It's Alive Life

These snails give live birth, and it’s the babies that may do the labor

Protecting eggs in mom’s body may have given periwinkle snails an advantage over egg-laying cousins

A photo full of rough periwinkle snails embryos. The snails within the embryos appear a beige color which stands out against the black background.

In rough periwinkle snails, embryos form and mature inside the brood pouch at different rates, as seen here. When it’s time to hatch, youngsters may have to crawl out of mom’s body and into the world on their own.

FREDRIK PLEIJEL

By Susan Milius

The oddball minority of animals that don’t lay eggs includes a tough little snail called a rough periwinkle.