This document provides an overview of amphibians including their characteristics, evolution, examples of different types of amphibians like frogs, salamanders, and caecilians. It discusses their anatomy, life cycles, habitats, defenses, diets, and more. Amphibians are defined as animals that develop outside the body, have glandular skin without scales, and can breathe through gills or lungs. They first appeared around 340-270 million years ago.

1. AMPHIBIANS
General Overview
Amphibians are animals that have the following characterizations: They develop out
side the body (eggs), have glandular skin without external scales,and resperation
(breath) occures through gills during development or in some cases into adulthood.
Some examples of amphibians include frogs, toads, salamanders, newts and
caecilians.
Evolution
Fossil records indicate that amphibians evolved form fish whose lobed fins became
legs. Gills adapted to that they may breath both above and below the surface of the
water. Amphibians first appeared some 340 to 270 million years ago, in the period
known as the Mississipian. To date, Amphibians can be found everywhere except in
Antarctica and Greenland.
Frog Watch
Due to their
glandular skin and
the fact that they
spend their critical
development
periods in the
wetlands,
amphibians are
good indicators as
to the health of our
environment.
The World of Amphibians
There are about
4,780 species of
amphibians
known to
naturalists, and
there may be 300
to 500 more that
have yet to be

2. discovered. In the United States and Canada there are only 250 species. The
world’s amphibians, most of which live in tropical areas, fall into three major groups
(called orders) with special characteristics.
Frogs
Frogs of all kinds (including toads) make up the biggest order of amphibians, with
about 4,000 species around the globe. North America north of Mexico has 100 frog
species. There are many kinds of frogs, including treefrogs, true toads, spadefoot
toads, and many others.
All About Frogs
Frogs have large eyes on the tops of their
heads. Many frogs have poison glands in
their skin. Most frogs and toads have
distinct songs or calls that are used by
males during the mating season. They
produce these calls by inflating a pouch in
the neck, called the vocal sac. Frogs have
short front legs and long, powerful hind
legs. They have four toes on their front feet
and five toes on their hind feet. Many frogs
have a hump in the middle of their backs,
where the pelvis connects the backbone to
the hind legs.
Little Grass Frog
Cane Toad © C. Allan Morgan
Salamanders
Salamanders are not nearly as common as frogs, totaling only some 410 known
species. North America, with
about 150 species, is the best
place in the world to see
salamanders.
Blue-spotted Salamander ©
Breck P. Kent

3. All About Salamanders
Salamanders have slender bodies and tails. Their legs are about equal in length.
Salamander skin is moist and usually smooth. Most salamanders have four toes on
the front feet and five toes on the hind feet. Most salamanders have vertical slits,
called costal grooves on their sides. Salamanders are usually both inconspicuous
and nocturnal—that is, they don’t bring attention to themselves and they prefer the
nighttime.
Caecilians
The third order of amphibians, the caecilians, does not occur in the United States or
Canada. Caecilians are burrowing wormlike creatures that live in tropical areas.
There are 165 species worldwide.
Record North American Amphibians
Largest frog: Bullfrog, 8"
Smallest frog: Little Grass Frog, 5/8"
Largest toad: Cane Toad, 9"
Smallest toad: Oak Toad, 1 1/4"
Largest salamander: Two-toed Amphiuma, 45"
Smallest salamander: Pygmy Salamander, 2"
Oak Toad © Phil A. Dotson -
Photo Researchers, Inc.
What Is an Amphibian?
Like birds, reptiles, mammals, and fishes, amphibians are vertebrates –- that is,
creatures with a backbone and an internal skeleton. Amphibians live part of their life
in water and part on land. Even those species that lay eggs on land start life in a
fluid-filled egg, breathing through gills.
Newts are brightly colored salamanders. These small amphibians are found in moist,
wooded areas in North America, Europe, and Asia.
Anatomy: On average, newts are about 3 to 4 inches (7.5 to 10 cm) long. They
have four legs; there are four fingers on each of the front legs and five toes on each
of the hind legs. The adult's color varies from deep green to brown on top, and the
underbelly is usually yellow with dark spots. Many newts have red spots along their
sides.
Life cycle: Like all amphibians, newts spend their lives near water because they
must return to the water to lay their eggs. Newt eggs are laid in the water. When
they hatch, they breathe with gills and swim. As they mature, they develop lungs for
breathing air. Some newts leave the water at this time and are known as red efts.

4. They are red-orange, but over about 2 to 3 years, they turn green. Then, they return
to the water to lay eggs and the cycle starts over again. Some newts do not go onto
the land, but remain in the water.
Diet: Newts eat insects, worms, snails, and small fish.
Salamander as Vital to Wetland Ecosystem
One reason the salamander is vital to the wetland ecosystem is its position in the
ecosystem's food web. Terrestrial salamanders eat earthworms, insects, slugs,
snails, beetles, and other small invertebrates. They even eat small mice! Sometimes
they'll eat aquatic plants. They are not very picky; they'll eat almost anything that fits
into their mouth. Aquatic salamanders eat insects, small fish, and tadpoles. When
they are young, salamander larvae will eat each other or daphnia, insect larvae,
snails, and tadpoles.
Terrestrial salamanders and aquatic
salamanders have different hunting
habits. An aquatic salamander lurks
around in the water until something of
its liking comes along. Its mouth then
snaps open so quickly that the prey
and water surrounding it goes rushing
into the salamander's mouth. When it
closes its mouth it swallows the treat.
A terrestrial salamander obviously does things differently because it lives on land.
Sometimes it just waits for its prey to come along. Most of the time, it actively hunts
for its prey. All salamanders have teeth made out of the same things that human
teeth are made out of. Salamander teeth are too small and too fine for chewing food,
however. They are only used for catching and holding prey. Some salamander
predators are herons and other birds, snakes, foxes, shrews, voles, and frogs. Fish
eat salamander eggs and larvae.
Caecilian
N o t a s n a k e
a n d n o t a
w o r m — i t i s a
l e g l e s s
a m p h i b i a n .
C a e c i l i a n s
m o v e a r o u n d
i n a f a s h i o n
s i m i l a r t o
y o u r t o n g u e .
A c a e c i l i a n ' s b o d y
c a v i t y a c t s a s a

5. p r e s s u r i z e d c o n t a i n e r .
M u s c l e s s u r r o u n d i n g
t h e c a v i t y s q u e e z e o n
t h e l i q u i d . T h i s
i n c r e a s e i n p r e s s u r e
c a u s e s t h e c a e c i l i a n
t o e l o n g a t e , t h a t i s ,
t o g e t l o n g e r . U s i n g
t h i s m e t h o d ,
c a e c i l i a n s c a n
p r o d u c e a b o u t t w i c e
t h e f o r w a r d f o r c e a s a
s i m i l a r s i z e d
b u r r o w i n g s n a k e .

6. Defense
Compared to other vertebrates, which may be faster and stronger or possess
poisonous bites or sharp claws, amphibians are relatively easy prey. In water and on
land, they are pursued by a hungry throng of birds, mammals, reptiles, fishes, and
other amphibians. Yet they have managed to survive for millions of years.
Amphibian Armor
Amphibians don’t have fangs and talons, but their subtle defense systems still
function well. They have relatively small, slippery bodies and a generally quiet and
retiring nature. Many species don’t show themselves in daylight. Amphibians also
have other survival tricks, many involving coloration.
Flashing
Flash coloration is different from warning
coloration because it is not seen until the
amphibian is under attack. The bright colors
distract and confuse predators and help the
amphibians escape.
Rough-skinned Newt flashing
its colors. © E. R. Degginger -
Color-Pic, Inc.
Poisons
Many amphibians produce mild skin
poisons, and some secretions are toxic
enough to kill predators. In salamanders,
the tail is often the most poisonous part
(and the part predators can most easily
grab).
The Colorado River Toad has poison
glands behind the eyes. © Dennis
Sheridan

7. Other Tricks
Imitating poisonous species can help keep salamanders alive. Some use the old
trick of playing dead. Others protect themselves by biting. Sirens even scream and
yelp. One unusual defense is the ability to survive, at least for a while, in the
stomach of a predator. Poisonous Red Efts can live there up to 30 minutes, by which
time they have usually been spit up by whatever swallowed them.
The bright color of the Red Salamander warns predators to stay away. © R. D.
Bartlett
Color-change Artists
The Gray Treefrog changes color
to match the environment. © Bill
Beatty
Changing skin coloration is employed by frogs,
toads, and some salamanders. Treefrogs and
other color-change artists change their colors
over time to match the background they rest
upon.
Standing Out
If eaten, the poisonous Red Eft
(immature Eastern Newt) will make
predators sick. © Byron Jorjorian
Warning coloration is the opposite of protective
coloration. Bright colors on the upper surface of
the skin usually mean the amphibian has quite
poisonous skin. Predators who attack a brightly
colored amphibian quickly learn to avoid similar-
looking ones in the future.

8. Blending In
Protective coloration is important to many
amphibians, a large number of which are green,
brown, or gray—colors that are common in
nature. These color patterns act as camouflage,
helping amphibians blend in with their
surroundings.
Canyon Treefrog blends into
granite. © C. Allan Morgan
Diet
All adult amphibians are meat eaters, or carnivores. They actively search for other
animals—usually insects—to eat. Larval salamanders are also meat eaters. Most
larval frogs are plant eaters, or vegetarians, although a few eat both plants and small
animals.
Is a Newt a Salamander?
Yes, but a
salamander is not
always a newt.
Confused? The word
"salamander" is the
name for an entire
group, or scientific
order, of amphibians
that have tails as
adults. This includes animals commonly known as newts and sirens. Most of the
animals in the salamander order look like a cross between a lizard and a frog. They
have moist, smooth skin like frogs, and long tails like lizards. The term "newt" is
sometimes used for salamanders that spend most of each year living on land. The
name "siren" is generally given to salamanders that have lungs as well as gills and
never develop beyond the larval stage. Other names salamanders go by include
olm, axolotl, spring lizard, water dog, mud puppy, hellbender, triton, and congo eel.
Whew!
From Head to Toes
Most salamanders are small, and few species are more than 6 inches (15
centimeters) long. Their heads are narrow and they have small eyes. Sirens have
only two legs, but the other salamander species develop four legs as adults, with
fleshy toes at the end of each foot. Some species, like paddle-tail newts Pachytriton
labiatus and male palmate newts Triturus helveticus, have fully webbed feet with
very short toes to help them climb on slippery surfaces. Those that like to dig, such

9. as the tiger salamander Ambystoma tigrinum, have no webbing at all on their feet. A
salamander’s hind legs grow more slowly than its front legs. (Frogs and toads are
just the opposite. Their hind legs grow more quickly than their front legs.) All four
legs on a salamander are so short that its belly drags on the ground. The exception
to this is the sirens. They don’t have hind legs at all! Their long, strong tails are flat to
help sirens swim like a fish, with the tail flapping from side to side.
Take a Deep Breath
Different members of the
salamander order have developed
different ways of breathing. Sirens
keep their gills all their lives,
allowing them to breathe
underwater. Others, such as the
tiger salamander, lose their gills as
they grow older and develop lungs
to breathe air. But most, like the
arboreal salamander Aneides lugubris and the California slender salamander
Batrachoseps attenuatus, don’t have lungs or gills as adults. Commonly called
lungless salamanders, they breathe through their skin and the thin membranes in
the mouth and throat.
All Wet!
Newts usually have smooth, slick skin and salamanders have dry, warty skin. But of
course there are exceptions! A fire salamander’s Salamandra salamandra skin is
smooth and damp, while crested newts Triturus cristatus shed their dry, warty skin
when they return to the water to breed. But no matter what it may look or feel like,
salamanders and newts need to keep their skin moist. If they get too hot and dry,
they could die.
Land or Water or Both?
Since salamanders need to stay cool and moist to survive, those that live on land
are found in shady forested areas. They spend most of their time staying out of the
sun under rocks and logs, up in trees, or in burrows they’ve dug in the damp earth.
Some will seek out a pool of water where they can breed and lay their eggs, before
returning to the land. Others, like sirens, olms Proteus anguineus, and axolotls
Ambystoma mexicanum, spend their entire lives in the water.
Life Cycle
Different salamander species have different life cycles, too. Some breed, lay their
eggs, and hatch on land. Others, such as some newts, breed and lay eggs in the
water. When the eggs hatch, the larvae grow up in the water, then return to the land

10. as adults. Still others, such as the giant salamander Andrias sp. and the hellbender
Cryptobranchus alleganiensis, spend all the stages of their life cycle in water.
Lungless salamanders have eggs that hatch directly into small salamanders,
skipping the larval stage entirely!
Bringing Up Baby
Most salamander species hatch from eggs. Female salamanders that live entirely in
the water lay more eggs—up to 450—than those that spend some time on land. The
California newt Taricha torosa lays a clump of 7 to 30 eggs on underwater plants or
exposed roots. The eggs are protected by a toxic gel-like membrane. Lungless
salamanders such as the spiny salamander Plethodon sp. are devoted parents that
share egg-guarding duties. They curl their bodies around the eggs and turn them
over from time to time. This protects the eggs from predators and from fungal
infections. Some mother newts keep their eggs safe by wrapping leaves around
each one as they are laid—up to 400 eggs! Salamanders in the larval stage of their
development are called efts.
What’s on the Menu?
All salamanders are carnivores, but they are seldom in a hurry to catch their meals.
Because they move more slowly than other meat eaters, salamanders tend to eat
slow-moving, soft-bodied creatures such as earthworms, slugs, and snails. Larger
species may eat fish, crayfish, and small mammals such as mice and shrews. They
might approach their target slowly, then make a quick grab with their sharp teeth. Or
they might hide and wait for a tasty meal to pass close enough to snatch. Several
species can flick out their tongues to catch their food as it goes by.
Staying Safe
Would you want to eat something that tasted awful or hurt your mouth? Probably
not! Salamanders have some special ways to keep from becoming another animal’s
next meal. Most salamanders, such as the red-spotted newt Notophthalmus
viridescens, have brightly colored, poisonous skin. The bold color tells predators that
the newt is not safe to eat. Many salamanders have glands on the back of the neck
or on the tail. These glands can secrete a poisonous or bad-tasting liquid. Some
species can even shed their tail during an attack and grow a new one later. The
ribbed newt Pleurodeles waltl has needlelike rib tips. It can squeeze its muscles to
make the rib tips pierce through its skin and into its enemy, teaching it a sharp
lesson! The California salamander Ensatina eschscholtzii stands high on its legs and
waves its tail to scare away danger.

11. Humans: The Biggest Enemy
Unfortunately, people are the salamanders’ worst enemy. Humans continue to
pollute and destroy wetland habitats. Remember, these amphibians need water to
survive. Filling in their ponds, using pesticides, and rerouting water for our own water
needs has caused declines in many salamander populations. We need to help
conserve remaining habitats and provide new gardens and parks for these unique
creatures.
 The fire salamander is the only amphibian that does not hatch from an egg.
Instead, the babies develop inside the mother’s body.
 Only two salamander species have small, pointed claws on their toes: the
long-tailed clawed salamander Onychodactylus fischeri and the Japanese
clawed salamander Onychodactylus japonicus.
 The only cave-dwelling amphibian is a salamander called an olm. Olms have
very pale skin and have adapted to living in complete darkness in
underground pools of water.
 The slow lifestyle of salamanders may help them live long lives. Smaller
species may live 25 years or so, with some living up to 55 years.
 Salamanders can’t hear sounds, so they don’t make any either. However,
some species can hug the ground to pick up sound vibrations with their
bodies.
Class: Amphibia (Amphibians)
Order: Caudata
Family: 9 families
Genus: 60 genera
Species: 358 species
Size: largest—Japanese giant salamander
Andrias japonicus, head-to-tail length 6

12. feet (1.8 meters); smallest—Thorius arboreus, head-to-tail length 0.6 inches (1.7
centimeters); most salamanders are 2 to 6 inches (5 to 15 centimeters)
Weight: largest—giant salamanders, up to 140 pounds (63 kilograms)
Life span: up to 55 years, depending on species
Number of young produced: from 1 to 450 eggs are laid, depending on species;
fire salamander Salamandra salamandra is a live-bearing species, giving birth to 10
to 30 young
Conservation status: Lake Lerma salamander Ambystoma lermaense and
Sardinian brook salamander Euproctus platycephalus are at critical risk; many
others are endangered.
Tadpole Carnivores
All tadpoles have special scraping
mouthparts that are used for feeding on
algae. Tadpoles of a few species, especially
the spadefoot toads, sometimes become
cannibals. They often eat their fellow
tadpoles and can grow to enormous size,
much larger than their vegetarian brothers
and sisters.
Tailed Frog tadpole. © R. D. Bartlett
Young Bullfrog eating an
earthworm. © Kenneth H. Thomas -
Photo Researchers, Inc.
As Long As It’s Wiggling...
Amphibians generally are not very particular
about what they eat. Just about anything that is
alive and fits in their mouth is fair game for
adult salamanders and frogs. Some
invertebrates (creatures without backbones),
such as spiders, snails, worms, insects, and
crayfish, are common in amphibian habitats
and are eaten regularly. Narrowmouth toads
are one of the few amphibians that eat mostly
one thing. They specialize in eating ants.

13. Cannibals
Amphibians will eat many types of
creatures. Fishes, reptiles, snails, baby
birds—even other amphibians—are
gobbled down if the opportunity arises.
Tiger Salamander eating another
salamander. © Joe McDonald
Caecilians are amphibians that resemble large earthworms in shape, but are a
different colour (yellow or even purple) and of course possess a bony internal
skeleton. There are no external ears, and the eyes are usually reduced or covered
by bone or the outer skin. Their mouths, however, are large, and they are
predacious upon various small fish or invertebrates. They tend to burrow in both the
wild and in captivity.
Quite simply put, caecilians are relatively unknown. The ordinary layman who knows
frogs or newts will never have heard of caecilians, and even herpetologists are
probably by and large ignorant of these unusual creatures. I have never seen one in
this country, either in the pet trade or zoos. Most books on herpetology give them a
passing mention, if at all. Coupled with the dearth of knowledge is the obvious fact
that, as burrowing creatures, they are hardly likely to be seen much by any
prospective keeper.
Yet here is perhaps one of the greatest challenges to herpetologists, amateurs
included (and I'm an amateur). A lot could still be learnt about these creatures and
their requirements simply by keeping one aquarium containing one or more. As even
the basics seem very basic where knowledge of caecilian-keeping is concerned, real
pioneering work could be made by a few dedicated people.
Caecilians roughly fall into two camps, the terrestrial and the aquatic, though both
obviously need moisture. The aquatic are apparently more often seen since some
get shipped, probably accidentally, with consignments of tropical fish. Both types
need tropical temperatures, about 25 C. For food, Eric M Rundquist recommends
earthworms (with a caution about the possibility of parasites), or alternatively lean
raw beef strips, beef heart strips, gray crickets and pinkies or fuzzies for terrestial
caecilians, and brine shrimp and chopped earthworms, with intermittent crickets,
guppies and minnows for aquatics.
It is true that little interaction may be expected from a caecilian. However, if you treat
your captive as a dignified object of research, rather than looking for an owner-pet
relationship, you may find it rewarding.