Numerous tentacles, a funnel that evolved from the foot, a mantle that secretes the shell, and a pair of jaws with a radula- these all clearly show the nautilus’ mollusc design. Spiraling through the shell, a tube called the siphuncle removes the water in the chambers so the nautilus can maintain its buoyancy.
Mollusc Animation: Nautilus Body Plan
Next Generation Science Standards for this Video
Through natural selection, an ancient nautilus adapted new structures from the body plan it inherited from its molluscan ancestors, allowing it to survive off the bottom of the ocean.