All animals are classified or separated into special groups. Some of the
special groups include mammals, bird, fish, and reptiles. Other groups may
include cold-blooded, warm-blooded, vertebrates, invertebrates, and several
others. One group of animals that are known for their ability to live both in
water and on land are called amphibians. The word amphibian comes from a
Greek word meaning 'double life'.
There are about 7,000 species of amphibians living in the world surviving on
land and in water. They are an ancient group of animals that descended from
fish and first appeared about 340 million years ago. Some of them have legs
but others have no limbs. Amphibians have vertebrates or backbones just like
humans; however, amphibians are cold-blooded, and humans are warmblooded. They are not in the same animal group.
The most popular amphibians are frogs and toads such as the American
Bullfrog, Poison Dart Frog, American Toad, Tomato Toad, and many more.
Others include salamanders and newts. All amphibians have several common
characteristics too.
Their vertebrates are like human's but much smaller, and the backbone is
part of the exoskeleton, which means bones inside the body giving the
amphibian its shape and support. And part of their lives they live on land, but
they also live in or near water, and they use gills while in the water. The gills
help them breathe. Later, they will grow lungs and legs which will help them live
on land.
In addition, as it is cold-blooded, the amphibian's body temperature
changes with its environment. For example, if the air temperature is 58° F, the
amphibian's body temperature will be the same. Compared to humans, whose
body temperature always stays the same at 98° F.
Adult amphibians must stay near the water to keep their skin wet and they
do not drink water. Instead, water is absorbed through their skin. Another
characteristic of amphibians is their webbed feet for help when they need to
swim in the water.
Amphibians are hatched from eggs and look very different than their parents.
They have no legs when they are born but will later change, but as adults, they
will look like their parents. Though all amphibians have common characteristics,
frogs and toads lose their tails as adults, but salamanders keep their tails when
they become adults. They look like lizards without scales, and if they lose one of
their limbs, it will grow back or regenerate.
Following birth, amphibians look like fish and nearly all go through a
transformation or change called metamorphosis. For example, a frog hatches
as a tadpole with a tail and gills; becomes a tadpole with two legs; develops
four legs and a long tail; then becomes a froglet with a short tail; and then
finally becomes a full-grown frog.
1) Amphibians are descendants of which of the following animals?
A: Fish
B: Birds
C: Snakes
D: Worms
2) An amphibian's prey includes which of the following?
A: Beetles
B: Worms
C: Spiders
D: All the above
3) If the temperature of the air is 71° F, what is the temperature of an amphibian's
body?
A: 98.6° F
B: 71° F
C: 58° F
D: It may vary
4) During metamorphosis, frogs are froglets with short tails, which of the following
is the next step?
A: Becomes a tadpole with two legs
B: Develops four legs
C: Becomes a full-grown frog
D: Develops a long tail
5) Which of the following best defines exoskeleton?
A: A skeleton on the outside of a body giving an amphibian shape and support
B: A skeleton on the inside and outside of a body giving an amphibian shape and
support
C: A skeleton on the inside of a body giving an amphibian shape and support
D: A skeleton used by an amphibian during metamorphosis.
6) Which of the following statements is TRUE?
A: All amphibians will look like the parent when they are born
B: Amphibians are different than parents throughout their whole life
C: Amphibians look like only one parent when born
D: When born, amphibians look very different than their parents