Talking About Sand Dollars
I recently visited a second grade classroom to talk about sand dollars, sand, and the beach.
We started out by taking a photographic “walk on the beach” to get an idea of what you might find on a typical morning beach walk on the Oregon coast.
Then we took a closer look at one of my favorite finds: sand dollars.
This is a sand dollar that is still alive. They are typically darker, and range from purple to green in color.
- Sand Dollars are classified as Echinoderms, and are related to sea stars and sea urchins.
- The furry appearance of the live sand dollar is actually a dense covering of mini spines and tube feet. They move, eat, and breathe using these tube feet.
- Specialized tube feet are located in the area of the star pattern and are used for respiration.
- Sand dollars live (on average) 10-13 years.
- Age can be determined by counting growth rings.
Here is a video I took of a live sand dollar, showing the mouth and moving tube feet:
Above is a sand dollar shell, or “test,” below is the underside view.
A closeup of what the underside of a sand dollar looks like.
- The large hole is the mouth.
- The “veins” are actually food grooves. The tube feet move food particles captured anywhere on the body along these grooves (with the help of mucus) to the mouth.
- The small hole is where waste passes.
Sand Dollar teeth!
- Sand Dollars have 5 teeth, called Aristotle’s lantern.
- Sometimes these teeth are referred to as “doves.”
- It may take up to two days for a sand dollar to chew its food.
In The Classroom
Each student chose two sand dollars. One to keep, and one to break open and explore.
My idea was that they could take both shells home then break one open with their families to share in the fun. A nice idea, but the idea of not breaking open a shell right then and there was too much to bear, especially for some of the boys. Smash!
First we took a closer look at sand dollar anatomy.
Then we broke them open! Some students did the job delicately…
Others had lots of fun doing the breaking part. 🙂
We also talked about sand. Oregon beach sand contains a lot of components, one of them being the mineral magnetite. It is attracted to magnets, and it is a mini magnet in itself.
We had lots of fun playing in the sand…
I love the innate creativity of kids!
Sand Dollars Part 3…?
I am going back soon to do “an art project” with sand dollars, but I am at a loss as to what that will be at this time.