Module 11: The Invertebrates of Kingdom Animalia; Apologia Biology
Symmetry: balanced proportions; also : beauty of form arising from balanced proportions.
Beauty of form arising from balanced proportions? T or F
Let’s investigate this questions.
There are three kinds of symmetry:
- Spherical symmetry. Ex. Volvox or ball. You can slice it in half any way you want and you’ll have two identical sides.
- Radial Symmetry – Can be cut into two identical halves by any longitudinal slice through the center. Ex. Sea Anemone, Jelly fish, flowers, pineapple.
- Bilateral Symmetry – Can be can be cut into two identical halves by a single longitudinal slice. Right down the middle. Ex. Flatworm, straw, humans. Humans!? Really?
To find out if we humans have “identical halves” and we are beautiful due to balanced proportions, I took mug shots of my students.
I then took the photos and flipped them left to right. The original photos and the flipped photos were printed for each student.
I made a longitudinal slice from top to bottom of each photo and handed them to the students. The first two slices were the original photo and the students placed them together. They liked what they saw, but couldn’t figure out what I was doing with them. 🙂
Next I handed them the flipped photo and instructed them to take the left side and place it next to the left side. Do the same with the right side.
The screams, giggles, and OMG! Were priceless. LOL Are we identical? No, God did not make us that way and let us be thankful He did not.
Do we have bilateral symmetry? Yes, but each side is not identical.
Are we beautiful? Yes! God has made us beautiful just the way we are and let us be thankful for that.
To find out what we did last year and get some awesome links, go here.
Here are some links to addition videos for this module.
- Filtering action of a sponge. Sponges possess no symmetry.
- Nematocysts going off. Phylum Cnidaria have radial symmetry.
- Regeneration of Planaria parts. Bilateral symmetry. Very cool video.