Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Earth worms

  1. Aug 14, 2004 #1


    User Avatar
    Gold Member

    When cut in half they can regrow the severed part, but how?
    is the information that enables this re growth encoded in the
    DNA, what mechanism initiates this re growth.
  2. jcsd
  3. Aug 18, 2004 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    I'm no biologist, and all of this is from memory, so it's probably mostly wrong.

    AFAIK, body part regeneration is controlled by the Hox genes, which essentially specify where all the body parts should be in an organism. If you take fruit flies and modify their Hox genes, they'll grow legs where their antennae should be, that sort of thing.

    The Hox genes are responsible for expressing proteins or hormones that then instruct dividing stem cells in the body to differentiate into a specific kind of tissue. Differentiating cells figure out where they are in the body by essentially sniffing around for these chemical signals to see what's near them.

    I also believe I have read that stem cells can be called into action by chemical signals of injury, and actually move through the body to the site of the injury to participate in the healing.

    So, I believe the body part continues to grow from these stem cells until the proper location for say, skin is reached. Skin grows there, and the growth goes no further.

    - Warren
  4. Aug 18, 2004 #3


    User Avatar
    Science Advisor
    Gold Member
    Dearly Missed

    Warren you are a trove of knowledge and an inspiring example:
    inorganic techies and astronomers should all know about fruit flies and Hox genes as well
    it is fascinating and it would do them good

    I remember another detail.
    Another thing that helps the severed worm is that
    an earthworm (so my 9th grade science teacher told us)
    can have multiple hearts----distributed all along its length

    It might start out with 5 hearts and then it gets severed into
    a piece with 2 and a piece with 3

    so the pieces can keep functioning and can both thrive
    and go around eating dirt as nature intended
    and, in the course of time, grow longer

    the earthworm is somewhat modular in design

    its other organs including even its thinking apparatus
    are distributed along its length, according to my teacher,
    in a similarly modular fashion.
  5. Aug 18, 2004 #4


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member


    http://www.scaquarium.org/curriculum/iexplore/three_five/units/decompositionI/decomp_background.htm [Broken]

    I searching to find info on the molecular biology of segment regenration but results have been limited.
    Last edited by a moderator: May 1, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook