Understanding Reptiles

This part of my guide for writers will help you in understanding reptiles, including the different types, their physiology, unique features and how they live. Reptiles have a number of things in common that the majority of other species do not have. That said, there’s a huge variety of species of reptile and each is quite unique. I will cover the most common species known in detail.

The aim is to arm you with the information you need to write about reptiles confidently, and I will direct you to more detailed sources of information where appropriate. While this section doesn’t cover mythological creatures like dragons, it can be used in the creation of your own fictional creatures.

So read on to learn all about this fascinating group of animals!

Taxonomy

The taxonomy of reptiles is complex. They are in the phylum Chordata meaning they have a spine. The class is Reptilia obviously meaning reptile. The taxonomy is more complex but it’s easier to break them down into four distinct groups:

  • Chelonians: tortoises and turtles. As a general rule tortoises are land dwelling and turtles are aquatic
  • Lizards: typically quadripedal (four limbs) but limbless lizards exist
  • Snakes: limbless reptiles that use venom or constriction to kill prey
  • Crocodilians: aquatic reptiles that are typically ambush predators

Among these four classes, there is a huge range of species with unique adaptations and ecology. There is a fifth class, the tuatara, which is lizard-like but is from a separate order and is the only surviving species of it’s order. The tuatara is native to New Zealand and the name is from the Māori language, meaning “peaks on the back”. Due to this, they are considered living fossils.

Cold-Blooded

Most people ‘know’ that reptiles are cold-blooded. This term is not quite accurate, but it is easier to understand. Ectotherm is the more accurate term, and it means the animal does not produce heat internally through metabolism. Instead they rely on heat from the environment to maintain the appropriate body temperature. This means they show behaviours such as basking in sunlight, or seeking shade to adjust their temperature.

The term poikilothermic means variable temperature, which includes most ectothermic species and reptiles are defined by this term. They need to vary their body temperature for different metabolic functions in their body. They can slow down metabolism by reducing their temperature, such as during hibernation. Another strategy used by most carnivorous reptiles is ambush predation rather than chasing down prey. All of these things allow poikilothermic species to be extremely energy efficient.

Eggs and Reproduction

Most reptiles lay eggs of some kind, with a yolk sac providing all the nutrients for the growing embryo. The term for this is ‘oviparous’. A number of reptiles are ‘ovoviviparous’ which means they produce eggs but retain them inside until they hatch or just before hatching. For example, all boas and most viper species do this.

Asexual reproduction has been recorded in a few reptile species. This is through a process called ‘parthenogenesis’ where a female can produce fertile eggs without mating, and the offspring are essentially clones of the parent. Komodo dragons in captivity are capable of this process.

Some reptiles exhibit temperature-dependent sex determination, where the incubation temperature of the eggs determines the sex, instead of chromosomes. It is most common in turtles and crocodiles.

Reptile Defenses

Camouflage

Camouflage is an extremely common tactic, the wild natural colouration of most reptiles allows for them to hide in their environment. Reptiles are capable of remaining perfectly still for long periods of time as well, which aids in avoiding detection. Venomous species like the gila monster and coral snake have bright colouration as a warning. Other species have threat displays, like rattlesnakes using specialised scales on their tails to make noise. Contrary to popular believe, the chameleon’s ability to change colour isn’t just for camouflage, but also a way of communicating feelings and mood.

Scales and Armour

Reptilian skin is made up of keratin scales and is tough and inelastic. Snakes have thick scales covering their bodies. Lizards have thick skin, and their scales may have protrusions for added protection, such as in the bearded dragon. Crocodilians are much the same with thick tough scales. Chelonians have thick scales on their limbs, and their shells are made up of even tougher keratin scutes that overly their modified rib-cage to make a solid protective housing. The carapace is the top part, and the plastron is the bottom. Some species even have hinges that allow them to close the shell completely, such as the box turtle.

Autotomy

Autotomy means to remove part of ones own body. Some lizards are capable of tail autotomy, where they can amputate their own tail in a bid to escape a predator. The tail moves around on its own for a while, and is intended to distract the predator so the lizard can flee. Specialised muscles within the tail allow this, and most species can regrow the lost tail. Species that can do this include iguanas, leopard geckos and crested geckos.

This is a quick rundown of the typical features of reptiles. I hope it gives you a bit of an idea of how they work. I will go on to cover each class of reptile in more detail with specific physiology, behaviour and other useful information. Let me know if you have any questions at all.