smaller, more
agile, and aggressive males will turn quickly and strike — but
generally we manage to restrain the animal. Some guides use
gloves, which are useful to avoid bites, but we tend to be some-
what masochistic and always try to capture the animals by hand.
Anacondas can bite underwater, and, on occasion, we have been
surprised by an angry male biting our feet.

We have received dozens of bites, some severe. A bite is
inevitably painful and bloody. Teeth of large individuals can pen-
etrate to the bone. Only rarely have we decided to leave the ana-
conda catching for another day due to the severity of injuries.
Females are bigger but also calmer and quieter than males, and
easier to catch. Once one of us has the neck, we can move or lift
the animal depending on its weight. Males are lighter, and we
can deal with adults to 3 m in length without too much diffi-
culty. An adult male of 3 m can weigh 5–7 kg. Females are a dif-
ferent question. A subadult female of the same size can weigh
twice as much, depending on its girth and whether it has prey
in the stomach. Usually females of more than 4 m are difficult
or impossible for a single person to lift. The senior author
recently captured an impressive female of 5.5 m, so thick that it
was impossible for three people to move it! We estimate that it
weighed more than 100 kg! An animal of more than 6 m
requires at least four people to move it out of the water, and at
least 10 people are necessary to lift it.

Other than striking, an anaconda, when secured by the
neck, releases a horribly offensive musk from its cloaca. If it
splatters skin or clothing, the odor can persist for hours! The
stench is truly vile. We quickly wash the cloacal region of any
recently captured anaconda, until it releases all the musk into the
water. 

Once an individual has been shown and photographed by
all interested parties, it is released in the same spot where it was
captured. After handling, some anacondas become very calm
and will remain for a while in the same position in which we
leave them. Others disappear quickly. A few adopt a balling
defensive posture (Dirksen et al. 1998), in which the snake coils
into a ball to protect the head.

Myths
Anacondas are said to produce a powerful and poisonous vapor
(Gumilla 1741) capable of stunning victims. Similar beliefs are
common to several cultures throughout the world, and especially
strongly ingrained in Spain and all of Latin America. Many
llaneros are particularly fervent believers.

Another common legend tells of a giant anaconda (invari-
ably much more than 6 m in length) coiled in a tree overhang-
ing a pool of water with its tail securely wrapped around a
branch, waiting patiently until a cow or bull arrives to drink at
the pool. Once the snake catches the snout of the ruminant, the
anaconda will firmly grip it while stretching out elastically to an
incredible length. When the prey is exhausted, it is killed and
the snake will release its tail and proceed to swallow the animal.

Another myth refers to finding an immense anaconda rest-
ing and digesting with the horns of a prey animal (either a White-
tailed Deer or a cow) sticking out of its mouth. According to
llaneros, the anaconda will wait until the horns drop naturally as
the rest of the animal is digested. Murphy and Henderson (1997)
gave little credence to these tales (although horns of prey are
known to have survived digestion by pythons in Africa).

Conservation
Little is known about the roles of the top predators in Los
Llanos. In addition to the anacondas, top predators include
Jaguars, Pumas, Orinoco Crocodiles (Crocodylus intermedius),

When handled, anacondas will defend themselves energetically, biting
and voiding their bowels. An anaconda bite is not venomous; however,
the snakes are aquatic and their mouths contain bacteria that can infect
a wound. In some cases, anaconda teeth can break off and become
embedded in a wound, only to surface months later. Note also the
round “hole,” the opening of the glottis, which can be extended
between the lower jaws, allowing the snake to breathe when swallow-
ing large food.

Capturing large anacondas is a risky proposition.



Spectacled Caimans, Pink River Dolphins, and Giant Amazon
Otters. The two biggest predators, the Jaguar and the Orinoco
Crocodile, have almost totally disappeared, and Pumas and
Giant Otters have become very rare, leaving anacondas and
Spectacled Caimans as the principal top predators. The vast
llanos ecosystem depends mostly on these two predators and the
scavengers (piranhas, vultures, and other raptors) to keep the
environment clean and healthy. Of course, alterations by
humans have changed the natural interactions between prey and
predators by introducing cattle, hunting deer and Capybaras,
and over-fishing. Some almost untouched llanos ecosystems
remain in national parks, but most private preserves have been
substantially altered, although no hunting is allowed. To protect
cattle, large predators are exterminated, and then natural prey,
such as Capybaras and deer, increase in numbers well beyond
the natural carrying capacity. Anacondas thus fulfill a very
important role — if they are not killed.

Advocating protection for snakes is always difficult, but
attitudes show signs of changing. We see fewer anacondas killed
now than we did years ago. People use them less for natural
medicine (although some still believe that the fat is miraculous
for rheumatism). On one occasion, we rescued a huge anaconda
of 4.5 m that was kept by a local fisherman who wanted to
extract the fat and sell it for a high price.

Anacondas remain quite common in some areas. Endless
swamps are not amenable to humans, yet provide ideal habitat
for giant serpents. Also, big rivers and small tributaries offer
many opportunities for anacondas to live and hide with little
disturbance. The most important aspect of conservation is to
convince llaneros to value and protect their natural heritage.
Educational campaigns, posters, lectures in local schools, and
demonstrations show that anacondas are not dangerous and can
be economically important as an attraction for tourists. 

Can Ecotourism Protect Anacondas?
In the past ten years, we have shown hundreds of anacondas to
tourists from all over the world. We believe that personal con-
tact with anacondas is necessary to convey the conservation
message. We generally capture one specimen per group (and
usually show many more), and make everyone feel the power
of its muscles, feel its skin, see the colors, and even experience
the terrible smell. When a tourist is faced with an anaconda,
even if held by one of us, reactions are diverse, ranging from
excitement, fascination, and admiration to abject fear. Even
many who are scared at first will eventually agree to touch or
even to hold one of these animals and, in the process, perhaps
reconsider the idea that all serpents are evil. Having at hand one
of nature’s most powerful predators and seeing it in its own
habitat is a unique experience, which we hope will give visitors
an idea of the importance of preservation. When these people
return to their cold homes in Sweden, England, or Canada, and
tell incredible stories to their friends, some of them in turn
want to see the show live! This as much as any other single fac-
tor has led to an increase in ecotourism in Los Llanos — with
the primary objective of seeing, among the other spectacular
animals, anacondas. Eco- or bio-tourism operators (at least the
most serious) offer work to many people in Los Llanos, boat-
men, local guides, cooks, etc. They and the people around them

(family, friends, neighbors), all fishermen, and other potential
enemies of anacondas and other animals in time will see the
value of protecting these animals, recognizing that they attract
tourists and thus, money for the village.

What are the Negatives?
During the rainy season, when Los Llanos are flooded, the huge
concentrations of birds and caimans, turtles and piranhas dis-
perse into the flooded savannas and become difficult to see. In
Venezuela, the rainy season extends from mid-May to mid-
November. Anacondas also are much harder to locate and,
although we advertise this fact, tourists may be disappointed.
Inevitably, entrepreneurial llaneros will capture any anaconda
they can find (and keep it in a bag for weeks or until it dies or
is too weak or thin to be interesting) and offer to show it for a
price. Others tie a rope around the neck of a big snake and keep
the animal in a swamp until the tourists arrive with a local guide,
at which time the giant suddenly appears (always with neck
injuries) to the delight of tourists unaware of the fraud. Such dis-
honest practices can penalize “honest” guides, but is this truly
negative? The impact is not pronounced; only a few anacondas
serve as bait, and the educational aspect for the tourists can be
more positive than if they do not see any snakes. Nevertheless,
it presents a false image of nature, and we do not engage in or
approve of such dishonesty.

100 IGUANA  •  VOLUME 15, NUMBER 2  •  JUNE 2008 BARRIO AMORÓS AND MANRIQUE

The two largest predators of the Venezuelan Llanos, the Jaguar and the
Orinoco Crocodile, have almost totally disappeared, and Pumas and
Giant Otters have become very rare, leaving anacondas and Spectacled
Caimans as the principal top predators.



IGUANA  •  VOLUME 15, NUMBER 2  •  JUNE 2008 101GREEN ANACONDAS IN THE VENEZUELAN LLANOS

Some tourists do not want to touch snakes, only observe
them, not out of fear, but because they claim that we stress the
animals. Yes, this is likely true. However, reptiles do not stress
like birds or mammals, due to their slower metabolism. Usually,
big snakes like anacondas, but also smaller boids, iguanas, and
caimans, fight for a short period when captured and then cease
to move, as if in a trance… This is the perfect moment to show
them to people, to take pictures, and in a few minutes, the ani-
mal is free again, at the same location. Only a few animals are
caught and used as live teaching material, always with concern
for the well-being of both captor and captive. They always are
released quickly, and often become wary of being captured again
(minimizing any potential stress). Some anacondas, however,
have been recaptured several times, and they always seem to be
in perfect shape.

Future Perspectives
Much remains to be learned about the natural history of ana-
condas and we would like to do our part. We have the ability to
follow populations of anacondas at little cost. We can mark,
photograph, measure, and release anacondas whenever we take
tourists to Los Llanos. Attaching radio transmitters to some of
these animals and tracking them, especially during the rainy sea-
son when the savanna is flooded and the anacondas disappear
from the river shores, would surely provide much insight into
the lives of these intriguing serpents.

Acknowledgements
We are indebted to Arassari Trek (www.arassari.com), the com-
pany for which we have been working for many years. They
have made it possible for us to develop our interest in nature
directly in Los Llanos. We also are grateful to the many llaneros
who have worked with us for more than 10 years: Azael, Carlos
Andrés, Dixon Güiza, Luison, Asdrúbal, and many others.
Robert Henderson and Lutz Dirksen provided valuable infor-
mation and helped correct our English, improving the manu-
script dramatically.

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When a tourist is faced with an anaconda, even if held by one of us,
reactions are diverse, ranging from excitement, fascination, and admi-
ration to abject fear.

We believe that personal contact with anacondas is necessary to con-
vey the conservation message. We generally capture one specimen per
group and let everyone feel the power of its muscles, feel its skin, see
the colors, and even experience the terrible smell.




