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Eunectes
murinus
The Green Anaconda, also known as the water boa. There is
also the yellow Anaconda, Eunectes notaeus.
The
name "Anaconda" comes from the Sri Lankan language, Sinhalese,
which originally probably referred to the Reticulated python. No
one is sure how this name came to represent a South American
snake, unless these two snakes, Anaconda and Python, were
mistaken as the same species. Both snakes are swimmers and two
of the largest snakes in the world.
The Tamil word for Anaconda is "Anaikolra" which means "elephant
killer". The early Spanish settlers referred to this snake as "Matatoro"
or "bull killer". |
Classification:
Phylum - Chordata
Class - Reptilia
Order - Squamata
Family - Boidae
Circadian Cycle - Nocturnal
Physical Characteristics
The Anaconda is considered the biggest snake in the
world. These snakes may reach lengths of over 29 feet. There
are many exaggerated stories about anacondas being much
longer, but they cannot be confirmed.
The Anaconda is the heaviest snake, but it may or may not be
the longest.The Reticulated python rivals the Anaconda for
the longest snake. A 20-foot Anaconda will weigh more than a
33-foot python. The Anaconda can weigh 550 pounds or more,
but will usually top out at a few hundred pounds. These
snakes can measure more than 12 inches in diameter. The
female typically outweighs the males.
The Green Anaconda is dark green in color with black oval
patches on its back. This drab pattern blends the snake in
well with the wet, dense vegetations of its habitat. The
sides have similar spots with yellow centers. The Yellow
Anaconda is true to its name and is mostly yellow with
similar black spots. The scales of the yellow and black
underside of the lower tail on these Anacondas have a
particular pattern which is unique to each snake. It's a
form of identification, like a human fingerprint.
Snakes have a cavity called a
cloaca which is where the intestinal and
genitourinary tracks empty. Anacondas have spurs on
either side of the cloaca. The cloaca of the Anaconda has a
gland which emits a foul-smelling musk. This brownish musk
is quite poisonous to small organisms. This may prevent
ticks and leeches from attaching themselves here. When
Anacondas are out of the water for long periods of time they
usually become infested with ticks.
The Anaconda come equipped with a large head and a thick
neck. Its eyes and nostrils are positioned on the top of the
head, enabling the Anaconda to breathe and to see its prey
while its stocky body lays submerged under water. The
extremely muscular Anaconda is a constrictor and is not
poisonous; however, it still has teeth and powerful jaws
that it utilizes to clench onto its prey. It grabs its
victim and pulls it underwater, drowning the prey.
Range: Neotropical
The Anaconda is found in the Guianas, throughout
tropical South America, east of the Andes and mainly in the
Amazon and Orinoco Basins The Yellow Anaconda can be found
as far south as Argentina.
Habitat
The various
biomes where Anacondas are usually found are
tropical rainforests, savannas, grasslands, scrub forests,
and deciduous forests. The Anaconda prefers to be in the
water, but they do enjoy spending some time on land in
shallow caves by the water's edge, or in riverbank trees to
bask in the sun.
On land they can become tick-infested and they cannot move
as quickly as they do in water. In water, they can stay
completely submerged for 10 minutes. They often lay
submerged waiting for prey. They are agile swimmers but
sometimes prefer to let the river's current carry them
downstream with only their nostrils above the watery
surface. Once they are satisfied with the change in scenery,
they simply drift to the river's edge.
Anacondas are more often found in swamps and calmer waters
than in swift-moving rivers.
Diet -- Carnivorous
They typically feed on large rodents, tapirs, capybaras,
deer, peccaries, fish, turtles, birds, sheep, dogs and
aquatic reptiles. They have been known to occasionally prey
on jaguars and attacks on humans can be confirmed, although
this is rare. Younger Anacondas feed on mice, rats, chicks,
frogs and fish.
Anacondas are usually coiled up in a murky, shallow pool or
at the river's edge. They wait to ambush their unsuspecting
prey when they come down for a drink. Anacondas bite their
prey with their sharp teeth, hold on with their powerful
jaws and pull them under water. The victim may drown first
or it may be squeezed to death in the Anaconda's muscular
coils. Anacondas, true to the Boa family, constrict their
hapless victims to death. The snake squeezes tighter each
time its prey breathes out, so the prey cannot breath in
again. Suffocation does not take long. Anacondas swallow
their prey whole, starting with the head. This is so the
legs fold up and the prey goes down smoothly. The Anaconda
can swallow prey much bigger than the size of its mouth
since its jaw can unhinge and the jawbones are loosely
connected to the skull. while the snake eats, its muscles
have wave-like contractions, crushing the prey even further
and surging it downward with each bite.
The Anaconda has a very slow-acting digestive system. After
a big meal the Anaconda will rest for several days while
digestion occurs. Many Anacondas will not eat again for
several weeks or even months, depending on the size of the
last meal. One captive Anaconda is on record for fasting
over two years!
Reproduction
Normally the Anaconda is a solitary creature that stays
within its own hunting area. This changes with the onset of
the rainy season. Courtship can last for several months with
this species. During this time, the female in breeding
condition gives off pheromones, a chemical scent, which is
tracked by nearby males. Some scientists believe the females
lay down a pheromone trial which the males follow. Others
believe that her scent is an air-borne chemical emission.
This latter theory is supported by the fact that the female
is not very active during this time and males come to her
from all directions. Males have also been observed flicking
the air to pick up the chemical presence.
Courtship and
copulation usually take place in the water. The male
presses his body to the female and rests his head on her
neck. His tongue flicks and his
spurs become erect. The spurs rub against the
female's vent region which encourages her to copulate. As he
presses his cloacal region against hers, his spurs make a
scratching sound. Copulation is complete when the female
raises her cloacal region to meet the male's. The male holds
her against him tightly by wrapping his tail and lower body
around her.
The gestation for the Anaconda is approximately 6 months.
Anacondas are
viviparous, bearing live young. A typical litter may
consist of 20-40 babies, but a female can birth up to 100
neonates. These babies are usually 2 feet long a birth. Many
newborn Anacondas refuse food for the first few months of
life. Because of their small, newborn stature, many Anaconda
babies are prey for other animals.
Within hours after birth, Anaconda neonates can swim, hunt
and care for themselves. Baby Anacondas grow rapidly until
they reach sexual maturity at the age of 3-4 years. They do
continue to grow after this time, but at a slower rate.
Life Span
Anacondas can live into their thirties.
Special Adaptations
The Anaconda has eyes high on its head so that it can stay
camouflaged underwater while watching and waiting for its
prey. Its nostrils are positioned there as well, so that it
can breathe easily while almost completely underwater.
Another form of camouflage is the Anaconda's color pattern
of dull green with black spots. This blends in with the
dense vegetation of its habitat and also with the murky
water that Anacondas love.
At Nashville Zoo
at Grassmere
If you would like to see one of the world's largest snakes,
come on out to the Park! Our Anaconda measures 18 feet long!
This amazing creature is housed in our Unseen New World
exhibit along with some other very creepy and very crawly
critters! We hope to see you soon.
Status
CITES, Appendix II
Conservation
At present, all South American countries prohibit trade
regarding the Anaconda. However, some of these countries
will allow live export for zoos and research in a limited
capacity.
The greatest threat to the Anaconda is man. Most local
people kill these snakes on sight, out of the fear that they
are man-eaters. In most instances, if an Anaconda senses
humans in the area, it will retreat in another direction.
Human death by Anaconda is quite rare. Habitat destruction
is another problem that the Anaconda faces.
There is much to learn about the Anaconda. Presently, CITES,
PROFAUNA and The Wildlife Conservation Society jointly are
conducting the first field study of the Anaconda. Hopefully
many questions will be answered by this study.
Article contributed by Lori Hamlett
Photographs courtesy of Byron Jorjorian©
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