Reproductive System - olivia collings
Scientific name: ursus maritimus meaning, ice bear Diet: Carnivore Class: Mammalia Average life span in wild: 25-30 years old Size: 2-2.6 metres tall Left in the wild: 20,000-25,000
Polar Bears mainly inhabit the enitre ice lands of the Artic. Unlike other bears, Polar Bears can swim, they have even been spotted swimming 160 kilometres away from land! Like any other animal, Polar Bears have to migrate. The Polar Bears that live in Hudson, Canada migrate onto land in the summer when the ice melts, relying on fat reserves to survive until the sea freezes again in the late November or early December. During the winter and spring months they take to the sea to hunt their prey of seals.
Female Polar Bears sexually mature around the ages of 4-5. Male Polar Bears sexually mature around the ages of 5-6 although, most male Polar Bears don't successfully mate until they are around 9 years old.
Breeding mainly takes place during April and May. When a male has successfully fought off the other male competition, the male and female stay together for a week or more as females are induces ovulators. Meaning that the act of mating causes the female to release an egg for fertilisation. Several days of mating interactions may be required to stimulate ovulation and guarantee fertilisation.
Like humans, the sperm enter the female's vagina, through the cervix which is open while the female is ovulating. Into the uterus, some of the sperm go through the left Fallopian Tube and some will go to the right. The sperm will meet the egg that has been released from the ovary. Only one sperm can fertilise the egg, when it has been fertilised it will continue to travel to the uterus and bury itself in the thick lining where it will develop. Therefore, Polar Bears are cross and internal fertilisers.
The advantage of being an internal fertiliser is that there is a much higher chance the egg will be fertilised because there is not a large space that the sperm can go. The disadvantage can be relating to the fact that female Polar Bears are induces ovulators, meaning there needs to be a week between the male and female meeting and them mating. This allows more time for error such as, illness, another male coming in ect. Like humans, only one female gamete (egg) is released and millions and millions of male gametes (sperm) are released.
After the egg is fertilised, it burys into the thick uterus lining to develop from a zygote to embryo to fetus. Therefore, it is internal development.
Polar Bears are viviparous, meaning they give birth to live young that have developed in the mothers body. Polar Bears have a gestation period of 8 months, this is the time between fertilisation and birth.
The advantage of internal development is the offspring are protected from the elements, any predators and any other potential harm. A disadvantage is obviously nutrition, if food is scarce the mother and the baby will both not be able to obtain the nutrition needed for a healthy life/development.
After the cubs are born, they are nurtred until they are about 2 1/2 years old when they go off and start their own life. After the cubs leave the mother will try to mate again.
When the female Polar Bears release and egg, they usually only release 1-2 eggs, as they need lots of nurturing and they are more likely to survive if only a couple of offspring are produced. As a result the mortality rate is very low in Polar Bears.
Polar Bears are K-Selection animals, meaning they give lots of parental care. This is because there are a lot of skills to teach the new cubs; hunting, finding food, swimming, being protected from the elements ect.
The advantage of this is that the cubs will be more prepared for the world when it leaves the mother. The disagvantage being that the mother can only mate again once the cubs has
- A male Polar Bear's neck is wider than their head, therefore they can't wear tracking collars
- A female Polar Bear often weighs between 225 and 270 kilograms
- A baby Polar Bear weighs about 500 grams when they are born
- Baby Polar Bears have learned to stay still when their mother is hunting, if they move they are disciplined by their mother with a whack on the head!
- Humans the the Polar Bears only predators
- Male adults can grow to be more than 10 feet (3.3 metres) tall and over 515 kilograms
- Polar Bears can swim up to 161 kilometres per hour
- Polar Bears' fur isn't actually white. It's transperent (see-through), made up of a thick hollow core. When the light reflects off them, it makes it seem white!
- They are obsessive about keeping clean, grooming for about 30 minutes are eating
- Polar Bears don't hibernate, pregnant females will curl up in their den and become less active, but they will continue hunting and eating. Land Bears' body temperature drops to about 0 degrees celcius while Polar Bears remperature never drops below 30 degress celcius
- Polar Bears have 42 teeth usually about 3-4 centimetres long
- Their skin is actually black
Polar Bears. (2002). Retrieved September 11, 2013, from Seaworld: http://www.seaworld.org/infobooks/polarbears/pbbirth.html
Polar Bear Habitat. (2013, April). Retrieved September 10, 2013, from Endangered Polar Bear: http://www.endangeredpolarbear.com/habitat.html
Polar Bear Reproduction. (2013, September). Retrieved September 10, 2013, from SeaWorld: http://www.seaworld.org/animal-info/info-books/polar-bear/reproduction.htm
Polar Bears. (2013). Retrieved September 11, 2013, from National Geographic: https://animals.nationalgeographic.com.au/animals/mammals/polar-bear/
Polar Bears Migratory Patterns. (2013). Retrieved September 10, 2013, from The Guardian: http://www.theguardian.com/environment/2013/mar/20/polar-bear-hunting-migration-warming-climate
The Polar Bear. (2013, April 20). Retrieved September 10, 2013, from Sammy See: http://sammysee.weebly.com/reproductive-system.html
FAQ's. (n.d.). Retrieved September 11, 2013, from Polar Bears International: http://www.polarbearsinternational.org/about-polar-bears/faqs
Photos from/by David Merefield (Olivia's uncle), in the Artic.