Grade Six Science Fish

Let’s look carefully at the parts of a fish below.

Hello Boys and Girls,

Are you revising quite a lot? Are you having lots of fun at school? Are you working as hard as you can? Are you paying full attention in class? Did you do last week’s exercise well? Have you been observing different birds? Wasn’t that an exciting activity to do!

Let’s look at the pictures of the birds below. Can you tell what type of food each bird eats?

Draw the beaks of these birds. Did you do a good job with that?

I hope you remembered the type of food each bird eats. If not, check last week’s article.

This week we will look at another type of animal. We will look at fish. The first exercise for you to do is to name as many fish found in Guyana as you can. Compare your list with that of a friend. Encourage others to do the same. Ask your teacher to have the lists displayed in your class. You can even have a competition. Do this quickly, as soon as possible.

Do you like to eat fish? Fish is very nutritious and good for you. Do you know to which food group the fish belongs? If you don’t know, find out. What nutrients do you get from fish?

Fish come in an amazing variety of colours, shapes and sizes. There are more than 25,000 known species of fish, and some have not been discovered as yet. That’s a lot of fish! If you see a big lot of fish together, what would you call that?

Most fish are cold-blooded, unlike us who are warm-blooded. Do remember that being cold-blooded means that they do not maintain a constant body temperature inside; instead their temperature is greatly influenced by their environment. There are exceptions to fish being cold-blooded, though: the Tuna and the Mackerel sharks have warm blood like us. Have you ever heard of an Opah fish? That fish also has warm blood.

Fish are vertebrates. They have a spine and bones. Do you know of any exceptions?

Fish are aquatic. They live in water. They can be found in the sea, rivers, lakes, streams and ponds.

Fish vary in size. Some are huge. The biggest fish on the planet is the whale shark. It can grow up to 12 metres long and can be as heavy as 18.7 tonnes! That’s as heavy as a big truck!

There are three classes of fish. They are: i. The jawless fish, which doesn’t have a true jaw but a sucker- like mouth and rasping teeth.

ii.

The cartilaginous fish, whose skeletons are made of cartilage, which is not as hard as bone

iii. The bony fish, which have skeletons made of bone. They are the most numerous group.

What are fish covered with? Yes, most fishes are covered with scales. Scales are little slightly round plates. They overlap each other. The scales provide protection and they always point backwards towards the tail.

The body of a fish is divided into head, trunk and tail. There is no neck. On the head a pair of nostrils is present. You can also find a pair of eyes. It has a spindle shaped body which is helpful in swimming.

Can you see the lateral line on the side of the body? Check the diagram again. Sense organs are present in the lateral line. They detect the pressure changes of water.

The body shows paired fins and unpaired fins. Can you identify the paired fins and the unpaired fins? The pectoral and pelvic fins are paired. They are in twos. The dorsal and ventral fins are not paired fins. Take another look at the caudal fin. What is another name for caudal fin?

What do the fins do? They help the fish to maintain its balance in the water. They also help in moving – turning, steering, pushing off, . .

Fish swim by flexing their bodies, forming waves of contractions along their muscles. These waves push the water backward and move the fish forward.

Most fish have scales covered with a slimy substance that helps to protect them. The scales may be roundish, thin and flat. Some scales have tiny teeth on their edges, and some scales are thick and shaped like a rhombus.

Ensure that you know to draw and label the fish.

Label the following fish

Look at this diagram.

External Parts of a Fish

Can you see the gills of the fish? Why do fish have gills? That’s right. They breathe through their gills. Most fish breathe through their gills. Gills are the extensions of the pharynx. In bony fish, the gill slits are covered by the operculum.

For your homework:

Do you know the functions of the fins? Write the functions in the lines provided below.

Dorsal fin: _______________________________________________

Ventral fin: _______________________________________________

Caudal fin: _______________________________________________

Anal fin: _________________________________________________

Pectoral fins: ______________________________________________

Adipose fin: ______________________________________________

Until next week, Boys and Girls, goodbye!