MadSci Network: General Biology

Re: Do earthworms regrow after being sliced into two or more pieces?

Date: Thu Dec 3 20:05:59 1998
Posted By: Tye Morancy, MadSci Admin
Area of science: General Biology
ID: 910831463.Gb

   Hello Lisa,

     I apologize for the delay, but it seems as though the question bounced off 
a few people before me.  Well, the questions were very good, I'm glad to hear 
of your students being so inquisitive about science and nature.  So lets get to 
the answers...

     The first question asked was whether or not an earthworm could regrow 
segments of its body if it got cut into 2 or more pieces.  I would have to say 
no, because a worm has internal organs, a neural cord, and a simplified 
circulatory system, which means that if we slice them up, important systems to 
the worm's life functions are stopped and the worm would not survive.  An 
earthworm's organs include a simple heart, a digestive system, and a very 
simple brain.   

     Next was a question about whether or not they have noses.  Earthworms 
don't actually have noses since they only have one sensory organ, which is the 
sense of touch.  

     They also wanted to know what earthworms do in the winter.  Earthworms 
need to live in moist soil containing organic matter to provide them with 
food.  They burrow and "eat" large amounts of soil as they go.  Once they've 
eaten the soil, their digestive system takes out things like vegetable remains 
and nutrients.  Earthworms normally live in the upper layers of the soil, but 
when the winter comes they burrow much deeper to escape the frost.  Similiarly, 
earthworms will burrow deeply into the soil when the weather gets hot so they 
can avoid drying up (dehydration) and stay cool.  Earthworms also like to avoid 
sunlight and so they sometimes come out at night to feed and shed their skin.  
They will also surface and come out under unusual conditions like when there 
are heavy rains since their burrows get flooded.  They can also burrow quite 
fast because of a set of little bristles on the sides of their bodies which 
enable them to move around.  
     Earthworms actually have one brain as we know it.  The question as to 
whether they have nine of them or not is understandable, because a worm's 
nervous system consists of a simple brain, a neural cord, and a bunch of 
segments of nerves all along their body called ganglia, which are classified as 
somewhat similiar to the brain material.
     Some cool facts for them:
        ---There are over 1000 different kinds of earthworms.
        ---Earthworms are generally uniform in color, pale red, but can also 
           vary from dull pink to dark brown.
        ---Many types of earthworms grow to only a few centimeters long, but 
           some tropical types can grow to as long as 11 feet!  
        ---Some types can live for ten years or longer.

     I hope this helped you out Lisa.  If your students would like to send us 
questions directly, they should definitely be encouraged.  We have alot of good 
people who can answer their questions in a way that they can understand.  

Tye Morancy

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