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 ...

Periwinkle, the Magellanic ... 3.6 million of these animals worldwide, making up between 1.1 million and 1.6 million pairs, which are necessary for reproduction. ...