Nature Bulletin No. 90 November 2, 1946
Forest Preserve District of Cook County
Clayton F. Smith, President
Roberts Mann, Supt. of Conservation
Curled up on a fallen leaf, we found a tiny snake basking in the autumn
sunshine. His back was dull brownish-gray but his belly was bright red,
and he was only 10 inches long. It was the Red-bellied Snake, the
smallest species that inhabits the Chicago region, so little and so
secretive it is rarely seen. Only the Worm Snakes found in central and
southern Illinois are smaller. The red-bellied snake is usually less than
12 inches in length, living on earthworms, slugs and possibly insects.
When born they measure less than 3 inches and can coil up on a dime
with room to spare.
We finally succeeded in putting this one into a small match box but it
was a job. His hard smooth scales made him slippery as an eel. We took
him to Trailside Museum and dumped him out on the glass top of a
showcase where he wriggled and skidded in vain attempts to escape.
Snakes require a surface with obstructions and some roughness in order
to travel. Try putting a snake on loose sand and watch it crawl. Every
part of its belly touches the ground and it flows along in a series of S-
curves. On the back of each curve you will notice the sand has been
pushed up. The body pivots and pushes sidewise against these piles and
is propelled forward. They swim in water with the same motion.
Snakes have a backbone with a great many vertebrae, some having
about 300 whereas a man has only 33 or 34. To each vertebra is
attached a pair of ribs. On the belly, from neck to tail, are as many
broad overlapping plates as there are vertebrae, each attached to the
ends of a pair of ribs and controlled by a system of muscles. Some
thick-bodied snakes, such as rattlesnakes and the cottonmouth
moccasin, can crawl slowly in a straight line along the ground, or even
up a tree, by inching a few belly plates forward, then a few more,
synchronized so that there appears to be wave after wave traveling from
neck to tail. But for speedy travel they use the sinuous movement.
When hunting, they glide with the head and a third of the body erect.
The maximum rate of travel know, by any kind of snake, is 3 miles per
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Update: June 2012