The Life of Animals | Polar Bears | Polar bears or polar bear or the scientific name Ursus maritimus is the rule genera of large mammals, biological family Ursidae. He included Circumpolar species contained in and around the Arctic and is the largest land mammal genera of animals. Polar bears adult males weighing between 400 to 600 kilograms and occasionally exceed 800 kg. Polar bears about half the weight of female and male bears typically weigh between 200 to 300 kg. Adult male bears along the 240 to 260 centimeters and the female polar bears between 190 to 210 cm. When a newborn, baby bear weighing 600 to 700 grams.
In winter, the bears more than a slow metabolism can be predicted by their body temperature. Do not judge a bear of body temperature, such as indicated by the first data about the physiology of hibernation. There's something going on in the black bear hibernation which slows metabolism ratio is more than can be explained by a low body temperature, according to a report Oivind Toien ecological physiologists from the University of Alaska Fairbanks. In the winter of Alaska, the black bears are closely monitored, lowering their body temperature an average of only 5.5 degrees Celsius, as reported by Tøien and his colleagues in the February 18 issue of the journal Science. Physiology standard calculations predict that the cold as it will slow the metabolism of about 65 percent ratio non hibernasi break. However, metabolism is slowed even the bears to the zone of energy savings that on average only 25 percent of the basic ratio of the summer.
Things like that have so far not been found in studies on other mammals that do hibernate, said co-researcher Brian M. Barnes is also from the University of Alaska Fairbanks. Mammalian hibernation is important for human medical research, said Hank Harlow ecological physiologists from the University of Wyoming in Laramie. Basing on the mechanism that eager to be understood by scientists, black bears spend five to seven months without eating, drinking or urinating. However, unlike people who simply spend some time in bed or outer space, mammals that hibernate do not lose muscle strength or their bone mass. "The bear is impressive," said Harlow.
This study is the first continuously monitors the ratio of metabolism and body temperature during hibernation bears on the conditions of low disturbance, said Tøien. Another study based on sampling is not continuous with the older equipment, indirect evidence, or studying the bears with a lot of people who are in close proximity, resulting in "uncertainty," he said. He and his colleagues get the data in such a big way to volunteer for the study of black bears searching for food near the residential area and will soon be killed because it was considered as a threat. "We read about them in the Anchorage Daily News before we get them," said Toien.
To study their hibernation, the researchers monitored the five bears, putting them in wooden boxes deep in the woods. Wooden boxes are deliberately not very strong so that the bears can destroy it whenever they want to get out. But when the bears are in it, the researchers examined the concentration of oxygen to track the metabolic ratio. The instruments also measured the movement of muscle and heart function. One of the bears are not much lower body temperatures during early hibernation until she gave birth to a cub. The child bears can not survive, and after that the female bear's body temperature is behaving more like a body other bears.
Reports of decreased metabolic ratio is good enough for hibernation encouraging Eric Hellgren from Northern Illinois University, which recognizes "a biased point of view as a bear biologist." He said studies conducted in Alaska may be an end to a lengthy discussion of the physiologists who consider hibernation bears as "a form different and 'less'" than the major metabolic changes seen in small animals like ground squirrels. More detailed monitoring also reveals a special bear habits, such as the cycles of several days or during mid-hibernation when the bears to temporarily raise their body temperature. Tøien not assess a small increase is equivalent to the full periodic heating is usually done by almost all the smaller animals that do hibernate, which raise their body temperature to the normal range for several weeks, urinate and then dropping their body temperature. The researchers are not careful measuring metabolism during a bear cycle will get inflation numbers on the line hibernation, he noted.
Measurement of heart rate on the three bears of Alaska shows a decrease from an average of 55 beats per minute before hibernation to 14 beats per minute erratic season. Harlow said he had also heard of bears hibernating heart beats for some time and then beat the erratic. Perhaps to save energy, speculation. Alaska team also found that when the bears move again in the spring, their metabolism takes several weeks to crawl back to normal. Monitoring data indicate that the bears with half the speed of metabolic ratio still showed a normal bear behavior. Observations are compatible with studies conducted on grizzly bears that spend the first few weeks after hibernation with half a heart rate of speed in the summer, said Lynne Nelson of Washington State University in Pullman. "The ability of physiological adaptation of the system bears this never stops surprising me."
