Mike Tuke’s

Gastropods Columella 1 A P 5 min Students separate about 10 gastropods into those with and those without a columnella Columella 2 D Grind a Turretella down until the columella is exposed and show it to students Columella 3  D Some tourist shops sell slices of gastropod shells which can be placed on the overhead projector to show the columella. Evolute – involute  A P 5 min Students put a number of gastropods into a line with the most evolute one a one end and the most involute at the other end. Siphonal canal  A P 5 min Students must separate about 10 gastropods into those with entire apertures and those with siphonal canals. Apical angle A P 5 min Students put about ten gastropods in order of increasing apical angle and then measure the angle using a simple goniometer or a protractor. How many whorls A P 5 min Students are given a few gastropods and they must count the number of whorls on each. Plasticene coils  D or P 5 min A long, thin and tapering piece of plasticine is provided. This is coiled up to make an evolute gastropod. Students are then given a fatter and more carrot-like piece of plasticine to make an involute gastropod. Parameters controlling the shape D or P 10 min There is computer programme designed by Dr. D. M. Raup, which used to be available, which allowed one to vary the parameters and the computer would draw the gastropod shape.

Earth Science Activities and Demonstrations