Last week we finished our unit study of the world's oceans. We had a surprise or accidental experiment last night when the girls notice that one of those starfish toys that you put in water and it swells to way larger than it was to begin with had shrunk. It had been sitting in a bowl of water for the past week. They couldn't figure it out because a few days ago it had increased to three times the original size. They kept questioning why it had suddenly shrunk. Then McKenna looked at the water. That's when we discovered that little Miss McLarin had added salt to the water. A lot of salt!
We did a little investigating and learned that this was due to osmosis. When the toy had increased in size water was more abundant in the cells or fibers of the toy. Adding salt caused the water to be drawn into the salt water and out of the toy. The toy had more water and less salt and the water outside the toy had way more salt. Apparently the cells of this toy starfish were trying to equalize the amount of water inside and outside of itself.
The girls starfish toy has shrunk a size or two from the size it was a few days ago, but is still larger than when it was put into the water. How's that for a cool accidental experiment?
The picture of me holding the toy starfish
helps show the actual size of the starfish.
When it was put into the water it was about
3" across. It then swelled to about 9" across.
Now after the salt was added to the water
Can you see that big pile of salt under the starfish?
it has shrunk to about 5-6". Sorry I don't
have a picture of it when it was at it's
largest size. Hope you enjoyed sharing
in our fun learning experience!
Is a starfish a fish? Have you ever had your kids ask you that question? Did you know the
answer? I'm pretty pleased that I knew the answer to that question at least, but I
learned today there was a lot about starfish that I didn't know.
Starfish or Sea Stars are not a fish. They don't have gills and they
don't even have a brain, but they are a living animal.I started off looking up information on starfish and became so engrossed in the subject myself I just knew the girls would enjoy this part of our Ocean Unit. One thing we learned that we didn't know was that not all starfish have five arms. Depending on the variety they can have up to forty arms!
We discovered starfish can be as small as half an inch in diameter to as large as up to 2 feet across. They can weigh as much as 11 lbs. There are over 2000 varieties of starfish! Next the girls wanted to know where they lived. McKenna was sure they only lived in warm waters. She was surprised to learn that they live not only in intertidal pools and tropical waters, but even the cold arctic waters.
We learned they eat small fish, clams, mussels, snails, and coral. It was surprising that they can eat a meal consisting of the sizes of some of these other creatures. We learned the way they do this is by shoving their stomach out of their own mouth and digesting the food. They then pull their stomach back in their mouth and finish digesting their meal. Starfish have two stomachs and their mouth is on their underside in the middle of their body. I demonstrated this for the girls by using a small plastic bag and grabbing a seashell and pulling it back inside the bag. McLarin said if she ever pushed her stomach out of her own mouth to eat that would be disgusting! She would be sick as a dog. HeeHee!
We also learned that starfish have eyes. Not eyes that see visually, but eyes that can sense light and dark. They are located on the ends of their arms and are called eyespots.
They move from place to place using their tiny tube feet. As I mentioned earlier we learned starfish have no brains. They also have no blood! They are able to use a vascular system that uses water that they pump into their tube feet to inflate them. Starfish can lose an arm and are able to grow it back. Or regenerate it. We learned what the term regenerate means today. Starfish can save themselves by losing an arm to get away from a predator and growing it back. They are able to lose up to three arms without dying. They also live up to thirty-five years if they don't have an accident, get eaten or get sick. We learned so much today about starfish. We have decided to learn more about them tomorrow.
We watched this video about starfish regenerating a lost arm.
We also watched this next video about the dissection of a starfish.
Our last video of the day was one showing a strange variety of starfish called the Crown Of Thorns.
Some of the other resources we used was the Sea Star unit study at .Homeschoolshare. We also found a a site that explained the anatomy of a starfish with diagrams. We used wikimedia and About.com to look up information on starfish. Probably the most amazing webpage we visited for information was the National Geographic page. It had lots of beautiful pictures of many different varieties of starfish. I also found this picture of the tiny tube feet of a starfish.
Aren't those tiny and delicate looking?
I decided to continue with the starfish theme with math for McLarin. I found the idea for a starfish counting game for math here. McLarin was tickled pink to play this with me and her daddy. I like that it was a fun way for her to learn number recognition. I found a starfish craft at on this blog and plan to do it with the girls tomorrow. Of course we needed some coloring pages and I found a host of them here to download for free. Another craft your kiddos might enjoy I found here.
Some books about starfish you might enjoy using.
The book below has lots of information on starfish and would be fairly easy for a beginning reader.
If you decide to study starfish I hope you have as much fun as we did. Starfish are amazing creatures and are a marvel of God's handywork.
.jpg)
