Experiment of the Week - #179 Got Wrinkles?
Wow! I have just finished an
incredible week of digging dinosaurs. I thought I knew a lot about
dinosaurs, but I learned more about dinosaurs this week than I have in the 38 years
I have been a dino nut. (I started when I was 5.) Dr. Robert Bakker is an
Another reason that I had a good
time was that I found some neat fossils. Of all the specimens that I found,
the one that I am most excited about is a tooth. It is from a Megalosaur
called Brontoraptor, and it was a BIG meat eating dinosaur. The tooth that I
found was in a site where no Megalosaurs had been found and was higher in
the Como Morrison formation than any Megalosaurs have been found.
Because it was a special specimen, I got to give it a name. You may have
heard about the T. rex named Sue at the Field Museum. I named this Brontoraptor
Alicia, after my wife. She was wonderful enough to let me go off for a
week of digging and I wanted her to know that I was thinking of her.
This week's experiment comes from
a conversation we had while driving to the site one morning. My friend Scott
asked why your fingers get wrinkled when you are in water for a while. You
have probably noticed that when you wash dishes, your hands get very
wrinkled. (You do help with the dishes, don't you?) As I explained what was
happening, he asked an even better question. This experiment will give the
answer. You will need:
* two glasses
* warm water
Fill each glass 2/3 full of warm
water. Mark one "water" and mark the other "salt water." Leave the "water"
glass as it is. Pour salt into the "salt water" glass and stir. If all of
the salt dissolves, add more. Keep adding until no more will dissolve.
Place the glasses on a table,
beside each other. Place one finger into the "water" and another finger into
the "salt water." Your fingers should be in the water at least up to the
first joint. Now sit there and wait......... Keep waiting......... Not
yet......... Almost done......... After 5 minutes, take your fingers out of
the water and compare them. You should find that the plain water finger
is more wrinkled than the salt water finger.
Why? What makes your finger
wrinkle? Each of the cells in your body is like a tiny water balloon. There is a
membrane surrounding the cell, much like a rubber balloon. This membrane
will let water move through it, but the direction the water moves (in or
out) depends on salt and other dissolved chemicals in the water. The water
will move towards the highest concentration of salt. If the
salt is more concentrated on the inside of the cell, as with the plain water,
then water moves into the cell. This makes the cell bigger. If all of the
skin cells on your finger get bigger, you wind up with a skin that is too
big for your finger. This extra skin makes the wrinkles. Don't worry. After
your finger has been out of the water for a while, then the skin will
shrink back into place.
At this point, Scott asked his
wonderful question. He asked if that meant that you would not get as
wrinkled if you swam in the ocean. He was exactly right, as you can see from the
finger that was in the salt water. With more salt in the water, less of it
moves into the cells. Your finger skin does not get much bigger and you get
far fewer wrinkles. Before all of you adults get excited, no, soaking in salt
water will not cure the wrinkles you get as you get older.