The Rattle
The rattle is what defines a
rattlesnake. The structure of the rattle is similar in all species but the shape and size are quite
different and vary considerably. Several island species of rattlesnakes such as the Santa Catalina
rattlesnake (Crotalus catalinensis) and now many of the San Esteban blacktail
rattlesnake (Crotalus m. estebanensis) are losing their rattles.
The first rattle segment emerges after the first shed of a neonate. This first rattle is known as a
button. As the neonate grows, a rattle segment is added with each shed event. These rattle segments are
loosely attached to the next rattle segment. The rattle sound is caused by these segments hitting each other
as the snake quickly vibrates its tail. The tail muscles on a rattlesnake are capable of contracting at an
enormously high rate.
Contrary to popular belief, you cannot tell the age of a rattlesnake by its segments. All segments are
indicative of are the number of sheds the animal has undergone. Even this is not a very good assessment as
rattle segments break off easily and few wild adult rattlesnakes (even captive ones) have all their rattles
since birth. Rattles in younger rattlesnakes will have a more pointed and triangular shape compared to that
of an adult.
All of the Sistrurus have smaller rattles with the pigmy rattlesnake (Sistrurus
miliarius) having very small rattles. On the other side, the tiger rattlesnake (Crotalus tigris) has proportionally larger rattles than any other rattlesnake.
