Frogs are found throughout the world, inhabiting a vast range of habitats. Glob-ally, there are over 7,000 species of frogs (which includes the toads). They are found on every continent, except Antarc-tica, which is too cold for them, and in almost every habitat type. Typically, frogs are associated with warmer, moist environments and species density is con-centrated in the equatorial regions.

There are 135 species of frogs in South Africa (as of 2018), which are unevenly distributed across the country, both in terms of species and density. The three main determinants of distribution patterns are climate, centre of origin and range restriction.

Frogs in the Classroom

Frog habitats Lesson 2

Fun Froggy Fact

New frog species are discovered every

year. On average, 147 new species have

been described every year for the past

10 years. Fourteen of these are from

South Africa

The rich amphibian fauna of southern Africa is attributed to the diversity of the region’s topography, climate and habitats. Frogs have adapted to almost every type of en-vironment on the subcontinent and many species are highly specialised to suit conditions in a particular locali-ty, including even in desert environments. In spite of some remarkable adaptations to cope with changing en-vironmental conditions, all amphibians remain physio-logically dependent on moisture and temperature. Thus a larger number of species are found in areas that are warm and wet. The number of species found at any lo-cality increases from the arid west to the water east of the subcontinent.

Most southern African frog species fall into two broad categories. The first comprises species with evolutionary origins centred in the southern provinces or high altitude areas of the interior. The second comprises species with tropical origins distributed in the north-east. During past periods of climatic warming the distribution of tropical species expanded southwards, while those already inhabiting the south retreated. During periods of cli-mate cooling this process was reversed. At the interface between theses two faunal groups, some populations became isolated and evolved into independent allopatric species. There is an increase diversity northwards along the coast from the Western Cape towards northern Kwa-Zulu Natal, and an increase in endemicity southwards. In general, the interior of the region has a lower level of species diversity and en-demicity.

Frogs in the Classroom

Frog habitats Lesson 2

The environmental conditions need to be suitable

for frogs and most species are located only in

very specific habitats.

In South Africa, there are nine biomes and within

each biome frogs can be found: Coastal bush, for-

est, desert, grassland, karoo, fynbos, mangroves,

moist and arid savanna.

In general, forests and flowing freshwater biomes

are where the most diversity of frogs are found.

While arid and semi-arid habitats are where frog

species are less diverse.

Several southern African species have restricted ranges of less than 20 000km², confined to 13 isolated topographical areas. This means that, for example, mountains and deeply incised river valleys, are barriers which have limited the movement of these species.

Frogs in the Classroom

Frog habitats Lesson 2

Areas covered by water are known as wetlands. Marshes, ponds, pans, vleis and estuaries are

all types of wetlands. Globally, wetlands provide ideal habitats for frogs.

Wetlands provide:

A home for plants and animals;

Water storage and filtration;

Protection against floods;

Food and resources; and

Areas of recreation and An income for surrounding communities.

Many people rely on wetlands for food and re-

sources. Our wetlands are being drained for

mining, agriculture, and development. Losing

wetlands threatens biodiversity and livelihoods and means we lose a clean water supply and a

natural water storage system.

Subject: Natural Sciences

Specific Aims

1. Doing science

2. Knowing the subject content and making connec-tions’

Process Skills

Accessing and recalling information; observing, raising questions, doing investigations, recording and inter-preting investigations.

Integration

Language and Life Skills

Lesson Format

Work though the information in the factsheet with learners and complete worksheet 2.1., practical 2.1. and visit a wetland using field visit sheet 2.4.

Assessment

1. Worksheet 2.1. Frogs in South Africa

2. Practical 2.1. Wetland in a bottle

3. Field visit 2.3. Wetland visit

Next Lesson

Frog Identification

Frogs in the Classroom

Frog habitats Lesson 2

Fun Froggy Fact

The Bush Squeaker lays its eggs in the leaf litter on the forest floor. There is no free-swimming tadpole phase, rather, the entire development is completed within an egg capsule and tiny, fully metamorphosed frogs emerge after about four weeks.

A forest is characterized by dense woodland of large trees which form a closed canopy. For-ests occur in patches in high rainfall areas along the south and eastern escarpments at various altitudes in South Africa. These environmental conditions make it a suitable habitat for frogs to live.

Forests provide:

Climate control;

Air purification;

Soil stabilization;

Food and natural resources; and

Support a high biodiversity.

People depend on forests not only for the services they provide but also generate an income through forests. However, forests are under threat from deforestation which threatens the not only frog survival but biological diversity and human wellbeing.

An example of a frog that lives in a forest the Bush Squeaker, Arthroleptis wahlbergi

Worksheet 2.1.

Frogs in South Africa

Name: _______________________________ Surname: ____________________________

Grade: ____________________________ __ Date: ________________________________

Task: Complete the following questions using the species richness map

1. How many species of frogs are there globally (1)?

2. How many species of frogs are found in South Africa (1)?

3. Whereabouts is the highest number of frogs in South Africa found? (3)

4. Why do you think there is such a high number of frog species found in these areas? (3)

5. What is the average number of spe-

cies frog found in Kwa-Zulu Natal? Is

it high or low? And why is this? (3)

6. What is the average number of frog

species found in the Northern Cape?

Is it high or low, why? (3)

____/15

Worksheet 2.1.

How forests help to clean air

Name: _______________________________ Surname: ____________________________

Grade: _______________________________ Date: ________________________________

Task: Conduct the photosynthetic efficiency test to observe how trees absorb carbon dioxide and

release oxygen

You will need:

Container;

Water;

Dishwashing liquid;

Bicarbonate of soda;

Syringe

Light;

A punch; and

Leaves.

Directions

Obtain 300 mL of bicarbonate solution. (It contains 1/8 tsp of sodium bicarbonate)

Add 1 drop of soap to the bicarbonate solution. If your solution generates excessive suds, add more water and bicarbonate.

Hole punch 10 uniform leaf disks in texture and thickness avoiding major leaf veins .

Remove the plunger of the syringe and place 10 leaf disks in the syringe barrel .

Replace the plunger being careful not to crush the leaf disks.

Push on the plunger until only a small volume of air and leaf disk remain in the barrel

Draw a small volume of the sodium bicarbonate solution into the syringe.

Invert the syringe and tap the syringe to suspend the leaf disks in the solution.

Push the plunger removing as much air a possible from the syringe.

Hold a finger over the syringe opening and draw back on the plunger to create a vacuum. Hold this for 10 seconds while swirling the syringe to further suspend the leaf disks in solution.

Let off the vacuum and repeat step 8 if needed 2-3 more times until all leaf disks sink. If leaf disks do not sink, add more soap to the bicarbonate solution.

Pour the disks and solution into the cup with bicarbonate solution

Place the cup under a light source;

Observe what happens. The leaf discs will begin to rise. This shows that the leaves are photosynthe-sizing taking in the carbon (bicarbonate of soda) and releasing oxygen which makes the leaf discs rise to the top.

Why is this important to the survival of frogs?

Practical 2.1.

Make a wetland in a bottle

Name: _______________________________ Surname: ____________________________

Grade: _______________________________ Date: ________________________________

Task: Follow the directions below to make your own wetland in a bottle.

You will need:

An empty 2 litre bottle cut in half along the length;

Coarse sand,

Fine sand,

A few small rocks,

A few grass clippings; and

The lid of the bottle.

Directions

Step 1

1. Cut the 2 litre bottle in half along the length without damaging the neck of the bottle.

2. Plug the neck of the bottle with grass clippings.

3. Fill bottom of the bottle with the coarse sand.

4. Put a layer of fine sand on top of the coarse sand.

5. Pack the stones in a little heap near to the fat end of the bottle.

6. Now put the fat end of the bottle on top of the lid of the bottle and rest the neck of the bottle in a little bowl in such a way that the bottle is at an angle going down towards the neck. The bottle has to be at an angle so that the water will run down from the fat end towards the neck of the bottle and into the bowl.

Step 2

Slowly pour water over the rocks. Watch through the sides of the bottle to see what happens. See how the water level in the sand rises. This can be compared to groundwater in a real wetland.

Step 3

Now mix water in a see-through container with dirt until the water is murky and muddy. Slowly pour the murky water over the stones in the "wetland". Keep a little bit behind in the container. Wait until the water has moved through the soil and flowed into the little bowl underneath the neck of the bottle. What is the colour of the water? Compare it to the colour of the murky, muddy water left behind in the see-through container.

Field Trip 2.1.

Visit a frog habitat Name: ________________________________ Surname: _____________________________

Grade: _____________________________ __ Date: ________________________________

Task: Visit a habitat in your area and conduct a habitat study:

Describe the habitat and draw a diagram of the wetland. (10)

List 5 plants that you observed at the habitat. (5)

List 5 animals you observed at the habitat. (5)

Did you find any frogs? (1)

What kind of frog was it? (1)

How big was the frog? (1)

Where did you find the frog? (1)

What was it doing? (1)

Describe any threats to frogs that you can observe in and around the habitat. (4)

_______/29

Assessment Sheet 2

Learner Name and Surname Worksheet 1 Practical 2 Field visit Total Average

Frogs in the Classroom

Frog habitats Lesson 2

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frogmap.adu.org.za/Coverage_species_richness_maps.php

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vegetation/savanna.htm

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redlist.sanbi.org.za

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namakaroo.htm

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vegetation/succkaroo.htm

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thicket.htm

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