Make your own Gray Whale!
Description
Whales are able to dive deep under the ocean waters. With a few simple materials, you can make a simulation of underwater diving that will give you some idea of how sea animals are able to dive and stay down there.
Materials
Empty
plastic 2 liter soft drink bottle with a cap and an
eyedropper to use for your "whale."
What to Do
Fill
the empty plastic bottle with tap water. The eyedropper
will need to be filled with a certain amount of water to
make it sink. This can be a tricky part. Depending on how
big your eyedropper is, you can squeeze the dropper and
fill it about a third of the way with water. Don't put
too much water in the dropper or your "whale"
will sink and never come up again. After putting the
right amount of water in the dropper, put the dropper
gently in the water-filled bottle and screw the cap on
tight.
Now
you are ready to try a dive. Place both hands on the
sides of the bottle and squeeze the bottle gently.
If
you have placed just enough water in the eyedropper, your
"whale" will slowly dive down to the bottom of
the bottle. Fun! If the eyedropper doesn't dive no matter
how you much you squeeze, try fishing the eyedropper out
of the bottle and adding a bit more water. But remember,
if you add too much water the dropper will sink and it's
hard to get it out again without emptying the whole
bottle. Believe me, it's true.
Once you get a working diver, you can easily make it dive
and surface by just squeezing the bottle a little bit. If
you get good at it, you can make the "whale"
dive to the middle of the bottle and stay there for a
while.
Questions
- Look closely at the dropper as
you squeeze the bottle. Is there any change in
the water in the dropper?
- Look closely again at the
dropper as you squeeze the bottle. Is there any
change in the AIR in the dropper?
- What is making the dropper sink as you squeeze the bottle?
Think about it
It's a good thing that whales and other sea animals can dive under the water so they can get food and get away from dangerous creatures. But if whales are full of air they will float on the surface of the water like a balloon. Many sea creatures take in an amount of water so they will be heavier and sink down under the ocean. They can change their ability to float or sink whenever they want to.
Whether an animal sinks or floats is called "buoyancy." If you have ever been to an aquarium and seen a sea animal hovering in one spot under the water, chances are that the animal was "neutrally buoyant." The animal had adjusted its ability to float just right so it could stay under at one spot without too much trouble.
Can you do this with the dropper in the bottle? If you squeeze the bottle just right, you can make the dropper go just halfway down and stay there. When you squeeze the bottle, the increased pressure pushes on the air bubble in the dropper. As you may have seen, the bubble in the dropper gets smaller as you squeeze the bottle. As the bubble gets smaller, more water enters into the dropper. When the dropper gets heavier, it sinks.
Next time you see a sea amimal under the water, think about how it is able to dive down and hover in one spot underwater. Maybe there is more to it than you think.
J.J. logo © 1997 SeaWorld, Inc. All rights reserved. Used with permission.