Ammonites: the ups and downs

The new ELI published today is 'The ups and downs of ammonites; how did they adjust their position in the sea?

The demonstration shows how some animals which are buoyant in water can change their depth in the sea. Explain that ammonites had a coiled shell, but that the soft body only lived in part of the outermost coil. Inside the rest of the shell, the space was filled with gas, which made the animal buoyant.
Demonstrate this, using a boiling tube full of air with a bung to represent the shell of the ammonite. The air-filled tube represents the gas- filled inner coils of the ammonite. The bung represents the living parts of the animal, which can move towards the neck of the tube or retract back into it.
Many more activities about bringing fossils back to life can be found in the Evolution of Life category on our website.