amphibians (ancient Greek amphibium = double-leaved), also as amphibians are known to be cold-blooded animals and are considered the oldest taxon of terrestrial vertebrates. About 400 million years ago the first amphibians appeared in the geological era of Devon. Almost all amphibians undergo a so-called metamorphosis during their lifetime, which means that their shape changes. A simple example is the frog. From the fertilized spawn tadpoles develop first. In this context one speaks also of the larva form. With the weeks, the tadpole grows and turns into a frog in several steps. With the completion of the metamorphosis, the former form of larva has become a full-grown animal. From this point on, the amphibian is then in the adult stage (adult).
Most amphibians also change habitat with the completed metamorphosis. Tadpoles are pure water inhabitants with gill breathing. Frogs breathe over their lungs, which develop during the metamorphosis. For this reason, amphibians are the link, as it were, between aquatic and terrestrial species. The shore leave of the vertebrates presumably took place from a preform of today known amphibians by bony fishes.
The amphibians living today are divided into three orders:
Anura: u.a. Frogs, toads
salamanders: u.a. Newts, Grottenolm, Axolotl, Salamander
Caecilian: u.a. Siphonops Annulatus
Characteristics of amphibians:
Amphibians (Lurche) have some characteristics that are absolutely typical of this class of vertebrates. In particular, this includes the ability to metamorphosis, the presence of a cloaca, or the Poikilothermie. In individual cases, not all features listed here may apply to an amphibious species. For example, not all amphibians necessarily have venom glands or a particularly pronounced visual sense.
breathingAs a larva, respiration takes place via the gills, later in the adult stage via the lungs.
extremities: Amphibians have a total of four extremities (two front legs, two hind legs). In some species, the extremities appear in stunted form.
procreation: The fertilization of the eggs takes place outside in the water. This means there is no copulation, such as mammals.
poison: Many species of amphibians are endowed with venom glands on the skin.
perspiration: A small percentage of the oxygen needed can be absorbed through the skin of the amphibians.
cesspool: Amphibians have only one outlet for the urethra and anus, the so-called cloaca.
spawn: The larvae of the amphibians hatch from the spawn.
habitat: Amphibians can live both in the water and on land. Depends essentially on the developmental stage of amphibian.
metamorphosis: Amphibians undergo development (metamorphosis) from the larva to the adult animal. Most of the amphibian species turn from aquatic animals to endemic animals.
Poikilothermie: All amphibians are hotter. Your body temperature depends on the ambient temperature.
mucous glands: The skin of amphibians is permanently moistened by special mucous glands.
sensesAlmost all amphibians have a good sense of sight. They react particularly strongly to movement stimuli.
vertebrates: As a vertebrate, adult-stage amphibians have a spine.
List of amphibians:
Agama Toad, Axolotl, Fire Salamander, Frog, Gecko, Grottenolm, Tree Frog, Newt, Poison Dart Frog, Common Newt, Unke, Sand Lizard