All amphibians belong to the subphylum taxon vertebrate. It is also said that the transition of amphibians from the land into the water is incomplete, this is because amphibians usually in the area of aquatic environments. The reason why the amphibians live in an area which is close to the aquatic environment is that in order for the amphibians to get air from the terrestrial environment, they have to adapt first, even though they have lungs and gills. The transition which usually occurs in amphibians is that of from aquatic to terrestrial environment.
The evolutionary relationship of the amphibians does re-occur again and again in each generation. The re-occurrence takes place in this way, frogs leave their eggs hanging around the plants in water, the eggs then hatch by themselves in the water and the young eggs develop into the adult and head towards the land. In this way the frog which is adolescent moves into the land. When they reach sexual maturity, the adult frog then goes back into the water.
Amphibians are organisms which are adapted to the wet environment. The wet environments which are necessary for amphibians include both arid and semi-arid environments. The main reason of why the amphibians require water is that, in water is where the eggs are laid and hatched. Therefore without water on the terrestrial environments means that amphibians cannot adapt to the life on the land.
Water is the most important requirement of the amphibians in order to adapt on land, but algae on the other side is also important. This is because after the eggs have been hatched, they remain hanging in those algae. The young tadpoles also get their food in the algae plants. Therefore by doing so they end up forming the symbiotic relationship, which is the living together of two living organisms without harming each other.
Amphibians such as the frogs have failed to adapt fully on land, this is because other reptiles have already developed the common early waterproof skin which contains the egg in the shell. Another reason of failure to adapt on land is that amphibians also failed to adapt on the warm, dry environment which is found on dry land. Early reptiles, animals and other organisms were succeeding in their adaptations on the land. Another which can also plays an important role in the failure of amphibians to adapt on the land is the low biomass on the land because only the minority of the organisms manage to adapt and survive on land. Other factors such as population growth, pollution, diseases and land degradation are some of the limiting factors which play a role in the majority of amphibians not to be found on the land as compared to the aquatic environment.
It is also said that the first organism which evolve from the ancestors of the fish is amphibians. They evolve in the period of the late Devonian between 360-370mya. Even though the amphibians evolve in the above mentioned period, frogs, caecilians and toads are the only three groups which remain of the ancient amphibians. But nowadays amphibians are found everywhere on the earth where there is availability of the water.
Wikipedia contributors. Amphibian [Internet]. Wikipedia, The Free Encyclopaedia; 2006 May 09, 00:20 UTC [cited 2006 May 09]. Available from: http://en.wikipedia.org/wiki/Amphibian
Wikipedia contributors. Chordata [Internet]. Wikipedia, The Free Encyclopedia; 2006 May 08, 12: 15 UTC [cited 2006 May 09]. Available from: http://en.wikipedia.org/wiki/Chordata
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