Tag: seawater science

Beach Science: Algae

This week we are continuing our series at the beach. Check previous posts for sand science and seawater science.

Have you ever found something plant-like on the beach and wondered what it was?


beach stuff

Seems like a lot of beach plants are hard to classify. Are they algae, a sort of seaweed, or are algae and seaweed the same thing? Are algae plants or do they belong to a different kingdom? These are all good questions, and scientists are just beginning to answer some of them.

Many of the plants and plant-like creatures you see at the beach are technically algae. For example, kelp are giant brown algae.



Algae come in many colors, like these red ones.


The green algae are often found in freshwater ponds and lakes.


Ready to learn more? Here are some suggestions for activities to investigate algae. I’d love to hear your ideas, as well.

Activity 1. Make an algal collection

Gather algae on the beach and keep it moist in seawater. If you have never worked with algae, the Hawaii Botany Department tells you how to make an algal herbarium. Or if you don’t want to disturb nature, you can take close up photographs of what you find.

Once you have a collection, visit these websites to help you identify what you have.

Michael Guiry’s Seaweed Site covers all things seaweed and the identification of algae.

Life on the Australian Shores and Algae: The Forgotten Treasure of Tidepools are also helpful, although the later tends to get a bit silly at times.

You may be wondering why anyone would care about algae. Turns out, algae are important in a lot of ways.

Activity 2. Investigate food chains.

Algae are the basis for aquatic food chains in both seawater and freshwater.

If you are unfamiliar with the concept of food chains, this book is a great introduction to food chains and food webs. It has been a family favorite.

Who Eats What? Food Chains and Food Webs (Let’s-Read-and-Find-Out Science, Stage 2)by Patricia Lauber and illustrated by Holly Keller

Find out as much as you can about food chains in the oceans. Gather, print and cut out pictures of ocean critters to illustrate your own posters of food chains or webs.

Activity 3. People eat algae too.

You have probably eaten algae and didn’t even know it. Carrageenan, a thickener used in a variety of foods, is extracted from a red alga. For more information, see http://encarta.msn.com/encyclopedia_761573848_3/algae.html.

Once you have an idea what to look for, head to your kitchen and check to see if you have any foods that contain carrageenan or other products made from algae. Look at the cookbook listed below (or a similar one), and make some of your own dishes using algae. Asian markets are often an excellent source of ingredients.

If you are interested, a fun research project would be to investigate all the ways people use algae for food throughout the world.

Activity 4. Other important uses for algae.

See if you can make a list of other uses for algae. Here are some I found:

Algae are thought to make much of the oxygen we breathe.

This video shows a camera zooming in on the leaves and then the cells of a common water plant, Elodea. In the cells you can see the chloroplasts moving around. The chloroplasts are the sites of photosynthesis, the process that turns sunlight into chemical energy we can use as food. A by-product of photosynthesis is the release of oxygen. Although Elodea is actually a vascular plant, the process in green algae is the same.

If providing food and oxygen weren’t enough, now scientists have discovered ways to use the oils found in algae to make biodiesel. In fact, algal oils can be made into jet fuel. See this previous post for more information about algal research at ASU.

If you are interested in algae, here are a few books you might want to try:

The Seaweed Book: How to Find and Have Fun With Seaweed by Rose Treat and Randy Duchaine

For Adults:
Seaweeds of the Pacific Coast: Common Marine Algae from Alaska to Baja California
by Jennifer Mondragon and Jeff Mondragon

Have fun with some seaweed science and let me know what you discover!

Edit: To check the rest of the posts on beach science, follow these links:

Sea Horses and Other Fish

Shore Birds

Tide Pool Invertebrates

Beach Science- Boats

Beach Science-Sand

Beach Science-Seawater

Weekend Science Fun: Beach Science – Seawater

Is there a trip to the beach in your future this summer? Although trips to the beach are mostly pure fun, that doesn’t mean you can’t include a little science. Prepare for seashore science activities ahead of time and your children will have even more to discover when you get back home.


What do you usually see at the beach? Of course you’ll see sand, rocks and water. If you are lucky you may also spot some wildlife and algae. Over the next few weeks we are going to have a series of science discussions, experiments and activities on things you find at the seashore.

This week:  Seawater Science

It doesn’t take long at the beach to discover that seawater is salty. You can taste the spray on your lips. Ever wondered why seawater is salty or what is in it that makes it taste salty? There really is science in seawater.

1. Seawater pH

One easy experiment is to take along some pH paper and check how acid or basic seawater is. Compare it to other substances and to tap water.

Typically seawater is basic, that is higher than 7.0. Seawater pH is an important aspect of its chemistry because it impacts such processes as the laying down of calcium by corals.

2. Seawater salts


  • Seawater
  • Plain water
  • 2 similar stainless steel or glass pans, or better yet, beakers
  • Heat source like a stove
  • Potholders

With the help of an adult, bring one cup of seawater in one pan and one cup of tap water in another pan to a boil. Turn down the heat and simmer until the water is almost dry. Watch carefully. Try not to let it boil completely dry because that will harm the metal of the pan. Remove from the heat and set in a warm place to finish evaporating away the water. What’s left?

Optional:  in a third pan place tap water and add a Tablespoon of salt. Boil as above. What happens when you evaporate the water in this case?

You should see a residue in the seawater pan. Pretend you are a chemist. How would you figure out what is in the residue?

One way is to do a flame test. When different chemicals are added to a flame, the resulting colors can give you information about what salts or elements are present. Here a trained chemistry teacher shows how this works.

Note: If you’d like to see how to do this, the book Fireworks by Vicki Cobb and Michael Gold (Photographer) has instructions for performing flame tests included as one of the activities. See Fireworks for the Fourth of July for a review.)

Using flame tests and other techniques, scientists have found over 70 elements in seawater.

How did those elements get into seawater? When I was young, I learned that the movement of freshwater over the earth’s crust picked up salts and carried them into the sea. Over time the salts built up because they are left behind when the water evaporates to move through the water cycle.

When I watched Going Deep on Scientific American Frontiers I found out that isn’t the only way salt gets in the ocean.

About thirty years ago, deep sea explorers found features known as hydrothermal vents along mid-ocean rifts. These are places on the ocean floor where seawater seeps into cracks in the crust. The water becomes extremely hot when it comes into contact with magma under the surface. It can’t boil, however, because of the extreme pressure at those depths. It dissolves some of the minerals from the crust and then flows back up into the ocean, carrying the dissolved minerals with it. Scientists have figured out that these vents are a significant source of the salts in the ocean.

A final process that provides salts to the oceans is the eruption of volcanoes under water. This is similar to the vents because the seawater is reacting with hot magma and lava, and dissolving some of the minerals in the liquid rocks.

Seawater is fascinating stuff and we still have a lot to learn about it.

Hope you have fun at the beach and watch out for those waves!

(Affiliate links go to Amazon)

For the youngest set:

Hello Ocean by Pam Munoz Ryan and Mark Astrella (Illustrator)

For older kids:

The Magic School Bus on the Ocean Floor by Joanna Cole and Bruce Degen (Illustrator)

Blue Planet: Seas of Life DVD

Note: the linked page has some video clips.

For Adults:

A Scientist at the Seashore (Dover Science Books) by James S. Trefil

Edit: To check the rest of the posts on beach science, follow these links:

Sea Horses and Other Fish

Shore Birds

Tide Pool Invertebrates

Beach Science- Boats

Beach Science Algae

Beach Science-Sand