 Skeleton
of Rana |
 Vertébrés
tétrapodes |
 Animales
vertebrados |
Thanks to photovisual.info website for allowing us to watch this photo.
| The morphology of frogs is unique among
amphibians. Compared with the other two groups of amphibians,
salamanders & caecilians, frogs are unusual because they lack tails
as adults and their legs are more suited to jumping than walking. The
physiology of frogs is generally like that of other amphibians, and differs
from other terrestrial vertebrates because oxygen can pass through their
highly permeable skin. This unique feature allows frogs to 'breathe' largely
through their skin. Because the oxygen is dissolved in an aqueous film
on the skin and passes from there to the blood, the skin must remain moist
at all times; this makes frogs susceptible to many toxins in the environment,
some of which can similarly dissolve in the layer of water and be passed
into their bloodstream. This may be cause of the decline in frog populations.
Many characteristics are not shared by all of the approximately 5,250 described frog species. However, some general characteristics distinguish them from other amphibians. Frogs are usually well suited to jumping, with long hind legs and elongated ankle bones. They have a short vertebral column, with no more than ten free vertebrae, followed by a fused tailbone (urostyle or coccyx), typically resulting in a tailless phenotype. |
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