by Stevie Kennedy-Gold
The start of April only means one thing – pranks galore thanks to April Fools Day! Ok, ok, I realize that’s not necessarily true as April also marks that spring has sprung, many small critters are emerging from their hibernations, and we celebrate, among other things, Earth Day and Arbor Day. But we can all agree that April usually starts with a load of laughs, some fibs, and some fools. In the animal kingdom, however, fooling isn’t regulated to one day. In fact, many amphibians and reptiles rely on their ability to fool both predators and prey to survive.
Masters of Disguise
One of the oldest tricks in the book when it comes to fooling another is to transform to look like someone, or something, else. Although herpetofauna lack access to theatrical wardrobes teeming with makeup and outfits, they evolved behaviors and physical attributes that allow them to imitate other things. The gopher snake (Pituophis catenifer, Fig. 1), for instance, is a totally harmless colubrid species found across the western and middle United States and into Canada. They are beautiful animals, having splotches of gold, reddish-brown, and black along their bodies, and, due to these colorations, are often mistaken for rattlesnakes. What’s more, when spooked, gopher snakes tend to flatten their heads, coil into a strike position, and quickly sway their tails to and fro, a rattlesnake imitation that includes a realistic sound component when it occurs in dry grass. Most snakes are solitary animals and prefer to avoid conflict and avoid expending energy in get-away attempts, so scaring away potential predators through imitation is preferred over fighting and biting. Often times, this imitation works, and potential predators leave the gopher snake alone.
Predictably, snakes are not the only masters of disguise. Many frog species have unique morphological features that allow them to resemble other items in nature. The dark brown coloration and the points above the eyes of the smooth horned frog (Proceratophrys boiei) give it the appearance of a leaf (Fig. 2), allowing it to blend seamlessly into the forest floor and enabling it to both evade predators and ambush prey. Similarly, the entirely aquatic Suriname toad (Pipa pipa) looks like a dead leaf in the water due to its brown coloration and flattened body. Unless you’re an omnivore that prefers dead, low-nutrition leaves, the imitation tactics of these frogs improves their chances of survival and fools any prey items not clever enough to see past their disguises.
Not all imitations are meant to help an animal blend in. Sometimes, imitations serve “nefarious” intents. Although not apparent to an outside observer, alligator snapping turtles (Macrochelys temminckii) have a sneaky tactic to lure prey directly into their mouth. The tongues of these turtles evolved a vestigial piece of flesh, called a lingual lure, to protrude from the tip. Alligator snapping turtles will sit on the bottom of lakes and rivers and open their powerful jaws to reveal this pink bit of flesh. They then move the lingual lure around to make it look like a tasty worm, fooling unsuspecting fish right into their giant maws.
Spider-tailed horned vipers (Pseudocerastes urarachnoides), a species endemic to Iran, employ a similar tactic, albeit far more noticeably to the casual observer. Admittedly, the common name of this animal gives away the punch line, but, nonetheless, this species of viper evolved to have a unique tail. Much like how a rattlesnakes’ rattle is made of modified scales, the spider-tailed horned viper’s tail scales evolved so that the last few scales bulge out into a small bubble and the scales leading up to that bulge are heavily keeled, or ridged. While keeled scales are common in most species in the Viperidae family, the keeling on these tail scales is extremely exaggerated, making the scales look like long spikes, or even legs. When you combine the long, keeled scales with the large, posterior bulge, the tail of a spider-tailed horned viper actually looks like a spider! With the snakes speckled coloration allowing it to blend into surrounding rocks and a solid tail wiggle performance, the snake’s tail looks like a tasty spider lunch to unsuspecting birds… which then become lunch for the snake. Imitation is the best form of flattery… or maybe a reliable way to fill your belly!
Now You See Me, Now You Don’t
Whereas some reptiles and amphibians are the masters of disguise, allowing them to hide from predators or to lure unsuspecting prey, other herps use subtler bodily alterations to fool potential prey, predators, and even conspecifics (animals of the same species). Take, for example, color changes. Chameleons often come to mind at any mention of lizard color changes, but it is actually a misconception that chameleons perfectly blend into their surroundings, mimicking every leaf and twig in the background. In truth, chameleons and many other lizard species change colors to improve thermoregulation and to communicate with conspecifics – males signaling to females that they’re ready to mate, or relying on darker colors to demonstrate aggression. There are, however, some species of frogs that do lighten or darken their hue to blend into their surroundings. The gray treefrog (Hyla versicolor) is present across most of the eastern and middle United States and, as its name implies, is an arboreal species. Because it spends its time among green leaves and gray-brown tree trunks and branches, the gray treefrog has evolved the ability to change its body coloration so it can blend in perfectly with the substrate upon which it perches. If it is on a bright green leaf, the frog will shift to a green hue. Upon landing on a mossy rock or a lichen-crusted tree trunk, the frog will change to a more gray, blotched hue instead. One second, you can see the animal perfectly and, in the next, it has completely melted away into its surroundings.
Leaving Something Behind
Other herpetofauna use more exuberant tactics to evade capture. Unlike the camouflage-wielding gray treefrog, many lizard and salamander species will self-autotomize their tails to avoid being eaten. In these instances, the herp has already been seen (or, worse, caught by a herpetologist!) and needs a quick getaway. Running away without a distraction means that the predator will likely give chase and possibly capture the lizard or salamander. However, by self-autotomizing – or breaking off – their tails, these animals increase their chances of escaping. This drastic tactic is effective because the tail continues to wriggle around and move once detached from the animals’ body, making it a tasty and easy to grab meal! Many predators become distracted by the tail, leaving the lizard or salamander free to make its escape. Interestingly, this behavior is not strictly regulated to predator attacks. I witnessed a prolonged aggressive battle between two male western fence lizards (Sceloporus occidentalis), where one male lost his tail and, instead of leaving it to writhe on the ground and eventually decompose, the lizard (attempted) to make a hasty, grapple-filled retreat from the other male, all while holding his detached tail in his mouth! Although this seems morbid, it’s actually quite clever – tails require a lot of energy and resources to make, but then the appendage stores energy in the form of meat and fat. This male fence lizard was likely keeping hold of his old tail so that he could later consume it and regain those resources. And, don’t worry, most salamander and lizard species can regrow their autotomized tails (Fig. 3), an ability that many herpetologists take advantage of when we need tissue for genetic studies.
The list of herpetofaunal imitators and imposters, pranksters and fibbers goes on and on. Although these disguises and imitations aren’t meant to make other animals giggle and laugh as our April Fool’s Day pranks often do, these tactics allow these reptiles and animals to live another day, evade unwanted attention, or snag a tasty meal. But, at the end of the day, it really does beg the question… who is the bigger fool – the fool or the fool that falls for it?
Stevie Kennedy-Gold is the collection manager for the Section of Amphibians and Reptiles at Carnegie Museum of Natural History. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.
Carnegie Museum of Natural History Blog Citation InformationBlog author: Kennedy-Gold, Stevie
Publication date: April 14, 2021