Reptiles are a diverse animal group. In it we find the lizards, snakes, turtles and crocodiles These animals inhabit both land and water, whether fresh or s alty. We can find reptiles in tropical forests, deserts, grasslands, even colder areas of the planet. The characteristics of reptiles have allowed them to colonize a wide variety of ecosystems.
In this article on our site we will discover 10 characteristics of reptiles that make them extraordinary animals.
Classification of reptiles
Reptiles are vertebrate animals that derived from a group of fossil reptile-like amphibians called Diadectomorphs. These first reptiles originated during the Carboniferous, a time when there was a wide variety of foods.
The reptiles from which the current reptiles evolved are classified into three groups, depending on the presence of temporal openings (they have holes in the skull to decrease its weight):
- Synapsids: reptiles similar to mammals and that originated. They presented a single temporary window.
- Testudineos or anapsids: gave rise to turtles, they do not have temporary windows.
- Diapsids, are divided into two groups: archosauriomorphs, which include all species of dinosaurs, which gave rise to birds and crocodiles; and lepidosauriosmorphos, which originated lizards, snakes and others.
Types of reptiles and examples
In the previous section we have been able to know the classification of the reptiles that originated the current ones. Thus, today, we know of three groups of reptiles:
Crocodiles
Among them, we find crocodiles, alligators, alligators and alligators, and these are some of the most representative examples:
- American crocodile (Crocodylus acutus)
- Mexican crocodile (Crocodylus moreletii)
- American alligator (Alligator mississippiensis)
- Spectacled caiman (Caiman crocodilus)
- Black alligator (Caiman yacare)
Squamous or Squamata
They are snakes, lizards, iguanas and blind shingles, such as:
- Komodo Dragon (Varanus komodoensis)
- Marine Iguana (Amblyrhynchus cristatus)
- Green Iguana (Iguana iguana)
- Common Gecko (Tarentola mauritanica)
- Green Tree Python (Morelia viridis)
- Blind shingles (Blanus cinereus)
- Yemen chameleon (Chamaeleo calyptratus)
- Australian thorny devil (Moloch horridus)
- Ocellated Lizard (Lacerta lepida)
- Desert Iguana (Dipsosaurus dorsalis)
Chelonian
This type of reptile corresponds to turtles, both terrestrial and aquatic:
- Black Tortoise (Testudo graeca)
- Russian Tortoise (Testudo horsfieldii)
- Green Turtle (Chelonia mydas)
- Loggerhead sea turtle (Caretta caretta)
- Leatherback sea turtle (Dermochelys coriacea)
- Snapping Turtle (Chelydra serpentina)
Reproduction of reptiles
After reviewing some examples of reptiles, we continue with their characteristics. Reptiles are oviparous animals, that is, they lay eggs, although some reptiles are ovoviviparous, such as certain snakes, giving birth to fully formed young. Fertilization is always internal. The shell of the eggs can be hard or parchment.
In females, the ovaries are “floating” in the abdominal cavity and have a structure called the Müllerian duct that secretes the egg shell.
Reptile Skin
One of the most outstanding characteristics of reptiles is that in them there are no mucous glands in the skin to protect it, only epidermal scales These scales can be arranged in different ways: next to each other, overlapping, etc. The scales leave a mobile area between them, called a hinge, to carry out the movement. Below the epidermal scales we find bone scales called osteoderms, their function is to make the skin more robust.
The skin does not change in pieces, but in one piece, the shirt. It affects only the epidermal part of the skin. Did you know this information about reptiles?
Reptile respiratory system
If we review the characteristics of amphibians we see that breathing occurs through the skin and the lungs are not very septate, that is, they do not have many branches for gas exchange. In reptiles, on the other hand, this septation increases, causing them to make a certain noise when breathing, especially lizards and crocodiles.
Furthermore, the lungs of reptiles are traversed by a duct called mesobronchus which has ramifications where gas exchange occurs.
Circulatory system of reptiles
Unlike mammals or birds, the heart of reptiles has only one ventricle, which in many species begins to septa, although only in crocodilians is it completely partitioned.
In crocodilians, moreover, the heart has a structure called Paniza's orifice that connects the left part of the heart with the right. This structure serves to recycle blood when the animal is submerged in water and cannot or does not want to come out to breathe.
Digestive system of reptiles
The digestive system of reptiles is very similar to that of mammals. This begins in the mouth, which may or may not have teeth, continues with the esophagus, the stomach, the small intestine (very short in carnivorous reptiles) and the large intestine that leads to the cloaca.
Reptiles don't chew their food, so those that eat meat produce large amounts of acid in the digestive tract to promote digestion, also, this process can last several days. As additional information about reptiles, we can say that some swallow stones of various sizes because it helps them to grind food at stomach level.
Some reptiles have venomous teeth, such as snakes and 2 species of gila lizards from the Helodermatidae family (in Mexico). Both species of lizards are very poisonous, some salivary glands are modified and are called Durvernoy's glands. They have a couple of grooves to secrete a toxic substance that immobilizes the prey.
In snakes there are different types of teeth:
- Aglyph teeth: no channel.
- Opisthoglyph teeth: they are in the back of the mouth, with a channel through which the poison is introduced.
- Protoroglyphic teeth: they are in the anterior part and have a channel.
- Solenoglyphic teeth: only in vipers. They have an internal conduit. The teeth can move back and forth and are more poisonous.
Reptilian nervous system
Although anatomically the nervous system of reptiles has the same parts as the nervous system of mammals, it is much more primitiveFor example, the brain of reptiles does not have convolutions, which are the typical grooves of the brains and serve to increase the surface without increasing the size or volume of the brain. The cerebellum, responsible for coordination and balance, does not have two hemispheres and is highly developed, as are the optic lobes.
Some reptiles have a third eye, which is a light receptor, and communicates with the pineal gland, located in the brain.
Excretory system of reptiles
Reptiles, like many other animals, have two kidneys that produce urine and a bladder that stores it before it is expelled down the sewer However, some reptiles do not have a bladder and eliminate urine directly through the cloaca instead of storing it, this being one of the curiosities of reptiles that few know about.
Due to the way they produce urine, aquatic reptiles produce a lot of ammonia that needs to be diluted with the water they drink almost continuously. On the other hand, terrestrial reptiles, with less access to water, transform ammonia into uric acid that does not need to be diluted, so the urine of terrestrial reptiles is much thicker, pasty and white.
Reptile feeding
Within the characteristics of reptiles we find that they can be herbivorous or carnivorous Carnivorous reptiles can have sharp teeth like crocodiles, venomous teeth like snakes or a serrated beak like turtles. Other carnivorous reptiles feed on insects, such as chameleons or geckos.
On the other hand, herbivorous reptiles eat a wide variety of fruits, vegetables and herbaceous plants. They do not usually have visible teeth but they do have a lot of strength in their jaws. They tear off the piece of food and swallow it whole, so it is common for them to eat stones to help with digestion.
If you want to know other types of herbivorous or carnivorous animals, as well as all their characteristics, don't miss these articles:
- Herbivorous animals - Examples and curiosities
- Carnivorous animals - Examples and curiosities
Other characteristics of reptiles
In the previous sections we have reviewed the different characteristics of reptiles regarding their anatomy, feeding and breathing. However, there are many other common traits in all reptiles, and here are the most curious:
Reptiles have short or missing limbs
Generally, reptiles have very short limbs. Some reptiles, like snakes, don't even have legs. They are animals that move very close to the ground.
Aquatic reptiles don't have long limbs either.
Reptiles are ectothermic animals
Reptiles are ectothermic animals, this means that they are not able to regulate their body temperature by themselves and depend on temperature medium. Ectothermy is linked to certain behaviors. For example, reptiles are animals that usually spend long periods in the sun, preferably on hot rocks. When they feel that their body temperature has risen too much, they move away from the sun.
In regions of the planet where winters are cold, reptiles hibernate.
Vomeronasal or Jacobson organ of reptiles
The vomeronasal or Jacobson's organ is used to detect certain substances, usually pheromones. In addition, through saliva, taste and olfactory sensations are impregnated, that is, the sense of taste and smell go through the mouth.
Heat-receiving nostrils
Some reptiles detect small differences in temperature, they detect up to 0.03 ºC of difference. These pits are found on face, have between one and two pairs or even up to 13 pairs of pits.
Inside each pit there is a double chamber separated by a membrane. If there is a warm-blooded prey animal nearby, the air in the first chamber increases and the membrane inside stimulates nerve endings, alerting the reptile to the presence of potential prey. To learn about them, don't miss this other article on "Animals that are prey".