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This week let's look at an awesome desert plant, the saguaro cactus.

The saguaro is one of the most striking inhabitants of the Sonoran desert, which is located in the southwestern United States.

Life in the desert is challenging. There is very little water and it can be extremely hot during the day. To survive, saguaro cacti use water more efficiently than plants growing in other climates, and they have ways to keep themselves cool.

Activity 1. Why Spines?
What do you see when you look at a saguaro? Do you see spines? As you might expect, spines have long been thought to protect cacti from animals that might eat them. Scientists began to wonder about the purpose of spines, however, when they realized some animals aren't deterred by spines and some cacti have soft spines that aren't much protection. Can you think of any other reason cacti might have spines?


  • clay
  • toothpicks
  • a small thermometer or device to record temperature
  • flashlight
  • ruler

Form the clay into a golf ball to tennis ball-sized lump. Place it on a hard surface that won't be harmed by contact with clay (that is, not on the carpet, folks :-)). Place the ruler against the clay. Hold the flashlight about two inches away from the clay for five minutes. You might want to set it up on a book so you don't have to hold it. Take the temperature at the surface of the clay in front of the flashlight every minute.

Then shut off the flashlight. Allow the clay to cool a bit and then stick toothpicks into the clay all over the side toward the flashlight, until it resembles a cactus. Now turn on the flashlight for another five minutes. Does the clay look any different? Take the temperature of the clay as close to the surface as you can, under the toothpick spines. Record the temperature once a minute for five minutes again. Did the spines cause any changes?

Scientists have found that some spines shade the surface of the cactus and/or act as radiators to keep the surface of the cactus cooler.

Activity 2. Waxy Coating

Many cacti have a waxy layer on the outside. What is it for?

  • wax
  • paper plates
  • napkins or paper towels
  • measuring spoon
  • water

Place a napkin or sheet of paper towel folded into fourths on each plate. Pour four Tablespoons of water on each napkin (give or take a Tablespoon, depending on the absorbency of the napkin). The napkins should be equally wet or damp. Tear off a sheet of waxed paper. Fold it in half and then wrap one of the napkins inside it, taking care to fold over the corners so no air can get in. Leave the wrapped napkin on one plate and the unwrapped napkin on the other. Come back the next day and feel how wet each napkin is. If you live in a moist climate, you might want to leave it two or three days. What do you expect will happen?

Activity 3. Print out and construct this wonderful
Giant Cactus Forest Diorama (scroll down) from the American Museum of Natural History.

Activity 4. Compare the plants and animals found at the Alice Springs Desert Park in Australia with those found in the Sonoran Desert (Scroll to the bottom and click on daytime life and nighttime life around a saguaro cactus.)

If you would like to learn more about the inhabitants of the Sonoran desert, just let us know.

Weekend science fun will be short this week because a few things are getting in the way. (Sick cat, sick computer, etc.)

To continue beach science, let's take a look at some other common visitors to the seashore. Grab an identification guide and some binoculars, and a camera if you want, and let's investigate.

sea gull

You may have seen sea gulls dozens of times, but have you really looked at one? Check out those pink webbed feet.

Investigation 1. How do the beaks and feet of shore birds differ from those of the song birds in your community? How are they similar? Ever seen a pelican at the beach?

shore birds

Shore birds always seem busy.

Investigation 2. What do shore birds eat?

Investigation 3. Do shore birds drink? Where do they get their water?

shore birds

Shore birds are often in big groups, like these cormorants.

Investigation 4. Why are shore birds often seen in flocks?

Investigation 5. Where do different types of shore birds nest?

(Hint for 4 and 5: think about bird movement or migration).

shore birds

Now lie down on the beach, close your eyes and listen.

Investigation 6. What sounds do shore birds make?

Hope you have fun discovering shore birds.

Drop us a note in the comments and let us know what you find out.

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

Sea Horses and Other Fish

Tide Pool Invertebrates

Beach Science- Boats

Beach Science Algae

Beach Science-Sand

Beach Science-Seawater

Have you ever explored a tide pool while at the beach?

tide-pool-8Do you remember wondering what some of the creatures are?

A majority of the animals you see in a tide pool are classed as invertebrates, which means they lack backbones (or more technically, dorsal nerve cords). Invertebrates include animals like


hermit crabs,

sea-anemoneand sea anemones.

Growing With Science Tide Pool Animals Craft

Activity: Making Clay Tide Pool Creatures

Today's craft helps hone observation skills needed to identify and classify the many diverse marine invertebrates.


  • Photos/drawings of various marine invertebrates such as the Invertebrate Guide at the Monterey Bay Aquarium (click on thumbnail images) or illustrations from some of the books below.
  • Toothpicks (if age appropriate)
  • Paint
  • Markers
  • Chenille and/or wax-coated wikki stix
  • Your favorite modeling compound such as salt dough or modeling clay

Basic salt dough is 1 cup of salt, 1 cup of flour and 1/2 cup of warm water mixed together and then kneaded. Shape the dough and let it dry. You can adjust the relative amounts of flour and water to suit your needs.

We used Crayola Model Magic, which we purchased with a coupon from a craft store.

(Affiliate link to Amazon)

Study the examples and then create your own models. You can push in toothpicks as spines, and chenille or wikki skix as legs.

Let the models dry and then paint and decorate them. You can use your models to create fun tidal pool scenes by adding rocks and/or construction paper algae.

Examples of tide pool scenes:


Want more information about animals found in tide pools? Try the books below. (Disclosure: I am an affiliate for Amazon. If you click through the linked titles or ads and make a purchase, I will receive a small commission at no extra charge to you. Proceeds will be used to maintain this self-hosted blog.)


Life in a Tide Pool (Rookie Read-About Science) by Allan Fowler

Simple, straightforward informational nonfiction that covers the tide pool habitat.

Age Range: 6 and up
Series: Rookie Read-About Science
Library Binding: 32 pages
Publisher: Children's Press (CT) (September 1996)
ISBN-10: 0516200313
ISBN-13: 978-0516200316

How to Hide an Octopus and Other Sea Creatures (Reading Railroad) by Ruth Heller

Ruth Heller's books about camouflage are delightful, with rhyming text and colorful illustration. Highly recommended!

Age Range: 4 - 8 years
Publisher: Grosset & Dunlap (April 29, 1992)
ISBN-10: 0448404788
ISBN-13: 978-0448404783

Seashells, Crabs and Sea Stars: Take-Along Guide (Take Along Guides) by Christiane Kump Tibbitts and illustrated by Linda Garrow

Introduces children to common tide pool animals, with tips for identifying 15 different kinds of seashells, 5 kinds of crabs and 7 kinds of sea stars. Suggestions for activities included.

Age Range: 7 - 10 years
Publisher: Cooper Square Publishing Llc (January 1, 1999)
ISBN-10: 1559716754
ISBN-13: 978-1559716758

What Lives in a Shell? (Let's-Read-and-Find-Out Science 1) by Kathleen Weidner Zoehfeld and illustrated by Helen K. Davie

This series is really outstanding. What Lives in a Shell? covers many animals found at the beach.

Age Range: 4 - 8 years
Publisher: HarperCollins; 1 edition (April 22, 1994)
ISBN-10: 0064451240
ISBN-13: 978-0064451246
What's in the Tide Pool? by Anne Hunter

The books in this series are small (approximately 5 inches x 5 inches). Each describe a few common animals in a given habitat.

Age Range: 4 - 7 years
Publisher: HMH Books for Young Readers (August 28, 2000)
ISBN-10: 0618015108
ISBN-13: 978-0618015108

In One Tidepool: Crabs, Snails, and Salty Tails by Anthony D. Fredericks and illustrated by Jennifer Dirubbio

This book includes rhyming text of the "house-that-Jack-built" format.

Age Range: 4 and up
Publisher: Dawn Pubns; 1 edition (August 1, 2002)
ISBN-10: 1584690380
ISBN-13: 978-1584690382

There are a number of books about a single group of invertebrates that are written for young children. For example:

Crab (Welcome Books: Ocean Life) by Lloyd G. Douglas

Age Range: 4 and up
Publisher: Children's Press(CT) (September 2005)
ISBN-10: 0516237403
ISBN-13: 978-0516237404

Sea Stars (Ocean Life) by Lola M. Schaefer

Age Range: 4 - 8 years
Publisher: Capstone Press (July 1, 1998)
ISBN-10: 0736882219
ISBN-13: 978-0736882217



A House for Hermit Crab (The World of Eric Carle) by Eric Carle

Growing and having to move are themes in this classic book about a hermit crab looking for a new shell to live in.

Age Range: 5 - 7 years
Publisher: Simon Spotlight; Reissue edition (May 13, 2014)
ISBN-10: 1481409158
ISBN-13: 978-1481409155

Don't forget to check for other posts in the beach science category here at Growing With Science.