Mexican Pigmy Rattlesnake (Sistrurus ravus)

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The Mexican Pigmy Rattlesnake

The Mexican Pigmy Rattlesnake (Sistrurus ravus) is a smaller, more compact version of the typical desert rattlesnake. Rattlesnakes are currently threatened because of clearing of their native habitat and hunting, as their skin is most often used in ‘snakeskin’ accessories, such as boots and handbags. Rattlesnakes all belong in the pit viper family, and all members of this family have heat-sensing pits on the sides of their heads that they use to help locate prey.

Mexican Pigmy Rattlesnakes are native to Mexico and are found in temperate forests. They are most often found in pine and oak forests in bunches of grass or hiding underneath leaves or stones.

Mexican Pigmy Rattlesnakes are relatively small in size for their species, and typically reach a length of about 13 inches (35 cm). Rattlesnakes are typically very thick snakes with rough brown scales, Mexican Pigmy snake scales being greenish-brown to deep brown. Their underbellies are usually much lighter, verging on white, and they have approximately 30 dark gray to black rectangular markings on their backs. They are also able to look bigger and more vicious by inhaling as their right lung extends almost the entire length of the body. The fangs of rattlesnakes are hollow and fold back against the roof of the mouth. When biting, the snake flips the fangs forward in order to inject the venom. These snakes also have specialized scales on their underbellies called scutes, which push along the ground when the snake flexes its muscles. The trademark rattle of the rattlesnake develops over time and is made up of several connected segments. Every time a rattlesnake sheds its skin, or molts, a new segment is revealed.

Interesting Fact: The venom of the rattlesnake is made up of two different types of poison. One type makes the heart and lungs slow down and not function correctly, and the other swiftly breaks down skin tissue. There are, however, only about 12 listed human deaths from rattlesnake bites per year.

Rattlesnakes hunt by hiding and waiting. They will often coil up in a sheltered, hidden location and wait for their unsuspecting prey to wander by. They will often wait by often-used travel paths and are extremely patient animals, sometimes waiting for days for their meal to deliver itself. The snake will then strike, sinking its fangs into the animal, and inject venom. It will then release the animal and let it run away, tracking it until the poison takes effect. Pigmy rattlesnakes usually eat lizards and small rodents.

Little is known about the reproductive habits of the Mexican Pigmy Rattlesnake specifically, but other pigmy rattlesnakes have been studied extensively. These snakes have extended mating rituals where the male will stay close to the female for many days, and they have been found basking in the sun, curled around one another. They stay close for several days and then move apart, and the female will go off by herself. Mating usually happens between October and December, but the reproductive system goes dormant during the coldest winter months, so the female will store the sperm until around April when fertilization actually finally occurs. Baby snakes are born with a stub of rattle, called a prebutton, which usually falls off a few days after birth. This is replaced with the first segment of the rattle, called a button. The mother snake will say with the babies only for a few days and then leaves them on their own. Snakes are able to hunt for their own food just minutes after they are born.

Further Information on the Mexican Pigmy Rattlesnake:

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Bibliography:
Rattlesnake. Encarta Encyclopedia, © 2000.
Rattlesnake. Accessed 08/21/04 at http://www.therfcc.org/rattlesnake-7532.html.
Biology Department: Pigmy Rattlesnakes, Pig info. Accessed 08/21/04 at http://www.stetson.edu/departments/biology/piginfo.shtml.
Sistrurus ravus. Accessed 08/21/04 at http://www.vivanatura.org/Sistrurus%20ravus.html.