Hidden beneath the waves, far from our familiar gardens and forests, the oceans of the world remain a realm of mystery. This unseen frontier is the cradle of life on our planet, home to creatures that originated over 600 million years ago and filled with a stunning array of spineless creatures: the invertebrates. As some of the oldest and most diverse organisms on earth, ocean invertebrates bend and break our rules of land-based biology. This book takes readers from the coral castles and underwater battles on reefs in St. Croix and Indonesia to the sparkling jellyfish light-shows off the coast of Hawaii to encounter underwater life in action.