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

oRibs formed a cage to protect ______

o______were added to the lateral line system

oMucous 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 ______

oThose 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

oThey 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 ______

oFirst loop carries oxygen-poor blood from the heart to the lungs and takes oxygen-rich blood from the lungs back to the heart

oThe 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

______

oLeft 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 ______

oProtects from damage under water

oKept moist on land

oLocated inside the regular eyelid

Ears have no ______sound collectors

oHearing is vital to their survival and reproduction

Respond to adverse conditions in many different ways

oBeing 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 ______