MadSci Network: General Biology
Query:

Re: How can you tell if a earthworm is alive??

Date: Tue Feb 20 21:40:36 2001
Posted By: Allison J. Gong, Graduate student
Area of science: General Biology
ID: 982539124.Gb
Message:

Hello Jenny,

Your question is a very interesting one.  You are correct in saying that you 
can't tell if an earthworm is alive by feeling its pulse.  However, if you 
can observe your earthworm under a dissecting microscope, you might be able 
to see blood moving anteriorly (tail --> head) through its dorsal blood 
vessel.  

Then again, it will be difficult to see any blood flow at all when the 
worm's metabolic processes slow down due to the cold - a cold, barely-alive 
earthworm will look an awful lot like a cold, dead earthworm.  And an 
earthworm's blood flow isn't the most dynamic thing even under the best of 
circumstances, so maybe we should find another measure of the worm's 
"liveliness."

You could try measuring some more visible response to the cold, such as 
lethargy or decreased burrowing activity.  Earthworms will burrow into soil 
if you shine light on them, so you could put the worms in the freezer for 
various amounts of time, then remove them and shine a light on them, and 
time how long it takes them to start burrowing.  Alternately, you could 
measure how reactive the worms are to poking after their stays in the 
freezer.  Of course, by shining a light on the worm you'll also be heating 
it up, which would be a confounding factor for your study.  If you could 
devise a way of giving them light without heat, that would be ideal.

One thing you should know about earthworms before you get started, however.  
Earthworms are extremely sensitive to desiccation, and the inside of a 
refrigerator or freezer is a very dryinc place.  Your worms will dry up 
after only a few minutes if you don't give them any protection.  If you're 
going to do this experiment, put the worms in small cups, covered, and 
buried in damp soil.  This will protect them from desiccation, and they'll 
still be subject to your cold treatments.  

And one last thing.  Please be kind to the worms.  They may be only worms, 
but no living creature should suffer any more than is absolutely necessary.

Thank you!

Allison J. Gong
Mad Scientist  




Current Queue | Current Queue for General Biology | General Biology archives

Try the links in the MadSci Library for more information on General Biology.



MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci


MadSci Network, webadmin@www.madsci.org
© 1995-2001. All rights reserved.