UNIT

2The nutrition function

Natural Science 2. Secondary Education

HOW SOME ANIMALS TAKE OXYGEN

FROM THE WATER

UNIT

2

RESPIRATIONIN WATER

THROUGH THE BODY SURFACE

THROUGHGILLS

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How some animals take oxygen from the water

is carried out

Natural Science 2. Secondary Education

UNIT

2• This is seen in animals that live underwater or in very wet environments, like the soil.

• Sponges, cnidarians (polyps and jellyfish), worms and some amphibians absorb air in this way.

Respiration through the body surface

The animal absorb O2 through its surface

The animal eliminates CO2 through its surface

O2 O2CO2 CO2

Respiration through the body surface in an annelid.

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Wetenvironment

Bodysurface

How some animals take oxygen from the water

Natural Science 2. Secondary Education

UNIT

2• Gills are very thin sheets or filaments full of capillaries.

• When water passes through the gills, carbon dioxide from the circulating liquid inside the organism is exchanged for oxygen from the water.

• Gills are the respiratory organs of aquatic molluscs, crustaceans, fish and some amphibians.

Respiration through gills

Blood with O2 Blood with CO2

Water

Water with O2

Water with CO2 Respiration through

gills in a fish.

O2

CO2

How some animals take oxygen from the water

Go back to the Start menuNatural Science 2. Secondary Education