WHAT IS THE LENGTH OF A SNAKE?

Abstract

The way that herpetologists have traditionally measured
live snakes is by stretching them on a ruler and
recording the total length (TL). However, due to the thin
constitution of the snake, the large number of intervertebral
joints, and slim muscular mass of most snakes,
it is easier to stretch a snake than it is to stretch any
other vertebrate. The result of this is that the length of
a snake recorded is infl uenced by how much the animal
is stretched. Stretching it as much as possible is perhaps
a precise way to measure the length of the specimen
but it might not correspond to the actual length of
a live animal. Furthermore, it may seriously injure a live
snake. Another method involves placing the snake in a
clear plexiglass box and pressing it with a soft material
such as rubber foam against a clear surface. Measuring
the length of the snake may be done by outlining its
body with a string (Fitch 1987; Frye 1991). However, this
method is restricted to small animals that can be placed
in a box, and in addition, no indications of accuracy of the
technique are given. Measuring the snakes with a fl exible
tape has also been reported (Blouin-Demers 2003)
but when dealing with a large animals the way the tape
is positioned can produce great variance on the fi nal outcome.
In this contribution we revise alternative ways to
measuring a snake and propose a method that offers repeatable
results. We further analyze the precision of this
method by using a sample of measurements taken from
wild populations of green anacondas (Eunectes murinus)
with a large range of sizes.