The man who loved Anacondas!

Lionel WIJESIRI

This is the story of a man who had a job that would keep most of us lying awake at night hoping to keep the nightmares at bay but he loved his job because he is man who has followed his passion, and his passion is giant snakes: the green anaconda to be specific, the largest snake in the world. His name is Dr. Jesús Rivas.

Dr. Rivas has always been fascinated by snakes and other wildlife, ever since he was a boy growing up in Venezuela. He didn’t really get an opportunity to get up close and personal with snakes until he was a teenager and eagerly volunteered his time at a local zoo.

Part of his responsibilities at the zoo was to clean the animals’ pens and cages as well as feed them, and that is where he got his first opportunity to observe large anacondas killing and devouring their prey.

This early exposure to the captive reptiles inspired him to want to learn more about the way these creatures lived in the wild. When he later entered college at the Universidad Central de Venezuela he chose to study biology.

Dr. Rivas started the Anaconda Project in 1992. He had a number of sponsors. Dr. Rivas always believed that science should be conducted the old-fashioned way - out in the field.

To find the snakes, he waded-barefoot-in the knee-deep water of the Venezuelan llanos, the lowland savannah that is flooded each year during rainy season.

“The anaconda is the master of the swamp,” said Rivas. “Before 1992, no one knew anything about it, and you can’t really know anything about an animal by building computer models in the lab. You have to put on the shoes of the snake and wear them. That way you learn the difference between the truth and what you think the truth is.”

Dr. Rivas added, “My ultimate goal was to learn all the secrets of the life history of the animal and get a more firsthand knowledge of it. I have gathered eleven years

worth of data catching and processing more than 900 animals and with more than 170 recaptures.

I have followed with radio transmitter more than 38 animals, collected more than 100 diet samples, I have also found 51 breeding aggregations and studied the mating, pregnancy and delivery of more than 47 females. With the information gathered I hope to develop a management plan for the conservation of the species and the area in general”

As a result of his survey and research, some of the aspects of the giant snake’s lifestyle can now be told more accurately.

The Anaconda is in the boa family and the largest is the Eunectes family. The name Eunectes is derived from the Greek word which means “good swimmer.” The name seems to be derived from the South American Indian word combinations referencing elephant and killer. There are two possible origins for the common name “anaconda.”

The first is a Tamil word “anaikondran,” meaning “elephant killer.” A name first used in English to name a Ceylonese python, it erroneously was applied to a large South American boa, called in Brazil “sucuri”. Another suggestion is that it represents Tamil anaikkonda “having killed an elephant.”

It is unclear how this name originated so far from the snake’s native habitat; possibly this is due to its vague similarity to the large Asian pythons.

However, The Concise Oxford Dictionary of English Etymology, (1996) explains the word as follows : anaconda large S. American boa. (alt. of anacandaia (XVII) for Sinh. henakandaya whipsnake, f. hena lightning + kanda stem)

Water Boa

Like most snakes anaconda has suffered greatly from much exaggeration and scary folklore. Travellers’ diaries and notes often refer to 40 foot individuals and references to 140 foot monsters have actually been made, but likely never confirmed.

There is some debate about the maximum size of these snakes. Mehrtens (1987) states that the average adult length for the green anaconda, is 18 to 20 feet (5.5-6.1 m), with 25 feet (7.6 m) specimens being very rare.

He sets a more conservative maximum at 23 feet (7.0 m). In a study of 1,000 specimens captured in Venezuela, the largest was 17 feet (5.2 m) long and weighed 100 pounds (45 kg).

The anaconda is truly a constrictor! He usually utilises a swift bite to hold his prey (or victim), followed by a coiling of a loop or two around the main body.

Once these loops are in position, the snake will steadily constrict with incredible strength to suffocate the captive. It is the combination of sheer strength and unrelenting power that quickly replaces any breathing room. With each exhale of air, the lung slack is removed for any follow-up inhale! In moments, the prey is ready to consume. The larger specimens take on deer, pigs, cayman, fish, and larger prey.

Night Visitor

Of course, not all specimens are huge and each size gradient eats appropriately sized food, being able to swallow objects much larger in diameter than their own thickest section.

Simply holding a victim under water until drowning occurs is another less exciting but effective technique used by the anaconda in daily living.

Anacondas actually tend to be nocturnal which adds even more to the mystique on a dark still night! Due to their sometimes unwieldy size, they appear sluggish on land or hanging in a tree but in water they are capable of surprising speed on the surface and underneath.

Even with the huge size, they can stalk so stealthily that not a ripple is felt by a hapless victim until the water is churning as the killing grasp takes place! They often simply wait near the water on a tree limb and come raining down to catch animals as they come for necessary water.

As with all snakes, the suffocated victim is swallowed whole and in one piece. Primarily the head is swallowed first as the limbs tend to fold conveniently in and smoothly move down the rippling muscles as swallowing occurs, compressing the prey with each surge forward.

Very quickly, there is little outward evidence of a bump or object being present and a large proportionate meal may last for weeks.

Like all snakes, this species has a rather slow digestive tract and fortunately for the predator’s targets, hunting does not occur every day.

Anacondas are viviparous and thus give birth to live young. Sometimes as many as a hundred may be born but most often 20 to 30 babies around two feet in length are the result. Many fall prey to other predators in the food chain so that few will ever become the dominant top of the chain as adults.

Dr. Rivas currently teaches at Somerset Community College in Kentucky. He completed his Ph.D. at the University of Tennessee in 1999 based on his work with anacondas.

He is the author or co-author of several journal and popular articles, and maintains an informative website on anacondas at anacondas.org

Dr Rivas feels that there’s still a lot that is not known about anaconda that can only be learned from long-term studies conducted by continually tracking and observing them in their native habitat.

He is currently looking for adequate funds to continue research of this fascinating and enigmatic creature who, in full adulthood, is truly a natural wonder and is easily one of the most impressive creatures alive.