Dive deep to swim with the wild and wacky creatures without brains, hearts, or blood. The many jellyfish and jellies floating through the ocean are truly incredible. Some are tiny and deadly. Others are large and in charge. And some can even age backward! Learn what makes these creatures so unusual through exciting text, captivating photos, and highly repeatable fun facts. A back matter element features a scientist studying these unusual creatures. Are you ready for underwater oddities?