Post by Vodmeister on Mar 27, 2014 13:03:35 GMT 5
Eunectes murinus
Eunectes murinus (derived from the Greek
?? meaning "good swimmer" and the Latin murinus meaning "of mice" for being thought to prey on mice), commonly known as the green anaconda, is a non-venomous boa species found in South America. It is the largest, heaviest, and second longest (behind the reticulated python) known extant snake species. The term anaconda (without further qualification) often refers to this species, though the term could also apply to other members of the genus Eunectes. Other common names include common anaconda and water boa.
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Boidae
Subfamily: Boinae
Genus: Eunectes
Species: E. murinus
Physical Description
The green anaconda is the world's heaviest and one of the world's longest snakes, reaching more than 6.6 m (22 ft) long. More typical mature specimens reportedly can range up 5 m (16 ft), with the females, at around a mean length of 4.6 m (15 ft), being generally much larger in adulthood than the male, which averages around 3 m (9.8 ft). Weights are less well studied, though will reportedly range from 30 to 70 kg (66 to 154 lb) in an average-range adult. It is the largest snake native to the Americas. Although it is slightly shorter than the Reticulated python, it is far more robust: the bulk of a 4.5m green anaconda is comparable to a 7.4m reticulated python. Eucentes murinus is probably the heaviest extant species of snake or squamate in the world, perhaps only rivaled by the Komodo dragon. Reports of anacondas 35–40 feet or even longer also exist, but such claims need to be regarded with caution, as no specimens of such lengths have ever been deposited in a museum and hard evidence is lacking. A $50,000 cash reward is offered for anyone who can catch an anaconda 30 ft (9.1 m) or longer, but the prize has not been claimed yet. The longest (and heaviest) scientifically verified specimen was a female measuring 521 cm (17.09 ft) long and weighing 97.5 kg (215 lb).
The color pattern consists of olive green background overlaid with black blotches along the length of the body. The head is narrow compared to the body, usually with distinctive orange-yellow striping on either side. The eyes are set high on the head, allowing the snake to see out of the water while swimming without exposing its body.
Difficulties in determining maximum size
The remote location of the snake's habitat has historically made locating, capturing, and returning specimens difficult. Transporting very large specimens to museums, especially before substantial decay, is difficult (though this has not prevented the return of much larger and more cumbersome crocodilian specimens). Skins can stretch substantially, increasing the snake's size by more than 50% if stretched during the tanning process. Reports without physical proof are considered dubious if from nonscientists, as such individuals may at worst be more interested in promoting themselves or telling a good tale, or at the least may not be sufficiently trained in proper measurement methods. Observational reports of animals which were not captured are even more dubious, as even trained scientists often substantially overestimate the size of anacondas prior to capture. According to the Guinness Book of World Records, this species has been perhaps subject to the most extreme size exaggerations of any living animal.[9] At the same time, it is difficult to argue a maximum possible or plausible size, because anacondas are known to continue to grow throughout their lives. Older reports in particular could include individuals which, in times of less pressure from humans, lived longer lives and thus reached greater sizes.
Historical records
Numerous historical accounts of green anacondas are reported, often of ridiculously improbable sizes. Several zoologists (notably Henry Walter Bates and Alfred Russel Wallace, among others) note rumors of snakes beyond 30 or 40 feet long, but in each case, their direct observations were limited to snakes of approximately 20 feet in length. Numerous estimates and second-hand accounts abound, but are generally considered unreliable. To prove the point of overestimating, in Guyana in 1937, zoologist Alpheus Hyatt Verrill asked the expedition team he was with to estimate the length of a large, curled-up anaconda on a rock. The team's guesses ran from 6.1 to 18.3 m (20 to 60 ft); when measured, this specimen was found to be 5.9 m (19 ft). Almost all specimens in excess of 6 m (20 ft), including a much publicized specimen of 11.36 m (37.3 ft) in length, have no voucher specimens, including skins or bones. The skin of one specimen, stretched to 10 m (33 ft), has been preserved in the Instituto Butantan in São Paulo and is reported to have come from an anaconda of 7.6 m (25 ft) in length. In one of the most reliable accounts, a geologist killed a large anaconda and measured it using a four-meter rod, reporting it as three rods long (12 m (39 ft)); however, the information was not published until many years later, and the geologist later suggested he may have misremembered and the anaconda could have been only two rods long (8 m (26 ft)). While in Colombia in 1978, herpetologist William W. Lamar had an encounter with a large female specimen which measured 7.5 m (25 ft) and was estimated to weigh between 136 and 180 kg (300 and 397 lb). In 1962, W.L. Schurz claimed to have measured a snake in Brazil of 8.46 m (27.8 ft) with a maximum girth of 112 cm (3.67 ft). One female, reportedly measuring 7.9 m (26 ft) in length, shot in 1963 in Nariva Swamp, Trinidad, contained a 1.5-m caiman. A specimen of 7.3 m (24 ft), reportedly with a weight of 149 kg (328 lb), was caught at the mouth of the Kassikaityu River in Guyana, having been restrained by 13 local men, and was later air-lifted for a zoo collection in the United States, but died in ill health shortly thereafter. The largest size verified for E. murinus in captivity was for a specimen kept in Pittsburgh Zoo and PPG Aquarium, which grew to a length of 6.27 m (20.6 ft) by the time she died on July 20, 1960. When this specimen was 5.94 m (19.5 ft) long, she weighed 91 kg (201 lb). The estimated weight for an anaconda in the range of 8 m (26 ft) is at least 200 kg (440 lb). National Geographic has published a weight of up to 227 kg (500 lb) for E. murinus, but this is almost certainly a mere estimation. Weight can vary considerably in large specimens depending on environmental conditions and recent feedings, with Verrill's aforementioned specimen, having been extremely bulky, scaled at 163 kg (359 lb), whereas another specimen considered large at 5.06 m (16.6 ft), weighed only 54 kg (119 lb).
Current estimates of maximal size
Size presents challenges to attain breeding condition in larger female anacondas and while larger sizes provide the benefit of larger number of offspring per clutch, the breeding frequency of the individuals reduces with size, indicating that there's a point in which the advantage of larger clutch size is negated by the female no longer being able to breed, for the anaconda, this limit was estimated at approximately 6.7 m (22 ft) in total length. This is consistent with the results of a revision of the size at maturity and maximum size of several snakes from North America, which found that the maximum size is between 1.5 and 2.5 the size at maturity. The minimum size of breeding anacondas in a survey of 780 individuals was 2.1 m (6.9 ft) in snout-vent length, indicating that maximum size attained by anacondas following this pattern would be 5.3 m (17 ft) in snout-vent length. However, most anacondas are captured from the llanos, which is more accessible to humans and has smaller prey available, while the rainforest, which is much less explored and has more plentiful large prey, may be home to larger snakes.
en.wikipedia.org/wiki/Eunectes_murinus
Eunectes murinus (derived from the Greek
?? meaning "good swimmer" and the Latin murinus meaning "of mice" for being thought to prey on mice), commonly known as the green anaconda, is a non-venomous boa species found in South America. It is the largest, heaviest, and second longest (behind the reticulated python) known extant snake species. The term anaconda (without further qualification) often refers to this species, though the term could also apply to other members of the genus Eunectes. Other common names include common anaconda and water boa.Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Boidae
Subfamily: Boinae
Genus: Eunectes
Species: E. murinus
Physical Description
The green anaconda is the world's heaviest and one of the world's longest snakes, reaching more than 6.6 m (22 ft) long. More typical mature specimens reportedly can range up 5 m (16 ft), with the females, at around a mean length of 4.6 m (15 ft), being generally much larger in adulthood than the male, which averages around 3 m (9.8 ft). Weights are less well studied, though will reportedly range from 30 to 70 kg (66 to 154 lb) in an average-range adult. It is the largest snake native to the Americas. Although it is slightly shorter than the Reticulated python, it is far more robust: the bulk of a 4.5m green anaconda is comparable to a 7.4m reticulated python. Eucentes murinus is probably the heaviest extant species of snake or squamate in the world, perhaps only rivaled by the Komodo dragon. Reports of anacondas 35–40 feet or even longer also exist, but such claims need to be regarded with caution, as no specimens of such lengths have ever been deposited in a museum and hard evidence is lacking. A $50,000 cash reward is offered for anyone who can catch an anaconda 30 ft (9.1 m) or longer, but the prize has not been claimed yet. The longest (and heaviest) scientifically verified specimen was a female measuring 521 cm (17.09 ft) long and weighing 97.5 kg (215 lb).
The color pattern consists of olive green background overlaid with black blotches along the length of the body. The head is narrow compared to the body, usually with distinctive orange-yellow striping on either side. The eyes are set high on the head, allowing the snake to see out of the water while swimming without exposing its body.
Difficulties in determining maximum size
The remote location of the snake's habitat has historically made locating, capturing, and returning specimens difficult. Transporting very large specimens to museums, especially before substantial decay, is difficult (though this has not prevented the return of much larger and more cumbersome crocodilian specimens). Skins can stretch substantially, increasing the snake's size by more than 50% if stretched during the tanning process. Reports without physical proof are considered dubious if from nonscientists, as such individuals may at worst be more interested in promoting themselves or telling a good tale, or at the least may not be sufficiently trained in proper measurement methods. Observational reports of animals which were not captured are even more dubious, as even trained scientists often substantially overestimate the size of anacondas prior to capture. According to the Guinness Book of World Records, this species has been perhaps subject to the most extreme size exaggerations of any living animal.[9] At the same time, it is difficult to argue a maximum possible or plausible size, because anacondas are known to continue to grow throughout their lives. Older reports in particular could include individuals which, in times of less pressure from humans, lived longer lives and thus reached greater sizes.
Historical records
Numerous historical accounts of green anacondas are reported, often of ridiculously improbable sizes. Several zoologists (notably Henry Walter Bates and Alfred Russel Wallace, among others) note rumors of snakes beyond 30 or 40 feet long, but in each case, their direct observations were limited to snakes of approximately 20 feet in length. Numerous estimates and second-hand accounts abound, but are generally considered unreliable. To prove the point of overestimating, in Guyana in 1937, zoologist Alpheus Hyatt Verrill asked the expedition team he was with to estimate the length of a large, curled-up anaconda on a rock. The team's guesses ran from 6.1 to 18.3 m (20 to 60 ft); when measured, this specimen was found to be 5.9 m (19 ft). Almost all specimens in excess of 6 m (20 ft), including a much publicized specimen of 11.36 m (37.3 ft) in length, have no voucher specimens, including skins or bones. The skin of one specimen, stretched to 10 m (33 ft), has been preserved in the Instituto Butantan in São Paulo and is reported to have come from an anaconda of 7.6 m (25 ft) in length. In one of the most reliable accounts, a geologist killed a large anaconda and measured it using a four-meter rod, reporting it as three rods long (12 m (39 ft)); however, the information was not published until many years later, and the geologist later suggested he may have misremembered and the anaconda could have been only two rods long (8 m (26 ft)). While in Colombia in 1978, herpetologist William W. Lamar had an encounter with a large female specimen which measured 7.5 m (25 ft) and was estimated to weigh between 136 and 180 kg (300 and 397 lb). In 1962, W.L. Schurz claimed to have measured a snake in Brazil of 8.46 m (27.8 ft) with a maximum girth of 112 cm (3.67 ft). One female, reportedly measuring 7.9 m (26 ft) in length, shot in 1963 in Nariva Swamp, Trinidad, contained a 1.5-m caiman. A specimen of 7.3 m (24 ft), reportedly with a weight of 149 kg (328 lb), was caught at the mouth of the Kassikaityu River in Guyana, having been restrained by 13 local men, and was later air-lifted for a zoo collection in the United States, but died in ill health shortly thereafter. The largest size verified for E. murinus in captivity was for a specimen kept in Pittsburgh Zoo and PPG Aquarium, which grew to a length of 6.27 m (20.6 ft) by the time she died on July 20, 1960. When this specimen was 5.94 m (19.5 ft) long, she weighed 91 kg (201 lb). The estimated weight for an anaconda in the range of 8 m (26 ft) is at least 200 kg (440 lb). National Geographic has published a weight of up to 227 kg (500 lb) for E. murinus, but this is almost certainly a mere estimation. Weight can vary considerably in large specimens depending on environmental conditions and recent feedings, with Verrill's aforementioned specimen, having been extremely bulky, scaled at 163 kg (359 lb), whereas another specimen considered large at 5.06 m (16.6 ft), weighed only 54 kg (119 lb).
Current estimates of maximal size
Size presents challenges to attain breeding condition in larger female anacondas and while larger sizes provide the benefit of larger number of offspring per clutch, the breeding frequency of the individuals reduces with size, indicating that there's a point in which the advantage of larger clutch size is negated by the female no longer being able to breed, for the anaconda, this limit was estimated at approximately 6.7 m (22 ft) in total length. This is consistent with the results of a revision of the size at maturity and maximum size of several snakes from North America, which found that the maximum size is between 1.5 and 2.5 the size at maturity. The minimum size of breeding anacondas in a survey of 780 individuals was 2.1 m (6.9 ft) in snout-vent length, indicating that maximum size attained by anacondas following this pattern would be 5.3 m (17 ft) in snout-vent length. However, most anacondas are captured from the llanos, which is more accessible to humans and has smaller prey available, while the rainforest, which is much less explored and has more plentiful large prey, may be home to larger snakes.
en.wikipedia.org/wiki/Eunectes_murinus
