Species profile: Polar bear

Hello again, welcome back to animals under threat. Today, we will be covering the largest carnivore in the arctic circle and is considered to be the largest bear species to be alive currently. This species of bear is under threat from loss of sea ice due to global warming, pollution, and human interaction. Give a warm welcome to the Polar bear (Ursus maritimus).

Polar bears are characterized by their white fur, long neck, small head, rounded ears and short tail. Male polar bears are larger than the females as they can weigh up to 410-720 kg or 900-1,600 pounds. Sometimes nicknamed the sea/ice bear, polar bears live throughout the arctic region and travel across ice floes to search for seals. It has not natural predators or rival species and has no fear of humans (Britannica.com, 2019).

diagram by https://www.britannica.com/animal/polar-bear 

Polar bears have adapted to their arctic home with unique adaptions. They have a thick coat of fur which covers a layer of fat that keeps the bear warm. The bear’s fur also grows over their paws which helps protect them against cold surfaces and help the bear’s grip on the ice. Polar bears have black skin under their white fur which absorb the sun’s rays to help keep the bear warm (Nationalgeographic.com, 2019). Polar bears can swim up to a pace of six miles per hour by paddling their front legs and using their back legs as a rudder (Worldwildlife.org, 2019).

polar bear's fur and skin by Jon Aars / Norwegian Polar Institute / WWF-Canon

Female polar bear reaches mature age between 4-5 years old and can start breeding. Pregnant polar bears enter a den that is usually located in a snow drift or slopes in order to give birth. Usually twin cubs are born although there have been cases where only one cub is born or triplets. The cubs feed on their mother milk while the mother fast until she is ready to open the den. They stay near the den as the cubs learn to walk and play while the mother feeds on the vegetation that is around the den. The mother will then lead her cubs out to the sea ice to hunt seals as the cubs observe their mother’s hunting. There has been rare case of cubs that have been adopted by other female polar bears after they have been abandoned. The mother will look after her cubs for 2 and half years leaving them to survive on their own (Wiig et al, 2015).

                                                                         polar and cub by AWeith

As polar bear has no fear of humans, they enter human settlements to find food and exploring the area. This has led to conflict between humans and polar bears as polar bears are shot and killed by humans defending their homes and food (Wilder et al, 2017). Due to the increase in global warming, the sea ice that the bears depend is decreasing which makes it harder from the bears to hunt and have to swim longer leading to drowning. With pollution from human settlement such as plastic bags been found in polar bear stomach leading to death of the animal due to eating the plastic (Regehr et al, 2016).


Next time, we will be covering a species of sea snake that has an unusual name.


References

https://www.britannica.com/animal/polar-bear retrieved 21/12/19

https://www.nationalgeographic.com/animals/mammals/p/polar-bear/ retrieved 21/12/19



Regehr, E.V., Laidre, K.L., Akçakaya, H.R., Amstrup, S.C., Atwood, T.C., Lunn, N.J., Obbard, M., Stern, H., Thiemann, G.W. & Wiig, Ø. 2016, "Conservation status of polar bears (Ursus maritimus) in relation to projected sea-ice declines", Biology letters, vol. 12, no. 12, pp. 20160556.



https://www.worldwildlife.org/species/polar-bear retrieved 21/12/19



Wiig, Ø., Amstrup, S., Atwood, T., Laidre, K., Lunn, N., Obbard, M., Regehr, E. & Thiemann, G. 2015. Ursus maritimus . The IUCN Red List of Threatened Species 2015



Wilder, J.M., Vongraven, D., Atwood, T., Hansen, B., Jessen, A., Kochnev, A., York, G., Vallender, R., Hedman, D. & Gibbons, M. 2017, "Polar bear attacks on humans: Implications of a changing climate", Wildlife Society Bulletin, vol. 41, no. 3, pp. 537-547.



picture references

polar bear skin by Jon Aars / Norwegian Polar Institute / WWF-Canon

polar and cub by By AWeith

Species profile: Blue whale

Hello again, welcome back to animals under threat. Today, we will be covering the largest marine mammal currently alive today. Its current geographical range covers all the oceans in the world and is under threat from whaling. Please welcome the Blue Whale (Balaenoptera musculus).


Growing over 30 meters in length, the blue whale is currently the largest marine mammal alive today. Feeding on its favourite food, which is krill, the blue whale can weigh up to 200 tonnes (Britannica.com, 2019). Blue whales belong to the baleen whale family which means they have fringed plates that contains finger-like material called baleen. The whale swallows a mouthful of water and its tongue pushes the water through the plates leaving the krill behind (nationalgeographic, 2019).

Diagram by https://www.britannica.com/animal/blue-whale

Unlike other whale species that live in pods, blue whale prefers to live alone or in pairs. A blue whales call is a low frequency whistle that reaches 188 decibels which is louder than a jet engine. This call is useful for finding a mate in the ocean (wwf.org.au, 2019). Female blue whales carry a calf for a year before it is born. The calf can weigh up to 3 tonnes and 25 feet long when born and feeds on its mother’s milk, gaining 200 pounds every day for its first year (Worldwildlife.org, 2019).

mother and calf by https://au.whales.org/whales-dolphins/species-guide/blue-whale/

picture by https://en.wikipedia.org/wiki/Blue_whale

Blue whales are under threat from whaling, entanglement of nets, pollution and global warming. Baby and juvenile whales are at risk of drowning due to been caught in nets as they are unable to free themselves. Adult whales are at risk from whaling as they are hunted for their meat due to their size. Pollution from plastics has led to the whales dying due to the plastics they ingested cannot be removed. Global warming has increased the temperatures in the water which affects the whale’s food supply as the krill are dying due to the temperature (Clapham et al, 1999).

Next time, we will be covering the largest carnivore in the arctic circle and is considered to be the largest bear species to be alive currently.  

References

Clapham, P.J., Young, S.B. & Brownell, R.L. 1999, "Baleen whales: conservation issues and the status of the most endangered populations", Mammal Review, vol. 29, no. 1, pp. 37-62.

Cooke, J.G. 2018. Balaenoptera musculus . The IUCN Red List of Threatened Species 2018: e.T2477A50226195. http://dx.doi.org/10.2305/IUCN.UK.2018-2.RLTS.T2477A50226195.en.

https://www.nationalgeographic.com/animals/mammals/b/blue-whale/ retrieved 11/12/19

https://www.britannica.com/animal/blue-whale retrieved 16/12/19

https://www.worldwildlife.org/species/blue-whale retrieved 16/12/19

https://www.wwf.org.au/what-we-do/species/blue-whale#gs.mmndbc retrieved by 16/12/19

Picture references

https://en.wikipedia.org/wiki/Blue_whale

https://www.britannica.com/animal/blue-whale

https://au.whales.org/whales-dolphins/species-guide/blue-whale/