The Amphibian Body

Information about Amphibians: The Amphibian Body
What is fascinating about the amphibian body is the place it holds in evolution. They were the first vertebrates to have tongues, the first to have eyelids, the first ears, and less visible, but even more extraordinary are the nervous system and spinal cord.

Embryo
To start at the beginning we should consider the amphibian embryo. The first thing to note is that they don’t have shells, just a gelatinous layer that is not as strong as the protective membrane of higher vertebrates. The embryos are laid in water or somewhere moist, although a few rare amphibians give birth to developed specimens. Most of them produce a larvae like a frog’s tadpole, which rapidly develops into a full specimen.

Skin
The moist skin of the amphibian is common across the species, but it is the variation of skin types that is some of the most interesting information about amphibians. For example, some frogs actually have bone in their skin, and some caecilians have scales.

Heart & Lungs
The amphibian heart has three chambers, a left and right atrium and a ventricle. Most amphibians have paired lungs, but in caecilians the left lung is very small, and some salamanders have no lungs at all.

Skull
The flat skull of the amphibian cases just ten cranial nerves – the same number as fish. Extending from the skull’s maxillary bone are teeth. Information about amphibians often fails to reference that these branch-like teeth are attached to a fibrous tissue that allows the teeth to bend inwards.

Diversity of Body Movement
Despite these similarities in body type the amphibia class use their bodies for motion in a diverse manner. Whilst caecilians swim like fish, frogs have a stroke all of their own (the leg thrust swimming style of a frog results from its shortened vertebrae). On land too there are varying styles of movement, from the lateral diagonal movement of salamanders to the fold and extend “walk” of the legless caecilians.

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