Who are reptiles?
Approximately 6,000 species of vertebrates belong to the class of reptiles (Reptilia). Most of them are dry land animals and are divided into four orders: Chelonia, Rhyncocephalia, Crocodilia and Squamata. Estonian reptiles (five species) belong to the order of Squamata.
What do reptiles look like?
The appearance of reptiles that belong to different orders is different - it is either similar to a lizard, snake, turtle, or tortoise. We are not going to describe the appearance of the orders which do not live in our country (e.g. Chelonia and Crocodilia).The skin of all reptiles is dry, without glands and covered with plates called scutes of different size. These protect the body of the animal. The body of a lizard has a head, neck, body, and tail. There are poorly developed legs at the sides of the body. The head of a snake evenly becomes a body and finishes with a tail. Snakes have no limbs. Python living in South-Eastern Asia is the longest snake in the world. The length of it can be up to 10 meters. The crocodile living in South-Eastern Asia as well is the heaviest reptile weighing up to 520 kg. The smallest reptile, a lizard-like gecko in Haiti, is 17 mm long.
Where do reptiles live?
Reptiles are dry land animals. Although some reptiles live either temporarily or permanently in the water, it is not vital for reproduction and development. The reptiles are most numerous in warmer and drier places - deserts and semideserts.
How do reptiles move?
As lizards are not able to lift their body up to the limbs, they have to crawl using the help of limbs and tail. The snakes have three different ways of moving on land: lateral undulating, straight crawling, and side winding.
How do reptiles breathe?
All reptiles breathe through lungs. They breathe by means of muscles between ribs and stomach muscles.
What is the circulatory system like?
Reptiles have similar to amphibians three-chamber heart and systemic and pulmonary circulation. Reptiles are cold-blooded due to relatively slow metabolism.
What do reptiles eat?
Most reptiles are carnivorous and they swallow the prey whole. The use teeth only to hold the prey. Poisonous snakes use fang for self-protection and killing the prey. Lizards that live here mostly eat small invertebrates, snakes eat tiny mammals.
What are the main organs of senses of reptiles?
The senses of vision and smell are well-developed. They can distinguish well only moving objects in most cases. The squamata have an additional organ for smelling - Jacobson's organ. In order to smell snakes dart out the slender, forked tongue, pick up scent particles in the environment and press it up against two small hollows in the roof of the mouth - Jacobson's organ. Several reptiles use tongue as tactile organ as well. The majority of reptiles have poorly developed sense of hearing - they can only sense the vibrations of earth in most cases.
How do reptiles reproduce and develop?
Reptiles are bisexual, fertilization is internal. Even the reptiles that live in the water come to dry land to reproduce. The female lays eggs into a damp, warm place where the sun hatches the eggs. Reptiles do not have metamorphosis in the course of their development, young reptile hatchlings are similar to adult reptiles, they are only smaller in size. Few squamata are ovoviviparous (e.g. adder). The fertilized eggs of these snakes develop and hatch inside the mother, who then gives birth to live young.