This week was exciting for many of our students. They had been requesting some dissection activities and this week we delivered. If any of you are interested in trying some dissections on your own, Home Science Tools offers several preserved specimens. Keep an eye out for their dissection sales as well. We liked the variety of their specimens and the fact that they rinse the formaldehyde out of their specimens, which helps limit the smell. They also came with great dissection guides. Students were given extra reminders about safety in the science lab this week and all students wore gloves before handling any specimens.
Before we started dissecting, we had to discuss a few important terms. We introduced anatomical position so that we could find anterior, posterior, dorsal and ventral. Then for fun, we added the terms pronate and supinate, using the idea of a cup of soup and protecting the soup to help remember those terms. Then, because of the specimens we chose, we talked about vertebrates and invertebrates.
We started our week with a clam and a starfish. We prepared these specimens beforehand, as we had to do quite a bit with the scalpel to open the clam. We identified muscles, the foot, the mouth and the intestines in the clam. We noted the tube feet on the exterior of the starfish, as well as the sieve tube. Inside the starfish, we pulled out the digestive materials to find more of the tubes.
We continued our examination of invertebrates, moving into more traditional exoskeletons. We examined a grasshopper and a crayfish. The crayfish was large enough to more easily recognize some of the major organs, which was interesting as the stomach takes up a large portion of the head, which means it was easy to mistake it for the brain, which was hiding behind the stomach.
Our last invertebrate was the worm, which is full of tubes, from its tube brain and heart, and mostly intestines. For our first vertebrate, we dissected a perch. This is the first specimen we dealt with that had a brain large enough to really recognize. It also had bones to deal with, gills, and an interesting organ – a swim bladder.
The students were most excited about our last dissection of the week – the frog. The frog is great, because it has more similar organs to ours. The fat is interesting to notice. Some of the students asked about the bones, so we dug around in the leg to find the bones, finding the femur and tibula (which is the fibula and tibia combined). We also noted the thick muscle of the legs. The frog has easier veins and arteries to note as well.
Next week, we will move on into the mammalian organs of the brain, heart, kidney and an eyeball. This is a great way to talk about our own anatomy and learn about some of the things that help keep us alive.