Re: how fast is an earthworm?

Hi Diana:
I had a look around, and I didn't find any measurements of the speed of
an earthworm.  However, I was able to find a study on size and speed in
one species of earthworm (Lumbricus, which is the most common
genus of earthworms), by Dr. Kim J. Quillin of the Department of
Integrative Biology at the University of California Berkeley, entitled Kinematic scaling
of locomotion by hydrostatic animals: ontogeny of peristaltic crawling by
the earthworm Lumbricus errestris.

From the equation she gives in her abstract, I was able to construct
the following graph:



On the graph, the speed of the earthworm (in centimetres per second) is 
on the left, and the size of the earthworm (in grams) is on the bottom.
So, as an earthworm gets bigger, its able to crawl more quickly, as you
might expect.

To break this down for you, I picked 3 sizes to figure out speeds
(they're marked by dots on the above graph):

The very tiniest earthworm (about 0.012 grams) is able to crawl at
about 0.2 centimetres per second, which works out to about 27 feet per
hour (not bad!)
A medium-sized earthworm (about 4 grams) is able to crawl at about one
and a half centimetres per second, which is about 185 feet per hour.
The biggest earthworm (about 8 and half grams) is able to crawl at
about 2 centimetres per second, which is about 240 feet per hour

Hope that helps!

Rob Campbell, MAD Scientist