Amphibians were the first animals that left the aquatic environment to colonize the terrestrial environment. However, they have never completely abandoned the aquatic environment and have a curious characteristic in the animal world: metamorphosis. Metamorphosis is a transformation by which they go from tadpole to adult, also changing their feeding or breathing.
What are amphibians and where do they live?
They are vertebrate animals that have a life cycle that alternates aquatic and terrestrial phases. The diversity of habitats in which they live is limited by this alternation of cycles and by the fact that their cold blood does not allow them to have a stable body temperature, which is why they are rare in very cold habitats. This is the reason why amphibians are not found living in Antarctica or the Arctic, although fossils have been found in these environments, for which there is evidence that in the past they were able to inhabit these environments.
We classify amphibians into three orders , which have different adaptive needs, so that although they can inhabit the same habitats, they sometimes live in different biomes. These three orders are:
- Order gymnophiona (or apodal amphibians): includes amphibians of great size and without limbs, such as caecilians or tapaculos. Apods are the worst cold-tolerant amphibians, which is why they almost always inhabit tropical and subtropical regions.
- Order Anura : amphibians that have legs (but do not have a tail), such as frogs or toads.
- Order Caudata : include salamanders, newts, and axolotls.
As we mentioned, amphibians that live in colder habitats are very rare . However, it is possible to find some, mainly anurans and salamanders . An exceptional case is that of the Siberian salamander, which lives in the northern part of Siberia (which we can see in the image below), or the forest frog, which lives in the northernmost area. North America (Alaska and Canada).
Since amphibians are cold-blooded animals, they show some adaptations to cold climates, such as hibernating under ice during winter or the presence of antifreeze substances inside the cells of their body.
The temperature in the taiga or boreal forest area is still cold, although somewhat less, so we find more species of amphibians. Some examples are the green frog, leopard frog, forest frog, American toad, blue- spotted salamander, common salamander or the Eastern newt.
The steppe, the savannah or the desert are dry biomes and not very favorable for the life of amphibians. This is because they represent areas with a lot of water scarcity and amphibians need fresh water to develop their larval stages. However, some anurans have developed adaptations to live in these climates and, in fact, in these parts of the world only anurans are found among amphibians.
Some examples of these adaptations are the retention of urine so as not to lose water and create an osmotic gradient that allows it to absorb water through its skin or to inhabit the subsoil, where they accumulate water, and leaving only to accumulate more water in times of rain. . Some species of this type of habitat are the red-dotted toad, the green toad, spur toad, Mexican burrowing toad or the corridor toad.
These are areas with more temperate climates and a greater abundance of fresh water, so it is not difficult to find amphibians. In these areas we find frogs, toads, salamanders and newts , such as the spur toad, common toad, green frog, San Antonio frog, common salamander or the marbled newt.
Amphibians of tropical or subtropical areas
These represent the areas closest to the equator and where amphibians are most abundant , because the high temperatures and rainfall make it a favorable habitat for these animals. As for anurans, frogs are more common than toads, many of which are poisonous or have striking colors, since frogs tolerate arid climates better. Some examples are the red-eyed frog or the arrowhead frog.
In addition, these areas are inhabited by many species of apodes or caecilians, although they are a very difficult group to study, since they live underground, on leaf beds or in soft soil.