Few animals conjure up the awe, fear, and mystery invoked by anacondas, the world’s most massive serpent.
Although herpetologists have made extensive studies of most of the world’s 3,500 other species of snakes, the anacondas of the South American jungles remain poorly understood.
Anacondas are huge, dangerous, and have nasty tempers.
Studying them is difficult. But the little that is known about these giant snakes makes a set of fascinating facts.
Anacondas Grow up to 30 feet (10 meters) long
Anacondas are the world’s largest snake and the world’s second-longest snake. (Reticulated pythons can grow slightly longer.)
They grow 20 to 30 feet (6 to 10 meters) long.
There is general agreement that their bodies may be a foot (25 cm) thick, and they can weigh up to 500 pounds (240 kg). But there are exceptions to the rules:
- The nineteenth century biologists Henry Walter Bates and Alfred Russel Wallace recorded rumors about anacondas up to 40 feet (13 meters) long, but were never able to confirm them.
- The longest anaconda skin in a museum is 37.3 feet (11.4 meters) long.
- In the early 1960s, explorer W.L. Schurz measured an anaconda that was 3 feet 8 inches (112 cm) around and 27.8 feet (8.46 m) long.
- A female anaconda shot in Nariva Swamp on the island of Trinidad had a 4-1/2 foot (1.5 meter) caiman in its stomach.
Ancient anacondas were even larger than modern anacondas. Paleontologists have found a possible ancestor of modern anacondas known as the Titanoboa.
It was 43 feet (14 meters) long and weighed up to 2500 pounds (1200 kg). It was capable of hunting crocodiles.
It lived at a time the Amazon was 6 to 8 degrees Fahrenheit (3.5 to 4.5 degrees Celsius) warmer than today.
Anacondas are Night Hunters
Anacondas usually hunt at night. They spend most of their time in the water.
They keep their eyes and nostrils just above the water and the rest of their bodies concealed beneath the surface so they can ambush their prey.
Anacondas can swim at high speeds to nab an animal (or a human) walking near the water or stopping to drink.
They wrap their bodies around their victims and suffocate them before swallowing them whole.
Young anacondas feed mostly on small birds and young caiman (a smaller relative of the alligator).
Larger anacondas will eat almost anything they can find, including deer, tapirs, capybaras, turtles, pudus (small deer), and adult caimans.
There have also been documented cases of anacondas eating humans.
There are Anacondas in the United States
The US National Geographic Survey reports that green anacondas have been sighted in the Big Cypress Swamp and along the St. Johns River in central Florida.
There may be an established stand of anacondas near Kissimmee, Florida.
These anacondas are believed to be descended from escaped pet snakes.
Anacondas have Natural Enemies
As many as 99 percent of all anacondas are killed by other animals the first year after they are born.
Anacondas can eat capybaras, the world’s largest rodent. The capybara is a relative of the guinea pig that grows up to 4 feet (130 cm) long and can weigh up to 146 pounds (66 kg).
However, a group of capybaras may preemptively attack an anaconda to protect their young.
Anacondas eat caimans, a relative of North American alligators, and caimans eat anacondas.
Larger female anacondas are especially in danger of caiman attacks right after they have given birth.
Anacondas can be attacked by piranhas, but this is a relatively rare event. Piranhas need highly oxygenated, running water, while anacondas prefer to hunt in still water filled with lots of vegetation.
Anacondas Can Grow “Horns”
Biologist Dr. Jesús A. Rivas reports that when an anaconda’s head is injured, it may grow dense scar tissue that resembles a horn.
These horns do not, as some legends suggest, then grow into antlers after the anaconda eats a deer.
Anacondas Don’t Bite Very Hard
Anacondas can unhinge their jaws to swallow prey that can be more than three times as wide as they are.
However, the ability to uncouple the jaw comes at the expense of not being able to bite down hard.
An anaconda bite may not even break the skin, although its constrictor muscles can kill.
Anaconda Teeth Curve Backward
An anaconda’s teeth are designed to hold its prey so it can swallow it whole.
They are like backward-pointing needles. When someone is bitten by an anaconda, it’s important to use the other hand to grab the snake’s neck so it will let go.
Trying to pull a hand out of an anaconda’s mouth just results in both hands getting caught by the anaconda.
People who have been bitten by anacondas and escape often report that the teeth do not break the skin.
They just leave needle-like impressions. The anaconda can easily break a tooth and develop gingivitis.
Anacondas Can Injure Themselves when Feeding
Anacondas can injure themselves while feeding. Sometimes an anaconda will wrap itself around a stick while smothering an animal, and then swallow the stick.
There are recorded incidents of an anaconda impaling its eye on a stick from inside its mouth.
It’s not unusual for anacondas to die when they try to swallow non-food items along with their prey.
They have Bad Breath
People who have escaped being eaten by anacondas and scientists who study anacondas in the jungle report that these snakes have severe halitosis.
Head is the only vulnerable part of Anaconda’s body
Anacondas instinctively roll into a ball to hide their heads when they are threatened.
The anaconda can still use the rest of its body to form a “muscle loop” around the aggressor, immobilizing them.
This can happen when someone tries to touch an anaconda in its defensive state.
The snake quickly wraps itself around the person who touches it so escape is necessary for survival.
Anacondas Kill Handlers with the “Evil Loop”
More often than not, people attempt to hold anacondas by placing one hand on the head and the other hand somewhere else on the snake’s body.
A big anaconda can send a loop up from its upper body to protect its head. This makes the handler lose his or her grip on the snake’s head.
Once the snake’s head is free, it uses its body to wrap around both hands of the handler and a tragic situation may result.
Dr. Jesús Rivas says that it is possible to use this situation to the handler’s advantage. Anacondas are so determined to protect their heads that they will not attempt to constrict the person holding, which they could.
Anacondas experience a “burn” like an athlete working out very hard when they use their constrictor muscles.
If a handler just holds the anaconda’s head long enough, it will wear itself out and make capture easy.
This assumes, of course, that it doesn’t occur to the anaconda that it can crush the human handling it any time it wishes.
Rivas reports that focusing on the first 3 feet (1 meter) of a snake’s body, he did not have to deal with the power of the other 15 feet (5 meters) of the anaconda.
Stepping on an Anaconda is not Necessarily Dangerous
People who step on resting anacondas by accident are not unusually attacked. (That doesn’t mean you should hang around to see what happens!)
Because anacondas have very few predators in nature, they do not react quickly to other animals, including humans, when they are not hungry.
Even captured anacondas are usually not aggressive.
Smaller snakes, on the other hand, which have many natural predators, may become very aggressive when disturbed or threatened.
Slow Moving Anacondas are Sending a Signal that They Want You to Go Away
When an anaconda moves slowly in someone’s direction and makes a biting gesture, it is telling that person to go away.
If the anaconda wants to attack, it can move very quickly.
Wrestling Anacondas Depends on Getting Them Very Tired First
From time to time photographers and performers team up to “wrestle” anacondas, the human wrestler always winning the match.
This is possible if the snake has already been fed recently and is tired out by handling earlier.
Breed in “Balls”
Anacondas breed during the rainy season, usually in April and May.
Female anacondas release pheromones that males can use to find them and then wait for the males to arrive.
As many as 12 males will arrive at the same time, and for the next several weeks they will all writhe in a ball, each male trying to grasp onto the female for breeding.
Snakes born in the same clutch may have different fathers.
Don’t Lay Eggs
Unlike most other snakes, anacondas don’t lay eggs. Instead, female anacondas bear live young.
The pregnant anaconda carries her young for six or seven months and then gives birth to as many as 100 baby snakes.
An anaconda may lose as much as half of her weight when she gives birth.
Also read: What Snakes Give Live Birth?
Seldom Eat Fish
Even though they spend most of their time in the water, anacondas almost never eat fish.
The reason is that fish like piranhas and catfish may bite back.
Even after they have been swallowed, these fish can bite the anaconda that eats them from the inside out.
Female Anacondas are Sometimes Cannibalistic
Female anacondas carrying a clutch of fertilized eggs sometimes capture and eat male anacondas.
They do not, however, necessarily eat their males.
Male anacondas are smaller than females, and a passing male anaconda may just be an easy source of nutrition for the female while she is feeding her eggs.
Anacondas Can Catch Colds and Flu
Anacondas can catch “serpentoviruses” that cause colds and flu, sometimes even causing fatal kidney disease.
These viruses are more of a problem for snakes in zoos than in the wild.
People cannot catch infections of serpentoviruses.
Wildlife Biologists Can Put an Anaconda in a Muzzle
When wildlife biologists want to measure an anaconda in the wild, they catch it and put a dry cotton sock on its head.
They place the toes of the sock over the snake’s nostrils, so it can breathe. Then they use duct tape to keep the snake’s mouth closed and to hold the sock on the snake.
Blindfolding and muzzling the anaconda makes it calm enough to be handled.
The main danger of this procedure is to the snake.
It must not be left unsupervised, or the sock may slip so it will not be able to breathe. Removing the sock and duct tape is done very, very quickly.
Measuring Live Anacondas is a Challenge
Anacondas don’t like to be stretched out so they can be measured with a ruler.
Wildlife biologists let them curl up into a ball.
Then they measure the circumferences of the ball and the width of each coil of the snake’s body and compute the snake’s length.
Can Reproduce by Parthenogenesis
Ana the Anaconda at the New England Aquarium gave birth to a clutch of baby snakes without mating.
Ordinarily, anacondas do not have any difficulty reproducing in captivity, so the Aquarium created a display with just three female snakes.
When one of them became pregnant anyway, most of its clutch was stillborn but two survived and are doing well.
The offspring created by parthenogenesis are always female, and, in theory, also capable of giving birth to female offspring without mating.
Anacondas can hold their breath
Anacondas don’t breathe under-water, but they can hold their breath for as long as 45 minutes before they have to resurface.
Wild Anacondas can have Parasites
Although very few animals can kill an anaconda directly, these giant snakes are susceptible to many parasites.
Giant leeches, up to a foot long, may attach to an anaconda where it has been wounded or where its skin has grown thin.
During the dry season, many anacondas are infested with ticks, and during the wet season, nearly all anacondas are affected by a reptilian version of malaria.
Anacondas Can Get Cancer
Even though anacondas live in the wild, they can get cancer.
They are especially susceptible to lymphosarcoma, a kind of cancer that occurs after tissues have been injured in a fight or an accident.
Breeding Females Do Not Feed While they are Pregnant
Gestating females do not feed until they give birth. They find a place where they can bask in the sun and stay there.
Once the young snakes are born, the mother pays no attention to them.
She sets out to find new prey to gain back weight.
Eating Large Animals is Dangerous for Anacondas
Even though adult anacondas can eat large animals, even animals as large as humans, eating large animals is dangerous for them.
There are some animals that an anaconda cannot kill by constriction, such as turtles. The anaconda has to drown the turtle by holding it underwater for 30 to 45 minutes.
During that time, it is vulnerable to attack by caimans and crocodiles. When the anaconda tries to eat the turtle, the shell may puncture its esophagus, killing it.
There are other animals, such as the larger caimans, that can be impossible for the anaconda to swallow. a large animal can get caught in the snake’s throat and decompose there.
The snake will regurgitate the animal or eventually die of starvation because it cannot feed again.
A large animal’s immune system holds bacteria in its gut in check as long as it is alive.
When it dies, it begins to decay from the inside out. An anaconda must be able to start digesting the animal before it begins to decay or the anaconda can get very sick.
Can be Kept as Pets
Healthy adults who have the physical strength to deal with an anaconda sometimes have success keeping them as pets.
It’s always best to get an anaconda that was born and raised in captivity.
Captive-bred anacondas are less likely to have parasites and more likely to be used to being handled.
Your city or county may have special rules for keeping anacondas, and your state or province may require you to get a permit to keep them.
Anacondas need special enclosures.
They need a terrarium at least 6 feet (2 meters) long that can be kept between 76 and 82 degrees Fahrenheit (25 to 28 degrees Celsius) all year round.
They need a warmer area for basking on a rock and a smaller area where they can completely submerge themselves underwater.
Anacondas have large bowel movements that have to be removed quickly to keep their cage from becoming a cesspool.
Their water has to be filtered and recirculated to keep it from becoming stagnant.
Anacondas can be kept in a dry enclosure, but then special attention must be paid to humidity.
Pet anacondas have to be fed jumbo rats, guinea pigs, or rabbits. If the idea of feeding your anaconda bunnies bothers you, you should get a different pet
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