Post by Vodmeister on Sept 9, 2013 5:23:58 GMT 5
Black Caiman
The black caiman (Melanosuchus niger) is a large crocodilian and the biggest extant member of the family, Alligatoridae. It is a carnivorous reptile that lives along slow-moving rivers, lakes, seasonally flooded savannas of the Amazon basin, and in other freshwater habitats of South America. It is a quite large species, growing to sizes of at least 5 m (16 ft) and can weigh up to 400 kg (880 lb). On average though, an adult male black caiman will be around 3.6 m (12 ft) long and weigh 300 kg (660 lb). Several widely-reported but unconfirmed (and probably largely anecdotal) sources report that the black caiman can grow to over 6 m (20 ft) in length and weigh up to 1,100 kg (2,400 lb). As their name implies, the black caiman has a dark coloration, as an adult. In some individuals the dark coloration can appear almost black. However they have gray to brown banding on the lower jaw. Juveniles have a more vibrant coloration compared to adults with prominent white to pale yellow banding on the flanks that remains present well into adulthood, at least more when compared to other species. The morphology is quite different than other caimans but the bony ridge that occurs in other caimans is present. The head is large and heavy; an advantage in catching larger prey.
The black caiman is the largest predator in the Amazon ecosystem, preying on a variety of fish, reptiles, birds and mammals. They are generalists and an apex predator, potentially capable of taking any animal within its range, including other predators. Few ecological studies have been carried out on the species but it can be noted that the black caiman has its own ecological niche that enables coexistence without too much competition. As the largest predator in the ecosystem, it may also be a keystone species, playing an important role of maintaining the structure of the ecosystem. Reproduction takes place in the dry season. Females build a nest mound with an egg chamber, protecting the eggs from predators. Hatchlings form groups called pods, guarded by the presence of the female. These pods may contain individuals from other nests. Once common, it was hunted to near extinction primarily for its commercially valuable hide. It is now making a comeback, listed as Conservation Dependent. Overall, a little known species, it was not researched in any detail until the 1980s, when the leather-trade had already taken its toll. It is a dangerous species to humans and attacks have occurred in the past.
The black caiman has dark-colored, scaly skin. The skin coloration helps with camouflage during its nocturnal hunts, but may also help absorb heat (see thermoregulation). The lower jaw has grey banding (brown in older animals), and pale yellow or white bands are present across the flanks of the body, although these are much more prominent in juveniles. This banding fades only gradually as the animal matures. The bony ridge extending from above the eyes down the snout, as seen in other caiman, is present. The eyes are large, as befits its largely nocturnal activity, and brown in color. Mothers on guard near their nests are tormented by blood-sucking flies that gather around their vulnerable eyes leaving them bloodshot.
The black caiman is structurally dissimilar to other caiman species, particularly in the shape of the skull. Compared to other caimans, it has distinctly larger eyes. Although the snout is relatively narrow, the skull (given the species' considerably larger size) is much larger overall than other caimans. The greatest length of the skull can range to over 62 cm (24 in). Black caiman are relatively more robust than other crocodilians of comparable length. For example, a 3.9 m (13 ft) adult was found to have a considerably heavier and longer skull than a 4.8 m (16 ft) Nile crocodile (Crocodylus niloticus). Young black caiman can be distinguished from large spectacled caiman by their proportionately larger head and shorter tail, as well as by the color of the jaw, which is light colored in the Spectacled caiman and dark with three black spots in the black caiman.
Green Anaconda
The green anaconda (Eunectes murinus) 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 150 lb) in an average-range adult. It is the largest snake native to the Americas. Although it is not as long as the 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. Although the reticulated python is longer, the anaconda is the heaviest snake, with a 4.5m green anaconda having bulk comparable to a 7.4m reticulated python. 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.
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. 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.
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.
The black caiman (Melanosuchus niger) is a large crocodilian and the biggest extant member of the family, Alligatoridae. It is a carnivorous reptile that lives along slow-moving rivers, lakes, seasonally flooded savannas of the Amazon basin, and in other freshwater habitats of South America. It is a quite large species, growing to sizes of at least 5 m (16 ft) and can weigh up to 400 kg (880 lb). On average though, an adult male black caiman will be around 3.6 m (12 ft) long and weigh 300 kg (660 lb). Several widely-reported but unconfirmed (and probably largely anecdotal) sources report that the black caiman can grow to over 6 m (20 ft) in length and weigh up to 1,100 kg (2,400 lb). As their name implies, the black caiman has a dark coloration, as an adult. In some individuals the dark coloration can appear almost black. However they have gray to brown banding on the lower jaw. Juveniles have a more vibrant coloration compared to adults with prominent white to pale yellow banding on the flanks that remains present well into adulthood, at least more when compared to other species. The morphology is quite different than other caimans but the bony ridge that occurs in other caimans is present. The head is large and heavy; an advantage in catching larger prey.
The black caiman is the largest predator in the Amazon ecosystem, preying on a variety of fish, reptiles, birds and mammals. They are generalists and an apex predator, potentially capable of taking any animal within its range, including other predators. Few ecological studies have been carried out on the species but it can be noted that the black caiman has its own ecological niche that enables coexistence without too much competition. As the largest predator in the ecosystem, it may also be a keystone species, playing an important role of maintaining the structure of the ecosystem. Reproduction takes place in the dry season. Females build a nest mound with an egg chamber, protecting the eggs from predators. Hatchlings form groups called pods, guarded by the presence of the female. These pods may contain individuals from other nests. Once common, it was hunted to near extinction primarily for its commercially valuable hide. It is now making a comeback, listed as Conservation Dependent. Overall, a little known species, it was not researched in any detail until the 1980s, when the leather-trade had already taken its toll. It is a dangerous species to humans and attacks have occurred in the past.
The black caiman has dark-colored, scaly skin. The skin coloration helps with camouflage during its nocturnal hunts, but may also help absorb heat (see thermoregulation). The lower jaw has grey banding (brown in older animals), and pale yellow or white bands are present across the flanks of the body, although these are much more prominent in juveniles. This banding fades only gradually as the animal matures. The bony ridge extending from above the eyes down the snout, as seen in other caiman, is present. The eyes are large, as befits its largely nocturnal activity, and brown in color. Mothers on guard near their nests are tormented by blood-sucking flies that gather around their vulnerable eyes leaving them bloodshot.
The black caiman is structurally dissimilar to other caiman species, particularly in the shape of the skull. Compared to other caimans, it has distinctly larger eyes. Although the snout is relatively narrow, the skull (given the species' considerably larger size) is much larger overall than other caimans. The greatest length of the skull can range to over 62 cm (24 in). Black caiman are relatively more robust than other crocodilians of comparable length. For example, a 3.9 m (13 ft) adult was found to have a considerably heavier and longer skull than a 4.8 m (16 ft) Nile crocodile (Crocodylus niloticus). Young black caiman can be distinguished from large spectacled caiman by their proportionately larger head and shorter tail, as well as by the color of the jaw, which is light colored in the Spectacled caiman and dark with three black spots in the black caiman.
Green Anaconda
The green anaconda (Eunectes murinus) 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 150 lb) in an average-range adult. It is the largest snake native to the Americas. Although it is not as long as the 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. Although the reticulated python is longer, the anaconda is the heaviest snake, with a 4.5m green anaconda having bulk comparable to a 7.4m reticulated python. 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.
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. 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.
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.
