Reptile Characteristics

What are the features of all reptiles? What are the reptile characteristics that make them unique?

Reptiles are more than just snakes. In fact, reptiles roamed the earth along side the dinosaurs! But you might ask, aren’t all dinosaurs reptiles?

There is actually quite a lot of debate and nuance regarding the reptile vs. dinosaur classifications. Whether historically we say that dinosaurs are reptiles or that non-avian dinosaurs aren’t reptiles, is a subject for another article. 

In this article we’re going to talk about modern day reptiles.

The Four Orders of Reptiles

Order Characteristics & Features
Squamata
Nearly 7,000 species of lizards and snakes which have skin with scales that are periodically shed. Lizards have five toes on both their front and hind limbs while snakes are limbless with hinged jaws.
Crocodylia
There are 22 species of crocodiles and alligators. They have four-chambered hearts as compared to other reptiles which have only three chambers. They also have extended jaws, five toes on their front limbs and four on their back limbs.
Testudines
Turtles (includes tortoises) are comprised of more than 250 species. Their bodies are encased in shells made of bone. They have sharp jaws without teeth. This includes tortoises and sea turtles.
Rhyncocephalia
One species of reptile native to New Zealand. They are the only survivor of the ancient branch of reptiles.

Serpentium

The modern day word “reptiles” comes from the Latin serpentium, which comes from “serpō” (crawl or creep).

Where Do Reptiles Live?

Reptiles live on every continent except Antartica. There are many turtles that live in the ocean, some of which are enormous. Other turtles though, live on land. 

Lizards are terrestrial and their habitats range from rainforests, deserts, jungles, cities, town, and mountains! 

They inhabit treetops to underground burrows. Snakes also live in a number of habitats; some snakes are even aquatic!

Crocodiles and alligators live in and around swamps in both fresh and saltwater. 

Reptile Characteristics & Features

  • Reptiles are vertebrates; they have backbones
  • Reptiles are ectothermic or cold-blooded; meaning that they cannot control their own body temperature. They need to regulate temperature through interaction with their environment. 
  • All reptiles produce eggs. Most reptiles lay hard-shelled eggs, but there are a few that have live births. 
  • All reptiles have scales. Scales (or scutes) are small plates that form reptile skin. Turtles and tortoise shells are made of scutes which are similar to scales but they are bony and develop deeper than skin level than scales do. 
  • Both scales are scutes provide protection for reptiles. 
  • Reptiles shed their skin as they grow. Even turtles and tortoises “shed” or peel (molt) their shell in a similar way the snakes and lizards do .

Reptiles vs Amphibians

Reptiles

  • Breathe through lungs
  • Can reproduce on land
  • Their legs are positioned under their bodies
  • Leathery, watertight eggs
  • Skin is also watertight
  • Internally fertilize eggs

Amphibians

  • Breathe with gills, skin, or lungs
  • Reproduce in water
  • Their legs are positioned on the sides of their bodies
  • Gelatin-like eggs, not watertight
  • Skin is smooth, not watertight
  • Externally fertilize their eggs

Ectothermic (Cold-Blooded)

Reptiles are considered cold-blooded as they do not have any means of self-regulating their body temperatures; they are dependent on their external environment to raise or lower their temperature. 

When the environmental temperatures are too warm, reptiles will seek shade and cooler temps underground or soak in water to lower and regulate their temperature. Likewise, reptiles also will bask in the sun to raise their body temperature. 

Being cold-blooded, or unable to self-regulate their temperature, also means that reptile metabolism increases or decreases with body temperature. The warmer a reptile is the more active and faster their metabolism is. The cooler a reptile’s temperature, the slower its metabolism and the less active it will be. 

Amniotes

Reptiles are amniotes meaning that their young undergo embryonic (fetal) development within an amnion or membrane sac. 

While all reptiles are amniotes, most are also oviparous or egg-layers. 

Oviparous

The majority of reptiles are oviparous; lay hard-shelled eggs that develop and hatch outside of the body. There are some reptiles however that are viviparous (young develop inside the mother’s body resulting in live birth).

Scales and Scutes

One of the distinguishing visual differences between reptiles and other animals are reptiles’ scales or scutes. 

Scales

Reptile scales are small, hard plates made of proteins that develop from the outermost layer of skin called the epidermis. 

Scutes

Scutes are similar in appearance and function to scales but are bony structures that develop from a deeper layer of the skin called the dermis. Turtles, crocodiles and alligators all posses scutes instead of scales. 

Both scales and scutes provide reptiles protection and prevent the loss of water.

Scales and scutes can very dramatically in size, shape and color. Many reptiles depend on these body structures for not only protection but also use them for territorial displays and courtship behavior

Breathing Through Lungs

Reptiles breathe air through their lungs although, different ways in which this breathing is implemented depends on the reptile. 

For example most lizards breath using the same muscles with which they run, resulting in their having to hold their breathe while they’re in motion. Crocodiles however have stronger and more flexible diaphragms allowing them to breathe while moving. 

Four-Legged Vertebrates

But What About Snakes?

All reptiles are tetrapods (four-legged animal) or are descended from four-legged animals (snakes). Reptiles are vertebrate animals (having a backbone that runs the length of their bodies) just like birds, fish, and mammals. Evolutionarily speaking reptiles are intermediates between amphibians and mammals. 

Conclusion

Reptiles are without a doubt unique and have distinguishing features that set them apart from the rest of the animal kingdom! 

These reptile characteristics; the features of all reptiles, are what makes them incredibly special!

reptile characteristics the features of all reptiles

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