Category: Deserts (Page 2 of 2)

All About Lizards

Our post today is inspired by a book I spotted at our local library: Sneed B. Collard III’s Most Fun Book Ever About Lizards by, you guessed it, Sneed B. Collard III (for a full review, see Wrapped in Foil).

We have many different kinds of lizards here in Arizona. I love how this book starts out with an introduction to “Joe Lizard,” a western fence lizard, which is the kind we see in our yard all the time. The author also discusses other lizards common to Arizona, such as Gila monsters, horned lizards and western whiptails.

What are lizards?

Lizards are reptiles with over-lapping scales. They also have moveable quadrate bones that allow them to open their mouths very wide. Finally most lizards (but not all) have legs, which distinguishes them from the snakes.

Lizards also have the ability to drop their tails if they are attacked by a predator. You can see the discolored area of the tail where this one has just grown its tail back.

Western fence lizards can be found climbing on trees, where they lend in perfectly with the bark, as well as on fences. The males have bright blue bellies, which they show off by doing push-ups.

Whiptails have particularly long and slender tails.

Collared lizards, named for the black band at their neck, are often brightly-colored.

Activity 1 :  Lizard body temperature

Lizards and other reptiles are ectothermic, which means that their internal body temperature is controlled by the temperature of the environment around them. Another word for this is “cold-blooded,” although lizard don’t really have cold blood. Lizards move from sun to shade and place to place to keep their temperature in the optimal range.

Children may assume that when the outdoor temperature is 78° F, it is the same temperature everywhere. In fact, many surfaces will be colder or warmer than the air temperature depending on sun exposure and other factors. These differences are called “microclimates.”


  • Thermometers (enough for every participant, if possible.)
  • Lamp (if doing this activity indoors), or sunny day outdoors
  • Dry play sand (or soil if not available)
  • Water
  • 2 containers to hold sand (enough for small groups of participants to share)
  • Timer or watch
  • Pencil and paper

Place a similar amount of sand into each container. Moisten the sand in one of the containers with water. Set both containers in the shade or indoors with the lamp off for a a few minutes to allow it to stabilize. Now take the temperature of the sand just under the surface with the thermometer for both containers and record the results.

Move the containers to a sunny place or under a lamp. Take the temperature after five minutes and again after ten minutes. Did it change? How did the temperature of the wet sand change in comparison to the dry sand? (The temperature of the wet sand should change less than dry sand).

If outdoors, encourage the children to check and record temperatures in several locations, both in the shade and in the sun.

If you were a lizard that should have an internal temperature about 80 °F, where would you spend your time? How about if your preferred temperature was 90°F?

What do lizards do when it is too cold out? Our Arizona lizards hibernate during the coldest months of the year.

Activity 2. Lizard in the Sun (Under a lamp)

See how a “lizard” absorbs heat. Appropriate for younger children.


  • Two lizard shapes cut from black construction paper
  • Small desk lamp

Place one lizard shape directly under the lamp and one at least three feet away, preferably in a shaded or dark area. Have the children compare the temperature of each.

(Older children could record the temperature difference with a thermometer.)

Optional: Added graphic of temperature vs. lizard activity on page 3 from Sonoran Desert Museum’s Leaping Lizard’s handout.


(See more activities for preschoolers in our newer post.)

Citizen Science:  More opportunities for studying lizards

And don’t forget,

Sneed B. Collard III’s Most Fun Book Ever About Lizards

Hardcover: 48 pages
Publisher: Charlesbridge Publishing (February 1, 2012)
ISBN-10: 1580893244
ISBN-13: 978-1580893244

Disclosures: The book was from our local library. Also, 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.

Where is your favorite place to watch lizards?

(*Note: It was entirely the lizard’s own decision to climb up this person. It was not picked up or handled.)

Desert Tortoises

Our science this week is inspired by the children’s picture book Desert Tortoises by Elizabeth Thomas. It introduces first grade level beginning readers to desert tortoises with big, close-up color photographs, short sentences and controlled vocabulary. Children will learn what a desert tortoise is, what it looks like, where it lives, and even its life cycle. It is a great book for youngsters interested in nature who want to read for themselves.

What exactly is a tortoise? Tortoises are reptiles that live on the land, whereas turtles live in the water for the most part.

Desert tortoises (Gopherus agassizii) are fascinating creatures only found in the deserts of the southwestern United States and northern Mexico. They have large, scaly front legs for digging.Their shell or carapace is dark brown with deep lines.

We met this desert tortoise at a class at the Desert Botanical Garden in Phoenix.

We learned a lot about tortoises in the class, including that you should never pick up a wild tortoise. It turns out that one way a tortoise survives in such a dry environment is by holding urine in its bladder and recycling the water from it. If someone picks up or otherwise scares a desert tortoise, part of its defense is to urinate. Studies have shown that unless the tortoise can quickly replenish the supply of water that it lost by urinating, that it is likely to dehydrate and die. Just shows that simple human curiosity can be fatal to other creatures and that we need to be respectful of wild animals.

We also learned desert tortoises that have been brought into captivity should never be returned to the wild because they potential carry diseases that might infect wild tortoises.

Other desert tortoise facts:

  • They can live up to 100 years.
  • The females don’t lay eggs until they are at least 15 years old.
  • They dig burrows in the soil to stay cool in the hot summer.
  • They eat desert plants such as cacti.
  • They hibernate in the winter.

Activity 1. Desert Tortoise Drawing


  • Art supplies such as crayons, colored pencils and markers
  • Photographs of desert tortoises, from books or the Internet
  • Drawing paper
  • Optional: coloring sheets to print out

Encourage the children to examine the photographs closely and draw a scene with a desert tortoise. For more formal instructions, try how to draw a desert tortoise.

Activity 2. Learning the life cycle

Like many reptiles, tortoises hatch from eggs. You can see the eggs, hatching and young tortoises in this video.

As the narration points out, the young tortoises spend time after hatching absorbing the remains of the egg yolk as an important source of nutrition.

Young tortoises grow slowly over a period of years. There are physical differences between the males and females in the shape of the carapace, etc.

For much more information, see this detailed life cycle of desert tortoise.

So, do you think they are cute and that you might want to have a desert tortoise as a pet?
Consider these facts first:

1. You will probably have to leave your tortoise to someone in your will, because if you care for it well, it is likely to outlive you.

2. You won’t be able to see it all winter, because it needs to hibernate.

3. You need to supply it with specially selected food. The fruits and vegetables we eat contain too much water and chemicals that can harm tortoises.

4. You will need to find someone else to care for it if you can no longer do so. You can’t just let it go because it won’t survive and it is likely to carry diseases that will harm other tortoises. Besides, it is illegal to do so.

The Arizona Game and Fish Department has more about rules and care of desert tortoises.

As with any animal, it is really important to do your research before adopting a pet. With care, many people are quite successful when they adopt captive-bred animals.

If you are really interested in desert tortoises, “get out of your shell” and learn more about them. Then, pass on what you find out to your friends.

Be sure to check out Desert Tortoises by Elizabeth Thomas and other great books about desert tortoises.

Reading level: Ages 4 and up
Library Binding: 24 pages
Publisher: Capstone Press (August 1, 2011)
ISBN-10: 1429666455
ISBN-13: 978-1429666459

Book was supplied by publisher for review purposes.

Looking for STEM books for children? Check the STEM Friday round up each week for recommendations.

STEM Friday is hosted today at Simply Science.

Newer posts »