Post by DinosaurMichael on Jun 23, 2012 6:22:20 GMT -5
Giant Otter - Pteronura brasiliensis
The giant otter (Pteronura brasiliensis) is a South American carnivorous mammal. It is the longest member of the Mustelidae, or weasel family, a globally successful group of predators. Unusual for a mustelid, the giant otter is a social species, with family groups typically supporting three to eight members. The groups are centered on a dominant breeding pair and are extremely cohesive and cooperative. Although generally peaceful, the species is territorial, and aggression has been observed between groups. The giant otter is diurnal, being active exclusively during daylight hours. It is the noisiest otter species, and distinct vocalizations have been documented that indicate alarm, aggressiveness, and reassurance. The giant otter ranges across north-central South America; it lives mostly in and along the Amazon River and in the Pantanal. Its distribution has been greatly reduced and is now discontinuous. Decades of poaching for its velvety pelt, peaking in the 1950s and 1960s, hugely diminished population numbers. The species was listed as endangered in 1999 and wild population estimates are typically below 5,000. The Guianas are one of the last real strongholds for the species, which also enjoys modest numbers - and significant protection - in the Peruvian Amazonian basin. It is one of the most endangered mammal species in the neotropics. Habitat degradation and loss is the greatest current threat. The giant otter is also rare in captivity; in 2003, only 60 animals were being held. The giant otter shows a variety of adaptations suitable to an amphibious lifestyle, including exceptionally dense fur, a wing-like tail, and webbed feet. The species prefers freshwater rivers and streams, which are usually seasonally flooded, and may also take to freshwater lakes and springs. It constructs extensive campsites close to feeding areas, clearing large amounts of vegetation. The giant otter largely subsists on a diet of fish, particularly characins and catfish, and may also eat crabs. It has no serious natural predators other than humans, although it must compete with other species, including the neotropical otter and caiman species, for food resources. The giant otter has a handful of other names. River wolf (Spanish: lobo de río) and water dog (Spanish: perro de agua) are used occasionally, though the latter has many other meanings) and may have been more common in the reports of explorers in the 19th and early 20th centuries. All three names are in use in Spanish and Portuguese, with a number of regional variations. "Giant otter" translates as nutria gigante and lontra gigante in Spanish and Portuguese, respectively; a fourth name, ariraí or ariranha is also in use in South America. Among the Achuar people, they are known as wankanim, and among the Sanumá as hadami. The genus name, Pteronura, is derived from the Ancient Greek words pteron/πτερον (feather or wing) and ura/ουρά (tail), a reference to its distinctive, wing-like tail. The giant otter is large, gregarious, and diurnal (active through the day). Early travellers' reports describe noisy groups surrounding explorers' boats, but little scientific information was available on the species until Duplaix's groundbreaking work in the late 1970s. Concern over this endangered species has since generated a body of research. The giant otter is clearly distinguished from other otters by morphological and behavioral characteristics. It has the greatest body length of any species in the mustelid family, although the sea otter may be heavier. Males are between 1.5 and 1.7 m (4.9 and 5.6 ft) in length from head to tail and females between 1 and 1.5 m (3.3 and 4.9 ft). The animal's well-muscled tail can add a further 70 cm (28 in) to the total body length. Early reports of skins and living animals suggested exceptionally large males of up to 2.4 m (7.9 ft); intensive hunting likely reduced the occurrence of such massive specimens. Weights are between 26 and 32 kg (57 and 71 lb) for males and 22 and 26 kg (49 and 57 lb) for females. The giant otter has the shortest fur of all otter species; it is typically chocolate brown, but may be reddish or fawn, and appears nearly black when wet. The fur is extremely dense, so much so that water cannot penetrate to the skin. Guard hairs trap water and keep the inner fur dry; the guard hairs are approximately 8 millimeters (one-third of an inch) in length, about twice as long as the fur of the inner coat. Its velvety feel makes the animal highly sought after by fur traders and has contributed to its decline. Unique markings of white or cream fur color the throat and under the chin, allow individuals to be identified from birth. Giant otters use these marks to recognize one another, and upon meeting other otters, they engage in a behavior known as "periscoping", displaying their throats and upper chests to each other. Giant otter muzzles are short and sloping and give the head a ball-shaped appearance. The ears are small and rounded. The nose (or rhinarium) is completely covered in fur, with only the two slit-like nostrils visible. The giant otter's highly sensitive whiskers (vibrissae) allow the animal to track changes in water pressure and currents, which aids in detecting prey. The legs are short and stubby and end in large webbed feet tipped with sharp claws. Well suited for an aquatic life, it can close its ears and nose while underwater. At the time of Carter and Rosas' writing, vision had not been directly studied, but field observations show the animal primarily hunts by sight; above water, it is able to recognize observers at great distances. The fact that it is exclusively active during the day further suggests its eyesight should be strong, to aid in hunting and predator avoidance. In other otter species, vision is generally normal or slightly myopic, both on land and in water. The giant otter's hearing is acute and its sense of smell excellent.
Spectacled Caiman - Caiman crocodilus
The spectacled caiman (Caiman crocodilus), also known as the white caiman or common caiman, is a crocodilian reptile found in much of Central and South America. It lives in a range of lowland wetland and riverine habitat types and can tolerate salt water as well as fresh; due in part to this adaptability it is the most common of all crocodilian species. Males of the species are generally 2 to 2.5 metres (6.6 to 8.2 ft), while females are smaller, usually around 1.4 metres (4.6 ft). They mainly weigh up to 40 kg (88 lbs). The species' common name comes from a bony ridge between the eyes, which gives the appearance of a pair of spectacles. They have been known to change color. During colder weather the black pigment, found within their skin cells, will expand making them darker.
The giant otter (Pteronura brasiliensis) is a South American carnivorous mammal. It is the longest member of the Mustelidae, or weasel family, a globally successful group of predators. Unusual for a mustelid, the giant otter is a social species, with family groups typically supporting three to eight members. The groups are centered on a dominant breeding pair and are extremely cohesive and cooperative. Although generally peaceful, the species is territorial, and aggression has been observed between groups. The giant otter is diurnal, being active exclusively during daylight hours. It is the noisiest otter species, and distinct vocalizations have been documented that indicate alarm, aggressiveness, and reassurance. The giant otter ranges across north-central South America; it lives mostly in and along the Amazon River and in the Pantanal. Its distribution has been greatly reduced and is now discontinuous. Decades of poaching for its velvety pelt, peaking in the 1950s and 1960s, hugely diminished population numbers. The species was listed as endangered in 1999 and wild population estimates are typically below 5,000. The Guianas are one of the last real strongholds for the species, which also enjoys modest numbers - and significant protection - in the Peruvian Amazonian basin. It is one of the most endangered mammal species in the neotropics. Habitat degradation and loss is the greatest current threat. The giant otter is also rare in captivity; in 2003, only 60 animals were being held. The giant otter shows a variety of adaptations suitable to an amphibious lifestyle, including exceptionally dense fur, a wing-like tail, and webbed feet. The species prefers freshwater rivers and streams, which are usually seasonally flooded, and may also take to freshwater lakes and springs. It constructs extensive campsites close to feeding areas, clearing large amounts of vegetation. The giant otter largely subsists on a diet of fish, particularly characins and catfish, and may also eat crabs. It has no serious natural predators other than humans, although it must compete with other species, including the neotropical otter and caiman species, for food resources. The giant otter has a handful of other names. River wolf (Spanish: lobo de río) and water dog (Spanish: perro de agua) are used occasionally, though the latter has many other meanings) and may have been more common in the reports of explorers in the 19th and early 20th centuries. All three names are in use in Spanish and Portuguese, with a number of regional variations. "Giant otter" translates as nutria gigante and lontra gigante in Spanish and Portuguese, respectively; a fourth name, ariraí or ariranha is also in use in South America. Among the Achuar people, they are known as wankanim, and among the Sanumá as hadami. The genus name, Pteronura, is derived from the Ancient Greek words pteron/πτερον (feather or wing) and ura/ουρά (tail), a reference to its distinctive, wing-like tail. The giant otter is large, gregarious, and diurnal (active through the day). Early travellers' reports describe noisy groups surrounding explorers' boats, but little scientific information was available on the species until Duplaix's groundbreaking work in the late 1970s. Concern over this endangered species has since generated a body of research. The giant otter is clearly distinguished from other otters by morphological and behavioral characteristics. It has the greatest body length of any species in the mustelid family, although the sea otter may be heavier. Males are between 1.5 and 1.7 m (4.9 and 5.6 ft) in length from head to tail and females between 1 and 1.5 m (3.3 and 4.9 ft). The animal's well-muscled tail can add a further 70 cm (28 in) to the total body length. Early reports of skins and living animals suggested exceptionally large males of up to 2.4 m (7.9 ft); intensive hunting likely reduced the occurrence of such massive specimens. Weights are between 26 and 32 kg (57 and 71 lb) for males and 22 and 26 kg (49 and 57 lb) for females. The giant otter has the shortest fur of all otter species; it is typically chocolate brown, but may be reddish or fawn, and appears nearly black when wet. The fur is extremely dense, so much so that water cannot penetrate to the skin. Guard hairs trap water and keep the inner fur dry; the guard hairs are approximately 8 millimeters (one-third of an inch) in length, about twice as long as the fur of the inner coat. Its velvety feel makes the animal highly sought after by fur traders and has contributed to its decline. Unique markings of white or cream fur color the throat and under the chin, allow individuals to be identified from birth. Giant otters use these marks to recognize one another, and upon meeting other otters, they engage in a behavior known as "periscoping", displaying their throats and upper chests to each other. Giant otter muzzles are short and sloping and give the head a ball-shaped appearance. The ears are small and rounded. The nose (or rhinarium) is completely covered in fur, with only the two slit-like nostrils visible. The giant otter's highly sensitive whiskers (vibrissae) allow the animal to track changes in water pressure and currents, which aids in detecting prey. The legs are short and stubby and end in large webbed feet tipped with sharp claws. Well suited for an aquatic life, it can close its ears and nose while underwater. At the time of Carter and Rosas' writing, vision had not been directly studied, but field observations show the animal primarily hunts by sight; above water, it is able to recognize observers at great distances. The fact that it is exclusively active during the day further suggests its eyesight should be strong, to aid in hunting and predator avoidance. In other otter species, vision is generally normal or slightly myopic, both on land and in water. The giant otter's hearing is acute and its sense of smell excellent.
Spectacled Caiman - Caiman crocodilus
The spectacled caiman (Caiman crocodilus), also known as the white caiman or common caiman, is a crocodilian reptile found in much of Central and South America. It lives in a range of lowland wetland and riverine habitat types and can tolerate salt water as well as fresh; due in part to this adaptability it is the most common of all crocodilian species. Males of the species are generally 2 to 2.5 metres (6.6 to 8.2 ft), while females are smaller, usually around 1.4 metres (4.6 ft). They mainly weigh up to 40 kg (88 lbs). The species' common name comes from a bony ridge between the eyes, which gives the appearance of a pair of spectacles. They have been known to change color. During colder weather the black pigment, found within their skin cells, will expand making them darker.
