Reptiles: characteristics and examples
Reptiles are vertebrate animals belonging to the Kingdom Animalia, Philo Chordata and Reptilia Class.
In evolutionary history, reptiles were the first vertebrate animals to conquer the terrestrial environment.
They are examples of reptiles: turtle, jabuti, turtle, snake, snake, alligator, crocodile, chameleon, iguana and lizard.
Get to know the main characteristics of the reptile group:
The body of reptiles is formed by head, neck, trunk and tail.
They have two pairs of locomotor limbs, each with five fingers finished in claws and legs reduced in some lizards but absent in others, like snakes.
They can be crawling animals or swimmers, like sea turtles that have oar-shaped legs.
The skin is dry and resistant, covered with scales of epidermal origin, which makes it keratinised and practically impermeable.
However, some animals, such as turtles and jabutis, may also have bone plates of dermal origin.
Reptiles are pecilothermic animals, i.e. they are unable to keep their body temperature constant. Therefore, they need the heat of the environment to regulate their body temperature.
This condition limits the location of their habitats to the tropics and subtropics of the planet, where temperatures favour their metabolism. That is why we do not find reptiles in Antarctica.
Most reptiles are oviparous. Only a few snakes and lizards are ovoviviparous.
They have internal fecundation, where the male introduces the sperm into the body of the female.
The development of the embryo takes place inside the eggs, which are coated with corneal or calcareous shells.
This characteristic protects the embryo from desiccation, important for the conquest of the terrestrial environment.
The egg has the following embryonic attachments: amnion, corium, yolk sac and allantoid.
When the chicks are born they resemble adults, because the development is direct.
Digestive system and feeding
The digestive system is complete. They have mouth, pharynx, esophagus, stomach, intestine and cloaca. In addition, they have liver and pancreas.
Most reptiles are carnivores. A few species are herbivorous and omnivorous.
Some reptiles, such as caimans and matamatá, are predatory animals and occupy the top of the food chain.
The circulation is closed, double and complete.
The heart of snakes and turtles has two atria and an incompletely separated ventricle. While crocodilians have two atria and two well-defined ventricles.
Reptiles have lung respiration. The lungs present pulmonary alveoli making gas exchange efficient.
The olfactory organ of reptiles allows them to taste and smell and most reptiles are able to hear sounds.
Vision is not privileged, but the eyes have eyelids and nictitating membrane to protect them when submerged.
When they are on land, they are hydrated by tear glands, hence the expression "crocodile tears", as those animals "cry" frequently.
Snakes have the loreal fosseta, a hole between the eye and the nostril with a thermoreception function.
There are more than 7000 known species, subdivided into four orders:
- Body covered with corneal plates.
- Presence of four short legs and a tail.
- Large and sharp teeth.
- Heart with four completely separated cavities.
Order of Rhynchocephalia
- Divided into Lacertilium (lizards) and Ophids (snakes).
- The lizards have four legs and the snakes are apexes, i.e. without limbs.
- Some snake species are venomous animals.
- Presence of bone armour (hoof or shell), which provides protection to the body against mechanical shocks and attacks by predators.
- Absence of teeth and presence of a beak with corneal blades, allowing the capture and cutting of food.
- The dinosaurs, belonging to the Dinosauria superorder, belonged to the reptile class.
- Brazil is the fourth country in the world with the largest number of reptile species.
- Herpetology is the branch of biology that studies reptiles.