Amphibian Concept
They are animals with two ways of life: Aquatic when they are tadpoles and when they are adults they are terrestrial.
Characteristics
Despite their different appearances, these animals have several similarities:
- They have moist skin, without scales;
- They have two pairs of legs;
- They are oviparous;
- They undergo metamorphosis, that is, the process of changes in the structure of an organism during the transition from the larval stage to the adult stage.
See the development of a frog
- 1. Fertilized eggs;
- 2. Tadpoles are born;
- 3. The hind legs appear;
- 4. The front legs grow;
- 5. The cause atrophies and the frogs begin to breathe through lungs;
- 6. Adult frog;
In the larval stage, they breathe through gills, when they become adults, they breathe through the lungs and through the skin.
They have a tube-shaped digestive system that begins in the mouth. The mouth is very wide, forming a large cavity internally. In the upper jaw there are small teeth that are used to grasp prey and not to chew. Your tongue is attached to the front of your mouth. That's why frogs are excellent insect hunters.
The digestive tube is continued by a pharynx, which communicates with a short and wide esophagus. The final portion is the large intestine that opens to the outside of the cloaca.
The heart of these animals has three chambers: Two atria or atria and one ventricle. In the ventricle, a small amount of venous blood mixes with arterial blood; They have sense organs.
In the frog these organs are:
The eyes are protected by three eyelids: upper, lower and transverse. This last one, called nictitating membrane, has the function of moistening and lubricating the eyes, keeping them lubricated.
