Amphibians are vertebrates (animals with a backbone)
just like reptiles, mammals,
fish, and birds. Amphibians
can be separated from other groups because they have moist skin and their
bodies don't have scales, hair, feathers, or claws.
The word amphibian
comes from the Greek word 'amphibios' which means two lives: amphibians
have a larval stage and an adult stage that are usually very different
from each other. A good example is the frog when it changes from the
larval gill-breathing tadpole to the adult lung-breathing frog.
There are three
basic groups of amphibians. The first group is made up of frogs and
toads, the second is made up of salamanders and newts, and the third
is made up of worm-like animals that are found only in the tropics.
Amphibians are "cold-blooded" which means that their body temperature
is the same as the surrounding air, water, or soil. Some frogs can even
survive freezing temperatures. The frog's body produces a chemical that
acts like the antifreeze we use in cars. This chemical keeps the cells
alive during freezing temperatures.
In this expedition
I am researching the spring salamander.
The spring salamander is an amphibian. It is cold blooded
and it has smooth moist skin. It has no lungs and no claws. The
spring salamander usually lives near and in water. The spring salamander
must return to water to reproduce. Most
salamanders develop in a series of stages. They begin as an egg, then change
to a larva, next a juvenile, and finally the adult. Most North American
species have aquatic eggs and larva, while the juvenile and adult stages
are terrestrial, which means land dwelling.
The newly hatched salamanders are called larvae
and look similar to tadpoles. The larvae have external gills, tiny legs,
a tail and a mouth with teeth. Unlike the tadpole, the aquatic salamander
larvae are carnivorous and feed on tiny insects in the water. In several
weeks the larvae grow or changed into a young adult or juvenile.