Anaconda

For other uses, see Anaconda (disambiguation).

Anaconda
Yellow Anaconda, Eunectes notaeus
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Squamata
Suborder:	Serpentes
Family:	Boidae
Genus:	Eunectes Wagler, 1830
Species
4, see article.

Anacondas (local name: Sucuri) are four species of aquatic boa inhabiting the swamps and rivers of the dense forests of tropical South America. The Yellow Anaconda can be found as far south as Argentina.

There are two possible origins for the word 'anaconda': It is perhaps an alteration of the Sinhalese word 'henakanday', meaning 'whip snake', or alternatively, the Tamil word 'anaikondran', which means 'elephant killer', as early Spanish settlers in South America referred to the anaconda as 'matatoro', or 'bull killer'. It is unclear how the name originated so far from the snake's native habitat; it is likely due to its vague similarity to the large Asian pythons.

Taxonomy and General Characteristics

Two species are well-known:

• The Green Anaconda (Eunectes murinus, from the Greek "ευνήκτης, eunectes", meaning "good swimmer"), which has been reliably reported in the 9 metre range (30 feet) in length (although most are considerably smaller). Although shorter than the longest recorded species, the Reticulated Python, it is considerably heavier. In fact, it is the heaviest snake species in existence: it can weigh 250 kg (551 pounds) and have a diameter of more than 30 cm (11.8 inches), but zoologist Johnathan Wright notes that average weight is about 126-150kg (about 275-330lbs), though specimens in captivity are generally smaller. Females average 6.7-7.9m (22-26ft) in length, while males average 3-4m (12-16ft). These are found mainly in northern South America, in Venezuela, Colombia, Brazil, Ecuador, northern Bolivia, Peru, Guyana, and the Nariva Swamp in Trinidad where they are known as "Huille" (pronounced Wheel).

Green Anaconda, Eunectes murinus

File:Anacondatree.jpg

A wild anaconda snake, Amazon basin, Peru.

File:Anacondatree2.jpg

An anaconda snake on a tree branch, waiting for its prey above the river, Amazon basin, Peru.

Anaconda at the Reptile Zoo east of Monroe, Washington.

• The Yellow Anaconda (Eunectes notaeus), which reaches a relatively smaller average adult length of 3 metres (9.8 feet). These live further south in Bolivia, Paraguay, Uruguay, western Brazil, and northeast Argentina.

The two lesser-known species are:

• The Dark-Spotted or Deschauense's Anaconda (Eunectes deschauenseei) found in northeast Brazil.
• The Bolivian Anaconda (Eunectes beniensis) found in Bolivia, which was only identified in 2002 by Lutz Dirksen, and is still being studied.

Eunectes murinus (formerly called Boa murina) differs from Boa by the snout being covered with shields instead of small scales, the inner of the three nasal shields being in contact with that of the other side. The general colour is dark olive-brown, with large oval black spots arranged in two alternating rows along the back, and with smaller white-eyed spots along the sides. The belly is whitish, spotted with black spots. The anaconda combines an arboreal with an aquatic life and is active mostly during the night. It lies submerged in the water, with only a small part of its head above the surface, waiting for any suitable prey, or it establishes itself upon the branches of a tree which overhangs the water or the track of game.

The anaconda has 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 lies submerged under water. The extremely muscular anaconda is a constrictor and is not venomous; 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. The anaconda has a cavity called a cloaca which is where the intestinal and genito-urinary tracts empty, with spurs on either side of the cloaca, and a gland which emits a foul-smelling musk.

Despite the hold they have on the imagination, relatively little information was known about the anacondas until 1992 when the first study was made on the field biology of this species in the Venezuelan llanos by Dr. Jesus Rivas. They typically feed on large rodents, tapirs, capybaras, deer, peccaries, fish, turtles, birds, sheep, dogs, and aquatic reptiles like caiman. 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. 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. They themselves are preyed by jaguars, large caimans and by other anacondas. A wounded anaconda can also fall prey to piranhas.

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 asphyxiated 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 breathe in again. Suffocation does not take long. Anacondas swallow their prey whole, starting with the head. This is so that 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 jaw bones are loosely connected to the skull. While the snake eats, its muscles have wave-like contractions, crushing the prey even further and forcing it downward with each bite.

Just about every species of snake on earth has teeth, but the anacondas' teeth are not used for chewing. Most snakes' teeth are used for holding onto their prey, preventing them from escaping. Some snakes have venom in two specially designed, extra long teeth which they use to kill their prey. Anacondas do have teeth, but their bites are neither fatal nor venomous. They rely on their enormous size and power to subdue their victims. It is possible to be bitten by an anaconda, but the bite itself would not be fatal. Like almost all boas, anacondas give birth to live young.

Giant Anacondas

There is some debate about the maximum size of anacondas, and there have been unverified claims of enormous snakes alleged to be even much larger.

According to Lee Krystek , a 1944 petroleum expedition in Colombia claimed to have measured an 11.4m (37.5ft) specimen, but this claim is not always regarded as reliable; perhaps a more credible report came from scientist Vincent Roth, who claimed to have shot and killed a 10.3m (34ft) anaconda in British Guiana.

There are some reports from early European explorers of the South American jungles seeing giant anacondas up to 18.2m (60ft) long and some of the native peoples of the South American jungle have reported seeing anacondas up to 15.2m (50ft) long., but these examples are not verified, and are often regarded as exaggerated.

Another claim of extraordinary anaconda size was reported by adventurer Percy Fawcett. During a 1906 expedition, Fawcett wrote that he had shot and wounded an anaconda in South America; he reported the snake measured some 18.9m (62 ft) from nose to tail. Once publicized, Fawcett’s account of the giant snake was widely ridiculed, although he insisted his account was both truthful and accurate. Decades later, Belgian zoologist Bernard Heuvelmans came to Fawcett's defense, arguing that Fawcett's writing was generally honest and reliable. Furthermore, Heuvelmans noted that mainstream experts were repeatedly forced to revise their limits regarding the maximum size of snakes when confronted with specimens that defied the generally-accepted estimates: at one point 6 metres (20 feet) in length was the widely-accepted maximum size of an anaconda, but during Heuvelmans' life, figures in the 9m (30ft) range were accepted as plausible.

Historian Mike Dash writes of claims of still larger anacondas, alleged to be as long as 30-45m (100-150ft) -- some of which are evidenced with photos, all of which lack any sense of scale; Dash notes that if a 50-60ft anaconda strains credulity, then a 150ft long specimen is generally regarded as an outright impossibility.

In captivity

Anacondas have a reputation for bad temperament; that plus the massive size of the green species mean that anacondas are comparatively less popular as pets than other boas, but they are fairly commonly available in the exotic pet trade.

In movies

• In Swiss Family Robinson, Fritz and Ernst have a run-in with an Anaconda.

• In the movies Anaconda and its sequel Anacondas: The Hunt for the Blood Orchid the anaconda has the role of a giant man-eating snake. In the first film the anaconda is shown at an exceptionally exaggerated length and girth, clearly far larger than actual anacondas in the wild get. The second movie takes fiction to a new level by placing the anaconda at Borneo, and making it a 'super snake', growing up to 21 metres long, supposedly because of the blood orchid. Anacondas on average grow up to 6 metres, but have been rumored to reach 12 metres.

• In Jackass: Number Two, Johnny Knoxville, Ryan Dunn, and Wee Man crawl around in a ball pit, trying to catch two anacondas that were let loose in the pit. Knoxville is bitten several times in the arms.

• The Discovery Channel series Animal Face-Off featured an episode wherein an Anaconda was pitted against a Jaguar in a computer simulation to determine which animal would win a battle between the two.

• ADW: Eunectes murinus (green anaconda)
• Infectious disease serologic survey in free-ranging Venezuelan anacondas.

References

• Bernard Heuvelmans (1958). On the Track of Unknown Animals. Hill and Wang. ISBN 0710304986.

External links

• Man frees grandson from anaconda death grip