Mammals and Navels Best answer on the web

Author: webmaster     07 30th, 2010 in xn--00t609f.com     edit

  • I assume all mammals are nourished in the womb through a placenta and umbilical cord. If this is the case, what happens to the cord of other animals at birth? Do all primates/mammals, then, have navels?


  • http://www.madsci.org/posts/archives/sep2000/967827843.Zo.r.html would have been good, too.


  • Ingesting the placenta also gives the mother an nutrient-rich protein boost after her labor efforts, as she will have been isolated and her energy spent during the birth. This is not limited to "wild animals," as several human societies still eat the placenta after giving birth. I believe this practice is coming back into style in Europe. There are some recipes out there for freeze-dried or pate-style placenta. Really. http://www.dear-midwife.com/faq.html


  • butterfly said:
    "There are a couple of aplecental mammals, including monotremes
    (platypuses) and marsupials (kangaroos, etc)."

    I think this is perhaps a misleadingly simplistic statement. There are currently considered to be 276 species of mammals that are monotremes or marsupials, as opposed to placentals. However. . .
    Monotremes (platypuses and echidnas) lay eggs and nutrients are provided to the embryo from the yolk sac (the direct evolutionary basis of the placenta).
    Most marsupials (with the exception of bandicoots) have very simple placentas (choriovitelline placentas) that are more or less yolk sacs without eggs.
    Bandicoots, (true) placental mammals, and some snakes have more complex placentas (chorioallantoic placentas).
    Yes, some snakes give live birth, in fact "viper" comes from "viviparous", "bearing live young". Some people have estimated that live birth has evolved 75 different times among reptiles.
    I really couldn't say how all this fits in with navels, though. I've never heard of a snake with a belly button.
    My personal favorite site for zoology information is the Animal Diversity Web: http://animaldiversity.ummz.umich.edu/index.html

    Its sections on mammals and crocodiles are particularily informative.


  • my understanding is that when the babies are born, the mother typically licks the baby clean, and bites the umbilicus.
    I wonder at the reference of "placental mammals"... does this indicate that there are non-placental mammals that use a different system of nutrient transport?


  • What an unusual and interesting question. A question alot of us probably never thought about.
    The belly button, or umbilicus, represents the site where the umbilical cord attaches to the fetus during development. The umbilical cord transports blood between the fetus and the placenta. All placental mammals have a placenta, and an umbilical cord. In the placenta the fetal circulation releases wastes in exchange for oxygen and nutrients from the mother. In the case of animals which carry more than one fetus at a time, each fetus must have an umbilical cord in order to survive. However, these multiple umbilical cords do not usually get tangled. The main reason is that each embryo is contained in the mother’s uterus as a single unit. There are a series of membranes that surround the developing embryo and the umbilical cord, thus isolating them from neighboring structures. After the baby is born, the umbilical cord is usually broken or tied off and cut. The stump attached to the baby falls off within a few days, leaving the belly button behind as the only reminder of life 'in utero'.
    Virtually all mammals have umbilical cords and hence navels, which are simply scars left at the site where the umbilical cord was attached to the body. The difference between human navels and animalnavels is the appearance. Cats navels are basically an elongated scar located just astern of the rib cage. It's quite understandable that they are often overlooked since it is hidden by hair. In dogs they appear as small scars along the stomach, rather than indented belly buttons. These scars usually fade away after a few years, but you can still see them in puppies
    Information was found on the following sites:

    "BBCi - Science Shack"
    http://www.bbc.co.uk/science/scienceshack/articles/questions/q_ou74.shtml
    "The Life Museum"
    http://www.fiocruz.br/emvida/porque_resp5_jogos_e.html

    "The Straight Dope"
    http://www.straightdope.com/classics/a1_001a.html

    "MadSci Network"
    http://www.madsci.org/posts/archives/aug98/902945879.Zo.r.html

    "Reeko's Mad Scientist lab"
    http://www.spartechsoftware.com/reeko/qanda.htm

    Keywords used:
    mammals "umbilical cords" navels
    ://www.google.com/search?sourceid=navclient&q=mammals+%22umbilical+cords%22+navels
    Best of luck,
    rainbow-ga


  • This is a great start. But, I'm still not understanding how animals can "tie off" and "cut" the cord from the placenta. Do they use scissors, teeth....?


  • Hi Etterman,

    Many domestic mammals will be in the care of humans while giving birth. This is the time the umbilical cord is cut and then tied. But amongst wild animals, "the first thing that the mother will do is to clean the babies by licking them dry. She will also cut the umbilical cord by biting through it near the baby's body. No blood will be lost because the umbilical cord does not function any more. Finally, the mothers of many species of wild mammals often clear away the amnion, placenta and umbilical cord by eating them. This is important because the blood in the placenta could attract predators to the helpless, new-born offspring"
    "The Open Door Website"
    http://www.saburchill.com/chapters/chap0038.html

    Regards,
    rainbow-ga


  • There are a couple of aplacental mammals, including monotremes (platypuses) and marsupials (kangaroos, etc).
    See: http://www.ucmp.berkeley.edu/mammal/monotreme.html for more info.
    ((you have to love ap biology))









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