Download Chapter 31: Fishes and Amphibians

Chapter 31: Fishes and Amphibians
Section 2: Amphibians
Amphibians

About __________________ living species

______________________________________ are the smallest major group of
vertebrates

Range in size from tiny tropical tree frogs 1cm long to enormous salamanders 170
cm long

Some have __________________________ and walk on
____________________________

Others have _________________________ and leap from one place to another
with large ____________________________

They are descendents of ancestral organisms that evolved some of the adaptations
necessary for _________________________________

Nearly all of them are restricted to __________________________________, and
most of them must return to ___________________________________________
What Is an Amphibian?

The name amphibians refers to the __________________________________ that
most amphibians lead
o __________________________ are fishlike aquatic animals that breathe
through gills
o _____________________ are terrestrial carnivores that breathe through
lungs and skin

Amphibians are strongly tied to the water because their eggs do not
______________________________________

Their skin does not have scales or any other protective covering

The skin of almost all adults is used in ______________________________ and
must remain __________________

Amphibians can be defined as vertebrates that are aquatic as larvae and
terrestrial as adults, breathe with lungs as adults, have a moist skin that
contains many glands, and lack scales and claws
Evolution of Amphibians

Amphibians first appeared about ____________________ million years ago

Amphibians evolved from ____________________________________________

Making the transition from water to land was not easy

Because natural selection favored individuals that were better able to live on land,
early amphibians evolved in ways that went above many problems
o ___________________ became stronger
o Ribs formed a cage to protect ___________________________________
o _______________ were added to the lateral line system
o Mucous glands, eyelids, and other structures that protect
_______________________________________ from drying out
developed

When amphibians started crawling onto land, they entered an environment nearly
________________________________________________

Any vertebrates whose legs and lungs allowed them to spend time on land had
lots of food and no competitors

This was ______________________________

________________________________________ ultimately caused many of the
low, swampy amphibian habitats to disappear

Most of the amphibian groups became extinct about ___________ million years
ago
Form and Function in Amphibians

Living amphibians have evolved many adaptations that help them overcome the
problems of living both in water and on land

As we examine the essential life functions in amphibians, we will focus on
__________________
Feeding

Tadpoles are typically _________________________________ or
___________________________

Tadpoles have to grow _____________________________
o Those that lag behind may starve or die if their puddle dries out

Adult amphibians are almost entirely _______________________________

From the mouth, food slides down the esophagus into the ___________________

The stomach connects with the ____________________________________

The small intestine leads to the large intestine, or ______________________

At the end of the large intestine is a muscular cavity called the
________________________, which stores wastes until they are expelled
Respiration

Adults typically breathe using ___________________, mouth cavities, and
_________________

The lungs are reasonably well developed
o _______________________________

The lining of the mouth cavity and the body skin are thin and richly supplied with
blood vessels

Most ________________________________ is removed through the
__________________

Frogs cannot inhale and exhale as we do
o They fill their mouth cavity with air, close their mouth, and force air back
through an opening called the ____________________ into the lungs

Frogs can also direct some of the air they take in to a pair of _________________
_______________
Internal Transport

Circulatory system is a _____________________________
o First loop carries oxygen-poor blood from the heart to the lungs and takes
oxygen-rich blood from the lungs back to the heart
o The second loop transports oxygen-rich blood from the heart to the rest of
the body and oxygen-poor blood from the body back to the heart

______________________________________
o Left atrium, right atrium, and ventricle

Tadpoles have _____________ chambered hearts and
_________________________________ circulatory systems
Excretion

Amphibians use _____________________ to eliminate wastes from their
bloodstream

The kidneys are dark colored oval structures that lie against the dorsal part of the
body wall

The excretory product of the kidneys – __________________ – travels through
tubes called ______________________ into the ___________________

From there it can be passed directly to the outside or it may be stored in a small
urinary bladder
Response

Well developed nervous and sensory systems

Large eyes with a ______________________________________________
o Protects from damage under water
o Kept moist on land
o Located inside the regular eyelid

Ears have no _________________________ sound collectors
o Hearing is vital to their survival and reproduction

Respond to adverse conditions in many different ways
o Being in a sheltered spot, _____________________________
o _____________________________
o __________________________ or _______________________________
__________________________
o ________________________________________
Reproduction

When frogs reproduce, the male climbs onto the female’s back and
____________________________

In response to this, the female releases as many as ________________________

The embryos are surrounded with a sticky substance that attaches the egg mass to
underwater plants and nourishes the developing embryos

The eggs typically hatch into tadpoles after ___________________________

Not all amphibians have external fertilization

Parental care in amphibians varies greatly

Some frogs incubate their young in their __________________,
_____________________________, or __________________________

Some have special sacs to store the eggs

In certain tree frogs, tadpoles cling to their parent’s back with a sucker like mouth
and are carried between pools of rainwater that collect among the leaves of certain
plants
Salamanders

These amphibians keep their _____________________ even as adults

Both adults and larvae are _____________________________

Most modern salamanders are about ___________________

Most hatch as fully aquatic larvae with gills

As adults they live in moist woods, where they tunnel under rocks and rotting logs

Some salamanders never lose their gills and live in water all their life

Some newts switch back and forth between water and land
Frogs and Toads

Of the two, _________________ are most closely tied to water

Frogs spend much of their time in or near ponds and streams

Adult ______________, on the other hand, often live in moist woods

These animals burrow deep into moist soil and press their skin against the walls of
their burrows

Many toads and frogs produce potent ____________________

One species of poison arrow frog produces a toxin so powerful that
_____________________________ can kill an adult human
How Amphibians Fit into the World

Prey on _____________________

___________________________ are a delicacy in some cultures

Native hunters tip their arrows with toxins to kill large animals

Researchers are studying the action of poison arrow frog toxins for clues to the
way the ________________________________________

Studies of ______________________________