Rays are among the largest fishes and evolved from sharklike ancestors nearly 200 million years ago. They share with sharks many life history traits: all species are carnivores or scavengers; all reproduce by internal fertilization; and all have similar morphological and anatomical characteristics, such as skeletons built of cartilage. Rays of the World is the first complete pictorial atlas of the world's ray fauna and includes information on many species only recently discovered by scientists while undertaking research for the book. It includes all 26 families and 633 valid named species of rays, but additional undescribed species exist for many groups.