Friend or Foe, The Lizards of the Mohave Desert.
Ronald R. Espenschied
COM/156
November 3, 2013
Bobbie Sepulveda

Friend or Foe, The Lizards of the Mohave Desert. If you ever find yourself in Southern Arizona or Southern California it would be well worth your time to take a hike through the beautiful Mojave Desert. For what some consider to be a harsh dry climate the abundance of different types of animal life is truly amazing. Of the different types of animal life the lizard population is one the most diverse with over fifty different lizards from eight different species (Brennan, 2008). Unlike other inhabitants of this area, most of the different lizards that you could come across are completely harmless even though they may look like they are not. However, there is danger so when in the Mojave Desert it is important to know which variety of lizard is venomous, how to tell the difference, and what you should do if you encounter one. The Mojave Desert is home to a diverse population of lizards with 56 different lizards from eight different species (Brennan, 2008). Each different lizard varies in both its appearance and its size; this is an important thing to know when trying to identify them. While most are tan or gray to blend into their environment there are some that display vibrant blue, green, yellow, and red colors and are quite beautiful. Although a person might think that these colors would suggest that they are venomous they are not harmful. The lizards that display these bright colors use them mainly for their defense from predators. With all of the subtle differences a person would think that determining which species a lizard belongs to would be a daunting task, but with just a little knowledge it is much easier than they may think. There are three things to look for when trying to decide which species a particular lizard belongs (Brennan, 2008). The first thing to look at is the length and shape of the tail. While most lizards have tails equal to the length of their main body there are some varieties where the tail is only half the length. The next thing to look at when looking at the tail is weather it is slender or fat. Those with slender tails have the ability to “throw” their tails as part of a defensive mechanism and thus fall under one of two species. The first one of the species is the most common known as the Iguanidaet (Brennan, 2008). The second is the Teiidae or whiptail lizards (Brennan, 2008). The easiest way to tell the difference between these two species is to look at their stripes. The stripes on the Iguanidaet species are made up by spots that go around the lizards body. The stripes on the Teiidae species run from the back of the head to the end of their tails. The second thing to consider is the time of day that they are active, are they nocturnal, meaning that they are active at night, or diurnal, meaning that they are active during the day. The nocturnal lizards fall into a species known as Xantusiidae and contain three different subspecies (Brennan, 2008). The final thing to look at is the shape of the head, is it round, oval, or arrow shaped. The head shape of the lizard is directly related to where they make their home and what they eat. The shape of the head of a lizard is unlike other animals where the shape of their head helps to determine if they are of a venomous species. The lizards with a rounded head make their home above ground in and around foliage and are normally herbivores meaning that they do not eat other animals or insects. If a lizard has an oval head shape they also live in and around foliage but live mainly underground and will eat the foliage or small insects. Finally those with arrow or diamond shaped heads can be found anywhere and live underground only coming out to hunt and eat. These lizards are strictly carnivorous meaning that they eat other animals or insects. Living in what is considered such a harsh environment a person would think that a large percentage of the lizards would be venomous, but the truth is there are only two venomous lizards in the world (Beck, 2004). Of those two species there is only one, the Gila Monster, which calls the United States, and more specifically the Mojave Desert its home. “This lizard is a member of Helodermatidae, the only family of venomous lizard in the world” (Brennan, 2008, p1). Unlike the other lizards that you may run across, it is easily distinguishable mainly because of its size. The Gila Monster is the largest lizard to inhabit the Mojave Desert reaching up to eighteen inches in length with a short fat tail, which is where they store fat (Beck, 2004). They are the slowest moving of any of lizard, they are non-aggressive, and mainly live underground spending only three to four weeks a year above ground to do their hunting (Brennan, 2008). Another visual key letting you know that it is venomous is the three to four black rings on the tail like those found on the numerous venomous snakes in the region. Unlike venomous snakes, the Gila Monster delivers its venom from glands in their lower jaw, not on the top, and through grooves in the teeth of the lower jaw (Brennan, 2008). The Gila Monster is non-aggressive and its venom is only used for two different reasons. The first is to subdue its prey by “paralyzing the cardiac and respiratory system” (Freedman, 2008, p1) of small animals such as other lizards and rodents. The second use for the Gila Monsters venom is for defense from predators and is only used when the animal is cornered, feels threatened, or when touched or picked up. The first thing to remember if you come into contact with one of these animals is to keep a safe distance and do not try to touch or pick up the animal. While they are slow moving and non-aggressive, they are venomous and will use that venom to protect themselves. The venom is rarely fatal to humans who get appropriate medical care, but according to Brennan the bite from a Gila Monster is known to be very painful. The reason for this is not only from the venom, but also because the animal bites with a grinding, chewing motion which often times causes the teeth to break off and become imbedded in the wound (Beck, 2004). According to the Poison Control Center the first thing that a person should do if they do get bitten by a Gila Monster is to thoroughly rinse the bite area immediately to reduce the risk of infection. The next thing that they need to do is to seek medical attention as soon as possible. A person that has been bitten can expect to become thirsty, disoriented, and weak shortly after the initial bite (Campbell, 2007). Additional symptoms of a bite could include dizziness, nausea, and tremors in the extremities that will continue to get worse without medical treatment (Campbell, 2007). The treatment for all of these symptoms is fairly general and can include antibiotics to stop the spread of any infection and anti-nausea medication. There is no anti-venom for Gila Monster venom because the venom is not considered fatal to humans. The human body is able to endure and process the venom out of the blood stream with just the aid of antibiotics and drinking plenty of water. While the bite from a Gila Monster is not fatal to humans, remember that their bites are extremely painful both during and after the bite occurs so be cautious and keep yourself safe by keeping a safe distance. Exploring the beauty of the Mojave Desert and observing the wide variety of animal life that it contains can be a memorable experience for even the novice outdoorsman. For the lizard lover there is no better place in the United States to see such a wide variety inhabiting one place. When you go remember that it does contain risk and one of the only two venomous lizards in the world (Beck, 2004). Knowing how to distinguish between the different species of lizards will help to keep you safe, knowing what to do when you encounter these animals will keep you safer. Although the chances are low, it is also important that you know what to do if you are bitten by one of these animals. The wonders that surround us are numerous so go and explore as many as you can but remember that while many of them are safe there are also those could be dangerous so prepare yourself with as much knowledge as possible before you go.

References

Brennan, T. C. (2008). Lizards of Arizona. Retrieved from http://www.reptilesofaz.org/lizards.html

Beck, D. T. (2004, July/August). Venomous Lizards of the Desert. Natural History Magazine, Inc., 32-37, doi:210633026

Freedman, B. (2008). Gila Monster. In K. L. Lerner & B. W. Lerner (Eds.), The Gale Encyclopedia of Science (4th ed., Vol. 3, pp. 1949-1950). Detroit: Gale. Retrieved from http://go.galegroup.com/ps/i.do?id=GALE%7CCX2830101050&v=2.1&u=uphoenix&it=r&p=GVRL&sw=w&asid=d229e4554a35a1d3423757b2bee6aab6

Campbell, G. E. (2007). Gila monster ungrateful: Severe pain, nausea, weakness, tremors followed rare bite. McClatchy - Tribune Business News. Retrieved from http://search.proquest.com/docview/462082426?accountid=458