Our science activities today are inspired by a lively guessing book, Whose Egg Is This? by Lisa J. Amstutz. 
The premise of the book is to guess who laid the eggs in the large, colorful photograph on the left page by matching them with one of the four animals in photographs on the right page. Fortunately, each page comes with plenty of helpful hints, so even if the child doesn’t recognize the egg, he or she will likely be able to figure it out. Answers are also provided in the back.
This is a great format for a children’s book. It encourages children to observe closely and it engages their curiosity. It is fast-paced and fun. It is sure to inspire more activities and experiments like these:
Activity 1. Who is oviparous?
Oviparous means an animal that lays eggs. (Technically, lays eggs without further development of the embryo while it is in the mother.)
Brainstorm to create a list of different animal groups with egg-laying females.
Birds are probably the first to come to mind. They are the only animal group where all the members lay eggs.
What other vertebrates lay eggs?
What about
- reptiles?
- amphibians?
- fish?
Can you find any exceptions, like snakes that give birth rather than lay eggs?
Turtles and tortoises lay eggs.
What about mammals? Mammals that lay eggs are in the group called monotremes, which include the platypus and echidnas.
Do any invertebrates lay eggs?
At least some species of
- Insects
- Spiders
- Crustaceans, like lobsters
- Some molluscs, like snails
- Flatworms
- Earthworms
- etc.
Can you think of any others?
Activity 2. Compare and contrast the eggs of various animals.
Look at photographs of different types of eggs.
How are eggs that are laid in the water different from those laid on land?
Are all eggs covered with a hard, rigid shell?
Are they all the same size?
What about color?
Do you know whose eggs were in the photographs? (Answers at bottom of post).
3. Investigate egg anatomy
Surprisingly, an egg can be quite complex inside. There are multiple layers and structures.
(Illustration by Horst Frank at Wikimedia)
Schematic of a chicken egg:
1.   Eggshell
2.   Outer membrane
3.   Inner membrane
4.   Chalaza
5.   Exterior albumen (outer thin albumen)
6.   Middle albumen (inner thick albumen)
7.   Vitelline membrane
8.   Nucleus of pander
9.   Germinal disk (blastoderm)
10.   Yellow yolk
11.   White yolk
12.   Internal albumen
13.   Chalaza
14.   Air cell
15.   Cuticula
The Exploratorium has a series of egg-vestigations for looking inside an egg, including
4. The Color of Bird Eggs – In the News
Birds eggs come is an astonishing array of colors.
Poster of bird eggs – (Note:Â This poster does have stylistic diagram of a bird’s internal reproductive organs, in case you aren’t ready to go there )
Scientists have begun to realize that the color of bird eggs may be about more than just camouflage and there has been a recent burst of studies examining various aspects of color and speckling patterns.
For example, speckling may add structural support to the shell and as well as protection from direct exposure to the sun. The speckles may protect against ultraviolet rays while allowing enough light it so the chick inside can adjust its internal clock. Or the speckles may absorb heat and help maintain temperatures when the incubating parents are away from the nest.
Ornithologists (scientists that study birds) have found that species that are the target of nest parasites, like cowbirds, are sometimes better able to recognize the color patterns of their own eggs than species that aren’t as susceptible.
It seems likely that how egg color works will differ between different species of birds and may serve more than one purpose. Sounds like some great potential for science fair projects.
To study bird egg speckles with youngsters, try this craft to make artificial speckled eggs. See if eggs with speckles or without are easier to find when hidden in the grass.
If you are interested in participating in a citizen science project, Caren Cooper put out a call for photographs of the eggs in house sparrow nests last year. The speckling of house sparrow eggs varies quite a bit. The instructions ask that you include a white piece of paper and a penny in the photograph for scale.
References:
Wired magazine has a popular science article “Debate Over Purpose of Bird-Egg Coloration Continues”
For a scientific review, see CHERRY, M. I. and GOSLER, A. G. (2010), Avian eggshell coloration: new perspectives on adaptive explanations. Biological Journal of the Linnean Society, 100: 753–762. available online
If you have early elementary-aged children, be sure to take a look at Whose Egg Is This? by Lisa J. Amstutz.
Paperback: 32 pages
Publisher: Capstone Press (January 1, 2012)
ISBN-10: 1429678542
ISBN-13: 978-1429678544
This book was provided by the publisher for review purposes.
(The eggs in photographs are frog eggs and snail eggs.)
