Reptile Adaptations to Maintain Ambient Temperature

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Many reptiles rely on ambient environmental temperatures to maintain critical physiological processes. They are ectothermic tetrapods that lay shelled eggs on land and have lungs. Some are ovoviviparous; others are viviparous and reproduce sexually through internal fertilization.

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A lizard that rolls itself into a tight ball may protect itself from predators. It also enables it to absorb more heat from the sun.

Thermoregulation

Reptiles, which evolved from amphibians 350 million years ago, use a variety of behavioral and structural adaptations to regulate their body temperature. Unlike mammals and birds, which are endotherms, which produce their own internal heat, reptiles are ectotherms, which gain their body warmth from the environment. They are able to maintain their preferred body temperatures by basking in sunny places, finding shady spots or going underground to cool down.

The scaly skin of most reptiles, which covers a dense layer of protein called keratin, reduces water loss and is also a good barrier against bacteria and insects. This is an important evolution from their amphibian ancestors, which had wet skin.

As a result, reptiles do not require as much energy from their food to maintain their body temperature as endotherms. The ability to generate their own body heat allows them to eat less, which helps them conserve resources.

In addition to regulating their own body temperatures, reptiles have a variety of behavioral and morphological adaptations to allow them to escape notice or fight off enemies, reproduce, obtain food and adapt to their environment. Many of these behaviors and adaptations appear bizarre to the uninformed observer, and may be mistaken for signs of disease or injury.

For example, the garter snake (Thamnophis praeclarus) and other reptiles that spend much of their lives in the ground brumate by rapidly absorbing vapor from their own bodies, a process that is very effective at cooling the animal. The pit receptors of these animals are almost insensitive to steady temperature changes, although they are very sensitive to the rate at which the external temperature changes.

Tail Autonomy도마뱀분양

Caudal autotomy is a defensive behavior that allows some reptiles to drop their tails to distract predators or to escape from capture. Shed tails continue to wiggle after being dropped, creating the illusion that the animal is struggling and deflecting the predator’s attention away from the body or head. A variety of lizards, snakes, salamanders, and tuatara have this ability.

Until recently, it was believed that caudal autotomy evolved exclusively in lepidosauriformes (Reptilia: Squamata). However, recent research shows that early amniote taxa possessed the ability as well. Specifically, articulated caudal vertebrae from the Early Permian Richards Spur locality, Oklahoma, show that captorhinids, a subfamily of agamid lizards, possessed fracture planes in their caudal vertebrae that would have permitted them to shed their tails (Fig. 1).

While the presence of these fracture lines suggests that captorhinids were capable of caudal autotomy, the absence of these features in the skeletons of other agamid lizards from Richards Spur indicates that this defensive behaviour was lost in many phylogenetic lines. In agamids that have retained the capacity, this form of autotomy is referred to as intravertebral (IntraVB) autotomy.

In a laboratory-based predation experiment, Cooper and Vitt (1985) showed that scarlet kingsnakes (Lampropeltis elapsoides) directed attacks toward the tails of two species of juvenile skinks (Plestiodon fasciatus and Plestiodon laticeps), rather than the body or head. Interestingly, the tails of these species are conspicuously colored blue and were able to deflect attacks by diverting the predator’s attention.

Hiding Places

Reptiles often hide in secluded places to protect themselves from predators, scavengers and weather extremes. They also use these hiding spots to find food. For example, a snake can crawl into a small den to ambush worms and rodents that it would otherwise be unable to catch.

In nature, hides might include logs, piles of leaves and other debris or natural rock crevices. In a home setup, students can replicate these natural hides by using butcher paper, cypress mulch or hay. Alternatively, they can use their imaginations to create their own.

Closets, for instance, are a great place to hide for many reptiles because they provide tight spaces that offer relative seclusion and access to warm air. They are also a good choice because they usually have plenty of clutter where a snake can retreat without being noticed.

Encourage students to think about the different ways a reptile might adapt to its environment. Ask them to identify whether the changes they see are behavioral or physical. For example, a polar bear’s thick fur is a physical adaptation that helps it stay warm; on the other hand, a lizard that “plays dead” to avoid predators is demonstrating a behavioral adaptation.

Tail Displays

Many reptiles display a highly visible tail when grasped by a predator. This can be effective in distracting a predator away from the vulnerable parts of the body and allowing the animal to escape. Usually the tail will continue to wiggle vigorously in this mode of defence. There are even reports of monitor lizards striking at the eyes of aggressors with their tails.

Similarly, many reptiles whose tails are shed have the ability to regrow them without suffering damage. This is a very useful behavioural adaptation that occurs in all families of lizards, most salamanders and some rodents. The ability to regrow a lost tail is an indication that the loss was due to an attempt at defence rather than to injury or disease.

In some lizards, the tail may be waved in a brightly colored contrasting pattern as part of a threat display. This is common in coral snakes and ring necked snakes and can be effective in startling a potential attacker.

Some hognose snakes exhibit a dramatic death feigning behaviour that involves an exaggerated S-coil and loud hissing. If the animal is further harmed it will assume a pose with its head held in a limply open position and will begin to excrete urates and feces from around the mouth and cloacal area. This is intended to increase body size and intimidate a predator as the snake will be perceived as being full of food.