Color Changers

 

Green Anole, Anolis carolinensis

Native to North America and most abundant from the Carolinas south to Florida, along the Gulf Coast, and as far west as the Texas Hill Country, the Green Anole (Anolis carolinensis) is a small to medium sized lizard with a long, pointed head, slender body, long tail, and toes with adhesive pads that facilitate climbing.  Arboreal in nature, it can also be seen on the ground and in areas with shrubs and vines at the edge of our moist forests.

Males are typically 15% larger than females, from 4.9 to 8 inches long, with about 65% of that length being tail. Males have a dewlap or throat fan that is three times the size of the females and is strawberry-red, while the females’ dewlap ranges from white to light pink.  Unlike males, females also have a prominent white stripe that runs along their spine.

Male Green Anole with dewlap extended

Strongly territorial, males will fight other males to defend their territory, and have even been known to fight their own reflection in mirrored glass. When a male sees a rival, he will compress his body, extend his dewlap, inflate a dorsal ridge, and bob his head to chase off the intruder.  If that doesn’t work, they will fight, especially during mating season. A male’s territory typically includes two to three females, and he will court a female by extending his dewlap and bobbing up and down, mimicking a push-up. 

Breeding begins in April and ends in late September, with females laying their first clutch of one or two eggs about a month later.  Females can produce an egg every two weeks during mating season, up to about ten eggs, and they are buried in a shallow depression in soft soil or leaf litter.  Eggs are incubated by the heat of the sun, and hatch in five to seven weeks, with the hatchlings left to fend for themselves.

What is most intriguing about these lizards is their ability to change color from bright lime green to dark brown, and while often called ‘American chameleons’, they are not true chameleons.  Their ability to change color is a result of three layers of pigment cells or chromatophores.  The first is the xanthophores which is responsible for yellow pigmentation, the second is cyanophores responsible for blue pigmentation, and the third is melanophores responsible for brown and black pigmentation.

Male Green Anole, brown color form

If one of the chromatophores is lacking due to genetics, color mutations can form, but are extremely rare in the wild. Blue-phased green anoles lack xanthophores, and yellow-phased green anoles lack cyanophores.  These color exceptions rarely live long, as they don’t provide the camouflage the green color does, which is highly useful in hiding from predators and hunting down prey.

Several factors contribute to the anole changing its color, including its mood, stress level, activity level, and even social signals such as displaying dominance.  Although claimed, evidence does not support color change due to camouflage or a response to background color, and it is even less clear if the color change is in response to temperature.  When stressed, during a fight for example, the skin behind their eyes may turn black and form postocular spots that resemble a small black mask.  

Regardless of the reason, no other lizard species in Texas is capable of such extensive color change.  With populations existing in even the largest of cities, these color changers are a fascinating part of our suburban landscape! 

Ancient Alligators

Texas Alligator Lizard

An ancient and widespread lizard family, Anguidae originated in the Triassic Period, over 100 million years ago.  Today there are 67 species recognized worldwide, with 8 found in North and Central America. Members of a large branch of the snake/lizard evolutionary tree that use their strong jaws rather than tongues to draw food into the mouth, Anguids reserve their hard, slightly forked tongues as chemosensory organs used to search for food, mates, and safe refuge.  

One subfamily within this group is called the alligator lizards, so named due to a vague resemblance to an alligator – a flat, wedge-shaped head, little neck definition, small, thin legs, and scales fairly large and shingled that barely overlap one another. These lizards shed in one piece, much like a snake, turning the old skin inside out as they crawl out of it.  They can also exhibit tail autonomy, the ability to shed their tail as a self-defense mechanism to elude a predator’s grasp and allow escape. While they have the ability to regrow their tail over a period of weeks or months, the new tail is often shorter and distinctly different in appearance from the original tail.

The only species of alligator lizard in Texas is the Texas Alligator Lizard (Gerrhonotus infernalis). Males have wider, more triangular heads than females, but both can grow up to 18 inches long, including their tail. Ground color ranges from light tan to dark brown, sometimes with a reddish cast, with 7 to 10 black and white flecked bands across the body. Newly hatched individuals look entirely different than the adults, with striking copper-colored heads and boldly banded black and cream bodies that resemble centipedes or millipedes.

Generally preferring moist areas of foothills to lowland limestone canyons, staying near springs, creeks, and streams, the Texas Alligator Lizard can even be found in suburban areas near these habitats.  They feed primarily on insects, spiders, and small vertebrates. However, they are secretive in nature, hiding under surface cover such as fallen tree limbs, forest undergrowth, and in rocky crevices.  They can be pugnacious when caught, often thrashing about and able to deliver a painful bite. When threatened by a predator, they may flee to water as they are good swimmers, or perform lateral undulation by folding in their thin limbs and slithering away quickly like a snake.   

Depending on the temperature or season, Texas Alligator Lizards may be active by day or night. In spring they are often arboreal as their tails are prehensile and assist in climbing, mating and feeding in vine tangles and other dense vegetation up to 9 feet off the ground.  Fall is mating season, with males fighting each other for the right to court a female.  Eggs are laid in clutches of 5 to 31 under rocks and in crevices between February and June, with females producing a second clutch if conditions are favorable. Unlike many other reptile species, females will remain with their clutch of eggs for the few months it takes them to incubate.

Texas Alligator Lizards are found throughout a few disjunct localities in the Big Bend region and in much of the Edwards Plateau, and are the largest limbed lizards in Texas. While their secretive nature means they often go undetected, it is a special treat to discover and observe one of these ancient alligators!

Tree Serpents

Rough Greensnakes are excellent climbers.

One of the most beautiful and harmless snakes in Texas is the aptly named Rough Greensnake (Opheodrys aestivus).  Its genus is derived from the Greek ophios meaning ‘serpent’, and drys meaning ‘tree.’  It has a 22 to 32 inch long and slender bright green body, which fades to yellow or yellow-green on the sides near its abdomen.  Common to the eastern two-thirds of Texas, this snake is also colloquially called grass snake, green tree snake, and vine snake, but it gets its most recognized common name from its dorsal or topside scales, which are rough or ‘keeled’, having a ridge down the center rather than being smooth.

Primarily arboreal, the Rough Greensnake is found in open deciduous forest, pastures, and suburban gardens, most frequently those adjoining a watercourse such as a creek, stream, lake, river, or upland ravine.  It climbs into bushes, shrubs, and trees, favoring those with horizontal rather than vertical growth, both for protection and to forage for food.   It hunts crickets, grasshoppers, and spiders, as well as caterpillars of butterflies and moths.  Rough Greensnakes are diurnal, and they sleep at night coiled up on branches of vegetation.  Active most months of the year except for December through February, they take refuge in the cooler months hiding under rocks, logs, or debris.

Rough Greensnakes are also called 'grass snakes', due to their
bright green bodies that fade to yellow on their sides and abdomen.

One of the most curious facts about this snake, and others in this genus, is that they turn blue shortly after death.  Yellow pigment combines with blue pigment to give the snake its vibrant green color during life, but when it dies, the yellow pigment breaks down quickly and only the blue pigment remains.  Rough Greensnakes may be confused with Smooth Greensnakes (O. vernalis), but the latter, while similar in color, is shorter in length, has smooth dorsal scales, and occurs only as a relict population along the Gulf Coast of Texas.

While Rough Greensnakes become active as early as March, they mate in June and July, with females laying clutches of eggs in the second half of summer, typically in a depression under a flat rock.  Incubation is short – only 4 to 24 days – since embryonic development begins while the eggs are still in the female’s body.  These snakes can be most active in August or September, when the young emerge and are foraging for food, often in grassy lawns.  Be alert for these snakes when mowing grass at this time of year, as they are beautiful, harmless, and beneficial creatures!   

Aquatic Apalones

Spiny Softshell Turtle

The genus Apalone is thought to come from the Greek apo meaning ‘separate’ and the Anglo-Saxon alone meaning ‘solitary’, as well as the  Greek apalos meaning ‘soft’ or ‘tender.’  All of these terms apply to the members of this genus, which is comprised of the softshell turtles native to North America.  Turtles of this genus exhibit marked sexual dimorphism, or the condition where the two sexes of the same species exhibit different characteristics beyond their sexual organs.

Females grow to twice the size of males, in terms of carapace or shell length.  In males, the claws on their front feet are longer than those on the back feet, enabling them to better hold on to the female while mating.  In females, the claws on the back are longer, for digging into sandbanks in order to lay her eggs.  Lastly, males have a thicker, stout tail that extends well beyond the edge of its carapace, but the female’s tail is relatively thin and barely extends beyond the carapace.  From a behavioral standpoint, the female is much more solitary, wanders more, and requires deeper water, while the male often congregates with juveniles in sandy shallows and while basking along exposed banks.

Spiny Softshell Turtle

There are two species of softshell turtle in Texas. The more common Spiny Softshell Turtle (Apalone spinifera) is found throughout the state, while the Smooth Softshell Turtle (Apalone mutica) is found only in parts of the eastern two-thirds of the state. The Spiny Softshell’s olive-gray or tan carapace is leathery and flat, and has small spines along the front edge, which explains its species name.  At home in rivers, lakes, ponds, and other bodies of water with muddy or soft bottoms, its spends its time feeding on aquatic insects, fish, and crayfish, basking or floating at the surface, or buried in soft, shallow substrates.  Its long neck and snorkel-like nose allows the turtle to breathe at the water’s surface without having to leave its buried location. Females typically grow to 22 inches, while males top out at 8.5 inches in length.

Smooth Softshell Turtle

The Smooth Softshell’s olive-gray to brown carapace is also leathery and flat, but lacks any spines, bumps, or projections.  This characteristic is reflected in its species name, which means ‘shortened’ or ‘docked.’  It also prefers bodies of water with soft, sandy bottoms, and basks on banks, logs, rocks, or under shallow water with its long nose exposed.  Primarily insectivorous, it will also consume vegetation and small invertebrates and fish.  Smaller than the Spiny Softshell, females grow to 14 inches and males to 7 inches in length.

One odd but amazing fact about softshell turtles is that they are believed to absorb 70% of their oxygen through their skin.  The other 30% comes from pumping water in and out of their pharynx or throats, which contain many tiny projections of tissue with small blood vessels that provide a huge surface area for oxygen absorption.  This adaptation allows them to remain underwater for several hours.  Now that’s one highly aquatic Apalone!