Optional Activities
- Build a Trilobite: Use clay or play dough to sculpt a trilobite. Notice the segmented body, the head shield (cephalon), thorax, and tail.
- Trilobite Art Project with Soul Sparkles: This is a fun art project that also allows you to discuss the body parts of a trilobite.
- Dissect a Crawfish: Learn more about exoskeletons and invertebrate anatomy by preforming a dissection on a crawfish. A video is available here and there is also a guide with worksheets available here.
- Fossil Mold: Press modeling clay onto the bumpy surface of a leaf or shell. Peel it off, you’ve made a mold fossil impression, just like real fossils form in sediment.
- Ediacaran vs Cambrian Compare: Make a T-chart comparing Ediacaran life (soft bodies, simple, no predators, radial symmetry) with Cambrian life (shells, eyes, complex behavior, predators, bilateral symmetry). What changed? Why did the Cambrian Explosion happen so quickly after hundreds of millions of years of simpler life?
- Growth and the Exoskeleton Problem The real limitation of an exoskeleton is molting: arthropods have to shed their shell to grow, and during that window they are completely vulnerable. Have learners research the molting process in a modern arthropod (horseshoe crab, tarantula, or lobster work well) and document the stages, the risks, and how long the animal is vulnerable. Then compare: how does an internal skeleton solve the growth problem? Build a simple size comparison chart of the largest known arthropods vs. the largest known vertebrates and analyze what the data suggests about which body plan scales better.