Grade 4
Lesson 3
Water animals - Sea life
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Sea or land?

More creatures live in the sea than on land. Some animals live only in the sea. Others live both in the sea and on land, while others live from the sea. Such animals need the salty waters of the sea.

Which animals live in the sea?

Many different animals live in the sea.We can split up these animals into two groups: vertebrates and invertebrates.

Vertebrates are animals that have a spine, and invertebrates are those that do not have a spine.

Invertebrates often have a shell or an exoskeleton for protection.

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Fins

There are many fish in the sea, great and small. They do not have arms or legs. There are many kinds of fish, with many shapes and colors. They also eat many different things.

You have different types of fin too:

Dorsal fin

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2 pectoral fin

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1 anal fin

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Where do they use their tails for?

Fish use their tails and two pectoral fins to gain speed and the other fins to steer. To float, they use a swim bladder.

Fish do not have lungs, but they use their gills to breathe.