Biodiversity

Monday, May 15, 2006

THE DIFFERENT METHODS OF REPRODUCTION BETWEEN PLACENTAL AND MARSUPIAL.

The marsupial animals belong to the marsupial order (3). These animals are sharing the class metatheria with the “kangaroo, koala, Tasmanian devil and the Virginia opossum” (3). The female marsupials were found to have being carrying their young ones in a pouch (3). It seems as a pouch is a pocket used by the marsupial to carry their young ones.

The placental are thought to be the one of the group of mammals belonging to “the third subclass of the mammals” (4). They are named placental as the results of their functions, they “connects the growing embryo within the uterus to the circulatory system of their mother” (2). The placenta is the way used for the fetus to get food (3). Before the placental mammals give birth, they take a long process in the growing stage. (3).


It seems as the main different between the marsupial and placental mammals are the rate of gestation. Gestation is the “period that the female keep their offspring in the womb from when they have conceived and when they give birth” (1). It seems as if the process of mating continues in marsupials mammals while in placental mammals stop when they are pregnant and continues after they gave birth (4).

The body of the marsupial mammals are not connected to the embryo (4). It is separated by the embryo protector, amniotic membranes (4). This membrane is known to protect the embryo by separating it from the biological connections with the parent (4). These membrane play an important role, because when “fertilization take place the embryo becomes a new organisms and the immune systems attack it, but because of the protection the attacker becomes unsuccessful” (4).


The more there are few nutrients in the egg there will be few nutrients of marsupial embryo, because “they depends on the egg yolk for their nutrients” (3). The type of “egg yolk reproduced determines the period of gestation of marsupials” (3). It seems as if the marsupial mammals spent short time in reproduction, they can not spend “more than twelve days in reproduction” (3). In the other side the placental mammals takes “weeks and month in reproduction” (3) which is much longer compared to the marsupials mammals (3).


The long period of gestation that occurs within the placental mammals, helps their offspring to be well develop (3). The placenta allows the “nutrients to travel from the mother systems to the embryo and waste are carried out, and this allows the extension of placental maturation (3). The placenta is composed of numerous layers of blood supply; the mother and embryo have their own blood supply” (3).


In conclusion, indeed there are difference mode of reproduction between the placental and the marsupial. During pregnancy of the marsupials the oestrus cycle occurs, while in the placental does not until the whole period of pregnancy is over. The embryo of the marsupial is not connected to the mother while of the placental is connected. The marsupial gives birth very fast as compared to the placental. The main difference between the marsupial and placental mammals is their rate of gestation.

References:


[1]. A Creation Theory into the Origin of Marsupials. [http://nwcreation.net/marsupials.html, accessed on 12/05/2006, 08:00].


[2].The wikipedia contributors, Coordinated Universal Time [Internet], Wikipedia, The Free Encyclopedia; 2006 May 12, 09; 00 UTC [cited May 2006]. Available from: http://en.wikipedia.org/wiki/placenta.


[3].The wikipedia contributors, Coordinated Universal Time [Internet], Wikipedia, The Free Encyclopedia; 2006 May 12, 09; 30 UTC [cited May 2006]. Available from: http://en.wikipedia.org/wiki/Marsupials.


[4]. "Mammal," Microsoft® Encarta® Online Encyclopedia 2006
http://encarta.msn.com © 1997-2006 Microsoft Corporation. Available from: http://encarta.msn.com/text_761561349__1/Mammal.html


Ms Evelyn Maleka
CILLA CSIR
P.O. Box 395
Pretoria,
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Tel: (012) 841 2133
Fax: 012 842 7024.
Email: emaleka@csir.co.za
http://malekaevelyn.blogspot.com/

5 Comments:

  • This comment has been removed by a blog administrator.

    By Blogger Maleka Evelyn, at May 18, 2006 12:53 PM  

  • Be careful, you came very close to plagiarism in this essay.

    Please put all your references in the text and in your reference list. You used information from the Opossum Society of the United States' website
    http://www.opossumsocietyus.org/opossum_reproduction_and_life_cycle.htm
    without putting it in your reference list.

    By Blogger Gwen, at May 26, 2006 2:50 PM  

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