In Latin the word amphibian has a peculiar meaning, it literally refers to “two lives”. This is a distinctive feature of these animals, capable of adapting and carrying out their biological functions in two different ecosystems: the terrestrial surface and aquatic areas. However, let us go a little deeper into the meaning of amphibian.
Amphibians are part of this great family of living beings catalogued as vertebrates (they have bones, that is to say, an internal skeleton) anamniotas (their embryo develops in four different envelopes):
the chorion, allantoid, amnion and yolk sac, creating an aqueous medium in which it can breathe and feed), tetrapods (they have four limbs, ambulatory or manipulatory) and ectothermal (they have a variable body temperature).
They undergo a period called metamorphosis (a transformation experienced by certain animals during the stage of biological development that affects their morphology as well as their functions and lifestyle). Among the most notable changes experienced is the passage from gills (novels) to lungs (adults).
Types of amphibians
Within this large family of amphibians, we can make a small classification based on three orders: anuros, caudados or urodelos and apodos or gimnophiona.
Anurans are some types of amphibians that are grouped to all those amphibians that we know as popularly as frogs and toads. Be careful, the frog and the toad are not the same species. They are grouped together by their morphological and behavioural similarities.
The urodelos are other types of amphibians are differentiated by having a long tail and an elongated trunk. Their eyes are not excessively developed and they are covered by a thin skin. Here we find newts, salamanders, proteans and mermaids.
Finally, there are the types of amphibians ápodos, which are the most peculiar of all due to their appearance. They are very similar to a worm because they do not have limbs and their body is rather elongated.
Characteristics of amphibians
As we said earlier, amphibians are vertebrate animals, and they have the “privilege” of being the most primitive of this class of animals that inhabit planet Earth. They are said to have been present for about 300 million years, almost nothing!
They have four limbs: two front and two rear. These extremities are known by the striking name of quirido. The quirido is characterized by a morphology similar to the hand of a human person, with four fingers on the front legs, and five on the hind legs. Many other amphibians also have a fifth tail-like extremity.
Being cold-blooded living beings, their body temperature depends greatly on the environment in which they find themselves, since they cannot regulate their internal heat. This is one of the causes of force majeure that has led them to adapt to life in the water and on land. These two systems help them to avoid excessive heating or cooling of their body.
They are oviparous because they are born from eggs. The female is in charge of depositing these eggs and always does so in an aquatic environment, which is why young specimens have a respiratory system with scales.
The skin of these organisms is permeable, being able to be crossed by diverse molecules, gases and other particles. Some species are able to secrete toxic substances through their skin as a defence system against external dangers.
Even if we focus on their skin, it should be noted that this is wet and unpopulated scales, unlike other types of animals that do carry them. This circumstance allows them to correctly absorb water and, consequently, oxygen.
On the contrary, it makes them very vulnerable to dehydration processes. If an amphibian is in a low humidity environment, its skin will dry quickly, which can cause serious problems and even death.
These animals have a circulatory system whose main piece is a tricameral heart composed of two atria and a ventricle. Their circulation is closed, double and incomplete.
The eyes are usually bulky and, rather, bulging, which gives them a large field of vision very appropriate when hunting their possible prey. There are exceptions such as newts.
Although it may seem that they do not, amphibians do have teeth, although these are scarce. Their function is to help hold food. The tongue also becomes a perfect instrument for capturing other small animals. They have a tubular stomach with a short large intestine, two kidneys and a urinary bladder.
Examples of amphibians
Currently, there are about 3,500 species of amphibians catalogued. However, scientists, in their estimates, predict that the total number may be around 6,400.
When we think of amphibians, the image of a frog or a toad always appears in our heads, but we also have other animals such as newts and salamanders.
These are just a few examples of amphibians, although, logically, there are many more:
Anderson Salamander (Ambystoma andersoni)
This type of salamander is also known as ajolote or achoque purépecha. It is an endemic species, that is to say, that only exists in a certain place. In this case, it only lives in the Zacapu Lagoon, located in the state of Michoacán (Mexico).
It is mainly characterized by having a rather grumpy body, short tail and gills. Its orange or red color, added to its black dots that extend along its entire body surface, makes it not go unnoticed.
Marbled newt (Triturus marmoratus)
This animal is mainly located in Europe, specifically in the north of Spain and eastern France. It has a greenish colouring accompanied by very striking greenish tones. In addition, its back is crossed by a vertical line of very peculiar red pigment.
Common Toad (Bufo bufo)
It is very common to find it in almost the entire continent of Europe and part of Asia. It prefers habitats made up of stagnant water, irrigation areas, etc. Perhaps, being so resistant to living conditions in unhealthy waters have made it one of the most widespread and known amphibians. It does not have bright colours, but its skin is more of a “brownish” tone, covered by several bulges in the form of warts.
Red Frog (Temporary Frog)
Like its relatives mentioned above, this amphibian has also made Europe and Asia its home. Although it prefers humid places, this frog spends much of its time out of the water.
It does not belong to a fixed color pattern, but each individual may have different colors. In spite of this, the brownish skin with small spots tends to predominate. The pointed snout is one of its signs of identity.
