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)
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.