Rose-bellied Lizard (Sceloporus variabilis) – Phil Hardberger Park
Photo by: Jessica Beckham (iNaturalist observation 45739254)
Fred Wills (retired from EAA) was the author of this piece. It has been updated is being maintained by AAMN Alexis Baum.
Animals with backbones are called vertebrates and are organized into several classes. We all recognize feathered birds and hairy mammals. But what is a reptile? Reptiles are vertebrate animals with scales or plates covering the body. Unlike birds and mammals, reptiles cannot maintain constant body temperature. They must move into or out of warm or cool areas to regulate their temperature. When an animal relies on external sources to regulate their core temperature, this is called an ectotherm. When the temperature is low, an ectotherm’s metabolism and ability to move slows down. WHAT ARE THE ADVANTAGES AND DISADVANTAGES OF BEING AN ECTOTHERM?
TYPES OF REPTILES NATIVE TO SAN ANTONIO AREA
Texas is home to a diverse group of reptiles that consist of lizards, snakes, turtles and crocodilians (alligators). When you explore the greenways and natural areas of San Antonio, you can find lizards, turtles, and snakes. While you may not see reptiles as you walk along the trail, know that San Antonio parks provide a home for this interesting group of vertebrates.
Common lizards in the San Antonio area include the Green Anole, Rosebelly Lizard, Texas Spiny Lizard, Texas Alligator Lizard, Common Spotted Whiptail, and Ground Skink. CAN YOU NAME ONE OF THESE LIZARDS THAT CAN CHANGE THE COLOR OF ITS SKIN TO BROWN? Like many birds and mammals, reptiles are predators. Small lizards like the Rosebelly Lizard, Common Spotted Whiptail, and Green Anole are insectivores. This means that they eat invertebrate animals such as insects.
Where do lizards live?
Different species of lizards are capable of living in a diverse range of habitats such as dry prairie, moist woodland, wetlands, and streams. Related species often divide the habitat through differing behaviors. For example, the smaller Rosebelly Lizard is found on the ground while the larger Texas Spiny Lizard primarily stays in the trees. The Ground Skink is a small, shiny, snake-like lizard that lives among fallen leaves and grasses. Its smooth scales and tiny limbs allow it to slip easily away if pursued by a predator.
Lizards and camouflage
Skin color in reptiles varies from dull browns and grays to striking bright green. Background-matching skin color or the ability to change skin color is an example of camouflage. Lizards use camouflage to hide from predators and to ambush prey. The brownish, mottled scales of the Texas Spiny Lizard allows it to blend into tree bark. This allows the Spiny Lizard to remain concealed while in the open. The Green Anole has the ability to change from green to brown. This often makes the animal nearly invisible among leafy trees and vines.
Color change communicates threats or sexual signaling
The male Green Anole lizard exposes a brightly colored dewlap that extends underneath his neck. The anole uses this bright color to attract females as well as laying claim to his territory. A male anole will also perform a series of push-ups to display his strength and intimidate any males from invading his territory.
Common turtles you will find swimming in San Antonio creeks, rivers, and lakes are Red-eared Sliders, Spiny Softshell Turtles, Texas River Cooters, Texas Map Turtles, and Common Snapping Turtles. Turtles are unique because of the bony shell that protects their bodies. The Spiny Softshell Turtle has a unique characteristic that causes it to stand out from the others. As its name indicates, this turtle has a soft shell that is flat and rubbery. Did you know that the backbone and ribs of turtles are fused to the bones of the shell?
For more information on turtles, please see the Talking Points article, “Turtles of San Antonio” authored by AAMN member Sal Scibetta. That article can be found here.
Snakes that are commonly found in San Antonio include the Texas Rat Snake, Rough Earth Snake, Texas Blind Snake, and Checkered Garter Snake. CAN YOU NAME ANOTHER SNAKE FOUND IN THE SAN ANTONIO AREA? Hint: This venomous snake can produce sound with its tail.
What do snakes eat?
A snake’s diet varies depending on its size. The diet of smaller snakes such as the Rough Earth Snake mainly consists of insects. Medium-sized snakes like the Checkered Garter Snake often eat frogs. While larger snakes like the Texas Rat Snake eats small mammals and birds. Some reptiles even live in the ground. A peculiar looking snake named the Texas Blind Snake lives in the soil and feeds on ant and termite larvae. The Texas Blind Snake is often described as a shiny earthworm and is capable of secreting a noxious scent that repels attacking ants.
What to do if you encounter a snake
The majority of snakes are non-venomous. If a person takes proper precautions, even venomous snakes are of little concern. To avoid potential problems, do not handle unidentified and possibly venomous snakes. Wear boots when you are off-trail and be aware of your surroundings. Do not put your hands or feet in places you cannot see and always use a light at night. Keep in mind that reptiles are ectotherms. On a cool morning, you will most likely find snakes basking in a sunny area to raise their body temperature.
For more information on snakes, please see the Talking Points article, “Snakes of South Central Texas” authored by AAMN member Sal Scibetta. That article can be found here.
Western Diamondback Rattlesnake (Crotalus atrox) – McAllister Park
Photo by: Jon (iNaturalist observation 23826809)
For more information for children see, Leapin’ Lizards.