Fish Swim
Why do fish swim so fast?
  • Fish have muscles that pull on its skeleton to flick its tail and push it forward through the water. The stronger the flick of the tail, the faster the fish can swim.
  • Fish have streamlined bodies and they make a special slime that coats their bodies so they slip through the water easily.
  • Fins give a fish control over its movement by working a bit like a steering wheel and brakes.
  • Fish also have a swim bladder for swimming at difference depths. The swim bladder is like a tiny balloon inside the fish. Fish use their swim bladders to keep themselves afloat. By changing the amount of air in their swim bladders, fish stay balanced in the water. When a fish wants to swim deeper it lets out air from itís swim bladder and when it wants to go up higher in the water, it takes more air into its swim bladder.
  Did You Know?
  • There are some sharks and fish like Tuna that can reach speeds of over 80 kilometres an hour.
  • There are over 25,000 different species of fish in the oceans, lakes and rivers of the world.
  • Most fish can only swim forward but there are a couple of different types of fish that can swim backwards too.
  • Most fish cruise around in the water moving all the time at a pretty constant speed but some stay in one place then move in short bursts of speed.
  • Fish need to be able to swim fast to escape from bigger fish that want to eat them!
Discover how a swim bladder allows a fish to move up and down in the water.

What you need:
A big clear container that will hold about 1 litre of water
Tap water
2 glass marbles
2 balloons

What you do:
Fill the container three quarters full with water. Place a marble inside each balloon. In one of the balloons tie a knot as close to the marble as possible. Drop the balloon in the jar of water. Slightly inflate the second balloon with air by blowing air into it then tie a knot as close to the mouth of the balloon as possible. Drop this balloon in the jar of water.
What are your results?
This is how a fishís swim bladder works. With less air a fish will sink to the bottom and with more air it will rise to the top.
Next time youíre having Flounder for tea think about how they would move through the water. Flounder are the ones that live on the bottom of the sea.
Find out which fish can swim backwards as well as forwards - there arenít many of them, but there are some.
What part of a fish weighs the most?
The scales

How do you talk to a fish?
Drop it a line
From k.s.Edwards?

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