Frogs mate in a position called amplexus, with the smaller male clasping the female from behind in a ride that can last two days or more. As she lays eggs, he expels sperm to fertilize them.

First, eggs hatch into all sorts of creatures - insects, frogs, ducks and dinosaurs, with opportunities for lots of animal movements.

When Xenopus frog eggs are experimentally ruptured, their cytoplasm rearranges itself to form compartments similar to cells, according to a study published October 31 in Science. The researchers, led ...