Mollusks: From Snails to Squids

Your garden snail and a giant squid are actually cousins. They are both mollusks, soft-bodied weirdos

that all share a muscular foot and a mantle that usually makes a shell. Evolution took this

basic plan in wild directions. You have chitons clinging to rocks with eight armored

plates and clams that have no head and make pearls out of pure irritation. Then there are the

gastropods sliding around on land or sea. But cephalopods are the real showstoppers.

We are talking three hearts, blue blood, and jet propulsion. They used that same

squishy body plan to become the smartest invertebrates on the planet.