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

Gather:

• 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.

Here are two photographs of the more familiar Large Milkweed Bug, Oncopeltus fasciatus, from the archives.

Most members of the group feed on seeds, and Large Milkweed Bugs prefer the seeds of milkweeds.

They also feed on the milkweed plant when there are no seeds available. The ones in the photographs are sitting on the flower buds of a butterfly milkweed.

As you might guess from the bright red and black warning coloration, milkweed bugs take up the same toxins from milkweeds as the monarch caterpillar does. Their colors say, “Don’t eat me!”

Surprisingly, Large Milkweed Bugs are commonly used for science experiments because they are fairly easy to take care of. If you don’t have milkweed seeds, they will feed on raw sunflower seeds as well as some nuts. They also need a good source of water.

Illinois.edu has more information and detailed rearing instructions.

Our seeds this week come from a plant that does not grow in the Sonoran Desert, but it is a shade-loving perennial favorite elsewhere.

Probably not many people grow them from seeds, which are found in seed pods on the flowering stalks.

These large, black seeds will produce a new plant, however. Do you know what that plant might be?

Camouflage and invisibility are two very different things. Camouflage is the use of color or other aspects of appearance to help an object blend with its environment. Invisibility, on the other hand, is changing the way light reflects or refracts when it hits an object and thus preventing the light from reaching our eyes. We literally can not see an object that is invisible.

Becoming Invisible: From Camouflage to Cloaks tells how scientists have been able to bend electromagnetic waves that are near relatives of visible light (see Exploring Light and its Relatives Part I and Part 2) with special man-made materials called metamaterials. Using metamaterials made of metal and fiberglass, scientists have been able to develop “cloaks” that bend microwaves and infrared light around an object, hiding it from detection. Very cool!

Activity 1. Hiding with color – camouflage for younger children

Read one of the books suggested below to introduce the idea of camouflage.

Gather:

• Fabric swatches of different colors and designs
• Painter’s blue tape (doesn’t leave a residue when it is removed, but it is more expensive) or masking tape
• Suitable area to play hide and seek, indoors or out

You might want to sort the children into teams if you are working with a large group. You will need enough swatches of fabric so that each child or team can hide a few different swatches. Make loops of tape with sticky-side out and then apply a few to the back of each swatch. Now select a child/team to be the hider. They will hide the swatch in plain sight in the play area by taping the swatch to items while the other children, who will be the seekers, close their eyes or wait in another area. When the hiders have applied their swatch, have the seekers come look for it. Once they have found it, change roles. The goal is to find a background object that matches the color close enough that the fabric is difficult to see, and thus takes longer to find.

Activity 2. Hiding with color- camouflage for older children

Gather:

• Paper
• Art supplies such as markers, crayons, colored pencils, etc.
• Painter’s blue tape (doesn’t leave a residue when it is removed, but it is more expensive) or masking tape (optional)
• Suitable area to play hide and seek (optional)

For older children, have them create their own camouflage patterns for different settings. You could also have the children do the hiding activity (1), but substitute their own designs on paper for the fabric swatches. Or figure out an experiment to test the effectiveness of various camouflage designs.

Activity 3. Making glass “disappear”

We don’t need high tech metamaterials to make an object invisible. We can hide a piece of Pyrex® glass by immersing it in a material that has a similar index of refraction, Wesson® oil.

Gather:

• small Pyrex® glass bowl
• A larger glass bowl
• Wesson® oil or baby oil, or a mix of the two

Place the smaller bowl inside the larger bowl. Fill them both with Wesson® oil, baby oil, or a mix of the two. Once covered with oil, the smaller Pyrex® bowl should disappear from view.

See a similar activity using a Pyrex® stirring rod and explanation from Exploratorium

Activity 4. Make jelly marbles disappear in water

Obtain some jelly marbles from science supply stores, for example from Steve Spangler. Soak the jelly marbles overnight in water. Then fill a clear glass container with water. When you drop in the soaked jelly marbles, they will disappear.

Jelly marbles are polymers that absorb water. When they are swollen with water, they have the same index of refraction and disappear when you place them in water.

This video shows examples of both of the index of refraction activities:

Isn’t that amazing?

If you try any of these activities, be sure to let us know what you find out.

Related camouflage links:

• Brain Pop Jr. has a unit on camouflage
• The Invisible Man
• The Arts of Deception at Mongabay.com (has ads)
• Survivors: How Does Color Protect Insects from Predators?

Children’s books about camouflage (title links go to Amazon):

	Becoming Invisible: From Camouflage to Cloaks (Great Idea) by Carla Mooney (is for ages 8 and up) My review
	Hiding in Deserts (Creature Camouflage) by Deborah Underwood My review
	Animal Planet Weird and Wonderful: Show-Offs (Animal Plant Weird & Wonderful) by Margaret McPhee is not just about camouflage, but all the ways animals use color. My review
	Where in the Wild?: Camouflaged Creatures Concealed… and Revealed by David Schwartz and Yael Schy, with photography by Dwight Kuhn My review
	Where Else in the Wild? is a enchanting combination of poems by David M. Schwartz and his wife, Yael Schy, and photographs by Dwight Kuhn. My review
	How to Hide an Octopus and Other Sea Creatures (Reading Railroad) by Ruth Heller
	How to Hide a Butterfly and Other Insects (Reading Railroad) by Ruth Heller.
	What Color Is Camouflage? (Let’s-Read-and-Find-Out Science, Stage 2) (Let’s-Read-and-Find-Out Science, Stage 2) by Carolyn B. Otto and illustrated by Megan Lloyd

The larval stage are called wireworms. They live in the soil, often in sod.

Here’s an example of a wireworm. We dug up from the soil. The reddish-brown end to the right is the head.

In this photograph, the wireworm has been tipped on its side so you can see the three tiny pairs of legs on the thorax, which is the part right behind the head. At the other end (end of abdomen) is a single proleg.

The end of the abdomen is towards the right in this photograph. This species has a flattened area above the single peg-like proleg.

The flattened area has numerous hairs, so it probably has a sensory function, although it also looks a bit like a second head.

It is amazing what you see if you (dare to) look closely.

It is our 100th Mystery Seed of the Week!

To celebrate, let’s take a look at a few of our readers’ favorite seeds and seed pods over the past two years.

Starting out, Katherine says these bottle tree (Brachychiton) seed pods have wonderful boat shapes.

She makes intriguing felt crafts with them, including a darling felt sprout at One Inch World blog.

Not surprisingly, many of the fan favorites had to do with food.

Both Rebecca (of Rebecca in the Woods) and Mike (of Slugyard) shared Indian-inspired recipes for the chickpeas (also called garbanzo beans). Rebecca suggested cholay (curried chickpeas) and Mike chimed in with “…Indian chili. It has chickpeas, onions, garlic, tomatoes, ginger, and a tad bit of cashew nut butter (peanut works fine too). Oh, and ground lamb, and a bay leaf, turmeric, coriander, cumin, and garam masala. Delicious!”

Just writing this makes me hungry.

Note:  the chickpeas in the photograph are actually dried seeds, ready for planting. That might be why they were difficult to recognize.

Cranberries also sparked a lot of interest.

Eamon believes cranberries are great in smoothies. I hadn’t thought of that, but people do drink a lot of cranberry juice, so I went looking for a recipe. I found a great one that took soymilk, cranberries, honey and half a banana. Very refreshing served over ice. Great suggestion, Eamon.

Lynne sent me a recipe for cranberry salsa. She says,

“You can use plain cranberry sauce from the store or make your own.
Add chopped jalepeno, 1 medium or more if you like it hot.
Chopped cilantro
Chopped green onion 1 or 2, mix.
…This is yummy over cream cheese, it makes a nice appetizer.”

Wow, thanks for sharing, Lynne!

I would also like to thank my cousin Karen for all her contributions to this blog, including this lovely mimosa flower. Karen blogs at Musings, Mischief and Mayhem and Leaping From The Box.

Looking back, we have covered some common seeds and some unusual ones. One of the most unusual seeds we have covered is from the tipu tree.

It is a legume with a seed that looks like a maple key. Very cool!

Does anyone remember our very first mystery seeds, from way back in November of 2009?

Thanks to everyone who has left comments and sent notes. You are a great community!

And, if you have any suggestions for upcoming mystery seeds I would love to hear them.

I was hoping someone would notice that the tree was lacking pine needles or leaves, although it had cones.

Here is the same tree in the summer. I love the soft, lacy foliage.

Larch trees are unusual conifers, because they are deciduous. The trees lose their needles/leaves in the winter.

Tamarack larch trees grow throughout the Northeast. They are very cold tolerant. Related species grow in northern Canada, Russia and northern Europe.

Look at the fall color of this stand of tamarack larch (by Linda Baird-White at Wikimedia)!

Have you ever seen a tamarack larch? Where was it growing?

We are excited that Arizona is participating in a big way this year. The Arizona SciTech Festival will showcase science, technology and innovation through a series of over 150 free events taking place between Jan. 25 and Mar. 14, 2012 statewide.

According to their news release, over 250 organizations have partnered together to promote Arizona’s participation in science, technology, engineering, and math (STEM) through a series of hands-on activities, workshops, conversations, debates, exhibitions, concerts, guided walks and tours.

Featured Events Include:

• Jan. 25 – 26 Aerospace and Defense Requirements Conference (Not free)
• Feb. 3-5 Glendale Chocolate Affaire-The Science of Chocolate
• Feb. 4 Arizona Science Center’s Innovations in Bioscience
• Feb. 10–12 Mesa’s Take Flight Celebration
• Feb. 14, 16 AZ Renaissance Festival’s Discovery Days
• Feb. 16 Chandler’s Tech Crawl
• Feb. 16 Tempe’s The Science of Fun
• Feb. 18 Tucson’s Science in the City
• Feb. 19–20 Challenger Space Center’s John Glenn Anniversary Event
• Feb. 21 A Day of Dean Kamen
• Feb. 25 Arizona State University’s EX-STATIC at New College
• Feb. 25–26 Scottsdale’s Science of Baseball
• Mar. 3 Arizona State University’s Night of the Open Door
• Mar. 6 University of Arizona’s Innovation Day

Wander through the Arizona SciTech Festival website to find many more fantastic activities. (There are almost too many to choose from.)

If you aren’t going to be in Arizona in time to take part, try these related festivals:

• Bay Area Science Festival- going on now!
• Philly Science Festival
• NC Science Festival
• San Diego Science Festival
• Cambridge Science Festival
• Flagstaff Festival of Science

If you go to any science festival events, please drop us a comment and tell us about it.

Glancing quickly, I thought the read and black bug below feeding on a desert milkweed flower was a large milkweed bug, Oncopeltus fasciatus.

But looking again, I realized it had two black bars across the center of the body, rather than one wide one.

This is an adult Oncopeltus cayensis. I don’t think it has a common name. Check out the sucking mouthparts it is using to feed on the flower.

Have you ever found something new when you took a second look?

Our mystery seeds this week are actually the cones that hold the seeds.

These are from the Northeast, rather than from the Southwest. The tree has some unique characteristics, as you might guess from these photographs. Do you know what kind of tree these are found on?

Note:  We are quickly approaching our 100th Seed of the Week. To celebrate, I’d like to feature your favorite seed. Please send me the name of your favorite plant or seed and your first name to growingwithscience (at) gmail. com by January 19, 2012 and I’ll create a list. If it is an unusual plant, please let me know a little about it, too.

Looking forward to hearing from you!