Who are amphibians?
early Devonian, about 370 million years ago, appear on land the first terrestrial vertebrates, derived from a group of bony fish, the Crossopterigi. These ancestors of today's amphibians (from the greek ANFI dual-bios = life) were anything but independent from the water but on land they had found a place "virgin" to colonize.
expand geological eras saw this strange group of fish that came to form two separate groups: Labirintodonti and Lepospondili. While i secondi, dopo essersi diversificati ed espansi, finiranno per scomparire nel mesozoico, i Labirintodonti daranno origine a moltissimi gruppi tra cui i Temnospondili (gli antenati degli anfibi attuali) e gli Antracosauri (gli antenati dei rettili, che compariranno nel carbonifero).
Fu proprio nel corso dell'era mesozoica che si originarono i tre ordini attuali degli anfibi:
- Apodi o Gimnofioni (cecilie & co)
- Caudati o Urodeli (salamandre, tritoni & co)
- Anuri o Saltatori (rane, rospi, raganelle & co)
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Below we summarize the salient features of the three orders, however, keep in mind that I'm referring to the systematic use of my time (then date) and will do well to explore these issues and other sources, in fact the current trend is to divide and fragment more and more families, genera and species ... the miracles of genetic engineering!
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Caudata
Among urodeles (about 360 species) enter the collective imagination ... those who have never seen, at least in photography, a salamander? However, these animals reclusive habits and cryptic environments related to "fresh", in fact, unlike the APOD is the anurans, it can be found in the tropics.
met their needs in climate, these amphibians have been able to exploit every ecological niche moving at ease on the ground, the leaves of trees or in the dark without end of the caves. Notable is the example dell'axolotl (tadpole neotenous dell'Ambistoma mexicanum) who decided to remain "child" for life!
Needless to describe their typical form "lucertoloide" and can not give you a few lines in the variety of shapes and colors that characterize this order.
Anura
undoubtedly represented the largest group (about 3500 species) and known. They have really colonized every niche on the planet including deserts the Thundra ee! Despite that, in adult form, are the most in percentage released from the water, the anurans are still inextricably linked water for their reproduction, very rare exceptions to those found in previous orders. Just
the larvae of the jumpers are known as "a tadpole" we have all seen at least once: these little balls with tails, and usually omnivorous feeding, makes the phenomenon of metamorphosis even more marked than in congeners whose larvae are already similar to adult.
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With approximately 170 species, the order of Gymnophiona colonizes currently living mainly in tropical areas underground. Exactly the subterranean habits mean that this order is flat base, this feature, combined with frequent color ring and eyes reduced or atrophied, makes these boots similar to the "big earthworms. The Apodi are widespread in America, Asia and Africa. All, except the kind that is Typhlonectes water as an adult, living their lives forever sunk into the ground. The
Cecilie have a characteristic sense organ: a tentacle that is normally stored in a special groove in the jaw, between the eye and nostrils. As with snakes in the respiratory activity is linked to only polmone destro, mentre il sinistro risulta atrofizzato. Nonostante l'aspetto "viscido" questi anfibi sono gli unici ad essere frequentemente coperti da piccole scaglie, utili a proteggere la pelle durante l'attività di scavo.
Le dimensioni di questi anfibi variano dai
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