Mais FAQ do Urso Polaris

Frequently Asked Questions about polar bears

1. What does the Latin name "Ursus maritimus" mean?
2. How many species of bears are there besides polar bears and where do they live?
3. How many polar bears are there in the world?
4. How far south can we meet polar bears – and how far north?
5. How large do polar bears get?
6. What is the basics of polar bear life history?
7. What do they eat?
8. Some say that polar bear fur have fiber-optic qualities. Is this true?
9. What is trichinosis?
10. How are they adapted to a cold and wet environment as the Arctic?
11. Why are there no polar bears in Antarctica?
12. How far can they swim and for how long can they hold their breath?
13. How fast can they run?
14. How many polar bears are hunted, and where?

1 - What does the Latin name "Ursus maritimus" mean?

The name Ursus maritimus is Latin - "Ursus" means "bear" and "maritimus" means "sea". Thus "Ursus maritimus" can be translated into "bear of the sea".


2 - How many species of bears are there besides polar bears and where do they live?

There are 8 species of bears around the world:


BEAR SPECIES LATIN NAME DISTRIBUTION

Polar bear Ursus maritimus Arctic circumpolar

Sun bear Ursus malayanus Previously the entire southeast Asia, but today mostly in Indonesia and Malaysia, are now believed to be extinct in India and possibly Bangladesh.

Sloth bear Ursus ursinus Found in forests and grasslands in India, Sri Lanka, Bangladesh, Nepal and Bhutan.

Brown bear Ursus arctos North America and Eurasia, including Japan and former Soviet territories. The North-American brown bear is also called "Grizzly".

Black bear Ursus americanus North America

Spectacled bear Tremarctos ornatus South America, mostly within national parks in the Andes region, from Venezuela and Colombia southwards through Ecuador, Peru and Bolivia.

Asiatic black bear Ursus thibetanus Currently distributed in two large areas, one in southeast Asia, extending from Malaysia through The Himalayas as far as Pakistan, Iran and Iraq. The other group is found along the western Asian coast including Japan, Korea and the Russian Far East.

Giant Panda Ailuropoda melanoleuca The species is now restricted to six isolated mountain ranges in western China: Qinling in Shaanxi Province, Minshan in Gansu and Sichuan Provinces, and Qionglai, Xiangling and Liangshan in Sichuan Province.


3 - How many polar bears are there in the world?

Current estimate is 21.500-25.000. This estimate is arrived at by adding the individual estimates of the sizes of all the populations in the world. However, it is still only an estimate because, while the size of some populations, such as Western Hudson Bay, are quite well known, the size of others in Russia and East Greenland can only be guessed at. This review is done by the members of the Polar Bear Specialist Group for all the world’s ca. 19 populations, and it is done in connection with the regular meetings of the group. The last meeting was in Nuuk, Greenland, in June 2001, and the results from the population review updates are published elsewhere on these webpages.


4 - How far north can we meet polar bears – and how far south?

No reports have put polar bears exactly on the North Pole itself, but ca. 100 miles to the south, at 88°N. Thus, there is no doubt that there are polar bears in the vicinity of the North Pole, though they are probably not abundant because the ocean there is less biologically productive than it is over the continental shelf, at the edges of the polar basin and associated islands. There is little detailed knowledge about polar bear migrations in the Polar Basin, since there has been little research carried on there. The Arctic Ocean basin is among the earth’s most remote areas, and the logistics and cost of such studies are limiting factors. However, there are numerous reports from polar explorers and expeditions that have encountered occasional polar bears in the permanent ice cap around the North Pole.

The furthest south that polar bears live on a year-round basis are in James Bay in Canada, where bears den at about 53°N on Akimiski Island. On a seasonal basis some bears appear regularly as far south as Newfoundland, and they have occasionally been seen in the Gulf of St. Lawrence in years when heavy pack ice have been drifting farther to the south than normal (latitude 50°N).


5 - How large do polar bears get?

Adult males measure 240-260 cm and usually weigh 400-600 kg, although they can weigh up to 800 kg and maybe even more. They do not reach the maximum size until they are 8-14 years old. Adult females are about half the size of males and reach adult size at an age of 5-6 years, when most of them weigh 150-250 kg. Pregnant females can weigh up to 400-500 kg just prior to entering their maternity dens, but almost half of this is fat required to sustain themselves through winter.

Polar bears are the largest living carnivorous quadruped (animal with four legs).


6 - What are the basics of polar bear life history?

Polar bears have a normal life span of about 25 years for males and 30 for females, although a small number of individuals may live longer. In captivity, there have been a number of individuals that have survived for longer than 40 years of age.

The breeding season occurs in spring to early summer (March-June).

The number of cubs per litter is one or two, rarely three. Younger and older females often have only one cub, while 2 or even 3 cubs may be born to females between the ages of about 8 and 20. As for all mammals, the mortality of cubs is quite high, sometimes exceeding 70%. Cubs typically stay with their mother for 2.5 years, but in some areas where the marine ecosystem is less productive they may remain with their mothers for 3.5 and even 4.5 years. In Western Hudson Bay, variable numbers of cubs may be successfully weaned as yearlings. This means that in most parts of their range, females normally mate and gives birth every 3 years.

Both males and females become sexually mature around 4-5 years of age. Females normally give birth at sexual maturity, but it is unlikely that males mate before they are 8-10 years old.


7 - What do polar bears eat?

The main part of the polar bears’ diet is ringed and bearded seals. Ringed seals, often the pups, are caught in the ice, either by smashing through the ice and grabbing newborns in the birth lair, grabbing them after waiting by their breathing hole, or by stalking the seals on the ice. Polar bears also prey on a wide variety of other marine mammals, depending on their availability, including walrus (pups), harp seals, hooded seals, white whales (belugas), narwhal, When on land they have been known to eat Svalbard reindeer, seabirds, geese, and eggs of eider ducks as well as scavenging on the occasional whale carcass. They have also been known to eat berries, grass, and dive for kelp.


8 - Some say that polar bear fur have fiber-optic qualities. Is this true?

No. Polar bear hair does not have fiber-optic properties. It has been postulated that the fur could channel light to the skin, but this was proven to be false (for more information about this issue, you can visit the homepage of Daniel Koon of St. Lawrence University).


9 - What is trichinosis?

Trichinosis is a parasitic disease that you might be infected with if you eat pork or polar bear meat that is not thoroughly cooked. The parasite, Trichinella sp., is a roundworm in the order Nematoda. After the larvae is ingested through infected meat, they are released, reach maturity, and mate in the bear's intestines. The female parasites produce live larvae. The parasites are then carried from the gastrointestinal tract by the bloodstream to various muscles, where they become encysted. It is estimated that 10% to 20% of the adult population of the United States suffers from trichinosis at some time. In many people the disease exhibits no symptoms and is discovered only at autopsy. In others it causes diarrhea and other gastrointestinal symptoms as the worms multiply in the digestive tract. When the larvae circulate through the bloodstream, the patient experiences edema, irregular fever, profuse sweating, muscle soreness and pain, and prostration. There may be involvement of the central nervous system, heart, and lungs; death occurs in about 5% of clinical cases. Once the larvae have imbedded themselves in the muscle tissue, the cysts usually become calcified; however, the infestation usually causes no further symptoms except fatigue and vague muscular pains. There is no specific treatment.



10 - How are they adapted to a cold and wet environment as the Arctic?

Polar bears are marvelously adapted to their arctic surroundings. Their thick winter coats, with glossy guard hairs and dense under-fur, and the thick layer of fat beneath their skin protect them against the cold. The guard hairs also shed water easily, so that after a swim the polar bear can shake itself like a dog to decrease chilling and to dry itself fairly quickly. Being large also helps keep warm.

The white color of the polar bear also serves as camouflage. Polar bears are clever in their use of cover, be it land, water, or ice. This aids both their hunting of seals and their own escape from human hunters. The soles of the bears’ feet have small bumps and cavities that act like suction cups which help to keep them from slipping on the ice.

Probably the most significant adaptation of polar bears to the uncertainties of food availability in the Arctic is their ability to slow down their metabolism (in order to conserve energy) after 7-10 days of not being able to feed, for whatever reason and at any time of year, until food becomes available again. In comparison, black or brown bears can slow down their metabolism only in response to not feeding in the late fall, just before they enter their dens for the winter. If food is removed from black or brown bears in spring or summer when they are not in their winter dens, they will simply starve to death.


11 - Why are there no polar bears in Antarctica?

The distribution of all animals is a function of luck and history. Having everything you need is no guarantee of being able to reach any point on the globe once you are there because it may not be possible to get there in the first place.

Polar bears likely evolved very recently (about 200,000 years to possibly as long as 500,000 years ago) from grizzly bears somewhere off eastern Russia or the Alaskan Panhandle. They are totally dependent upon sea ice for their primary habitat for getting their food (mainly ringed seals and bearded seals). As the world's oceans never have been frozen from the north to the south, polar bears never have had the possibility to reach the Antarctic. Polar bears are strong swimmers but not strong enough to swim to the Antarctic.

Some species have wider distributions because their habitats were connected at some time in the distant past. For example, grizzly bears (also called brown bears) live in the USA, Canada, Russia, Spain, Italy and even Norway! They crossed over a land bridge between Russian and Alaska. The same is true for wolves, wolverines, lynx and many other species.

However, polar bears would really like the Antarctic. In the absence of polar bears, seals and penguins in the Antarctic are not afraid of predators (except leopard seals and killer whales). A polar bear would have a lot of fun and probably get very very fat! On the negative side, the seals and penguins would be devastated. Polar bears are really better off in the Arctic.


12 - How far can they swim and for how long can they hold their breath?

Polar bears can swim steadily for many hours in order to get from one piece of ice to another. They have water-repellent coat and partially webbed feet, which both are adaptations to swimming. Although known individual bears have only been recorded swimming about 100 km or so, they are likely capable of swimming much further if necessary. However, this kind of effort is very expensive in terms of energy, so swimming such long distances is likely not done frequently. The longest a polar bear in the wild has been timed holding its breath while diving is 72 seconds.


13 - How fast can they run?

Polar bears don't normally like to run for long periods, but on a good surface a polar bear can reach speeds of 30 km/h (or 20 mph).


14 - How many polar bears are hunted, and where?

The populations that are hunted are those in North America, Eastern Russia (Chukchi area) and Greenland. The populations in the Barents Sea and western and central Russian Arctic are not hunted.

Although quotas vary, and are set annually based on previous catch history and population assessments, the annual total world catch is about/less than 1000 bears. Most of these are taken by Inuit people in Canadian and US territories.

As a part of focus on sound management of all populations, a lot of attention has been given to try to get solid and representative statistics from the catch in each area. This has been problematic in a few of the populations (see: resolutions from the 2001 meeting of the PBSG in Nuuk, Greenland). Thus, there is some concern about the unknown size of the harvest in some areas, especially in Northeast Greenland, due to a suspected multiyear overharvest.


Author: IUCN/PBSG.
Copyright © 2001 IUCN/PBSG. All rights reserved.
Revised: juni 10, 2002 .