Grades K-3. This nonfiction picture book balances information with literary language to provide an engaging choice for very young seashore scientists. Each watercolor-filled, double-page spread illustrates a moment in the life cycle of this arthropod: their nighttime arrival above the tide line to lay their eggs; the shore birds that prey on those eggs; beach walkers and environmentalists who tag individual horseshoe crabs to track migratory patterns and behavior; and the eventual departure of the hatchlings back into the ocean until the next season. Schnell weaves together the crabs’ behavior and that of other creatures on the beach, including humans, which gives a well-rounded and interesting view of the beach ecosystem. Marks’ watercolor-and-pencil illustrations depict a wide range of perspectives, both above and below the water, as well as a diverse cast of people and realistic renderings of horseshoe crabs. The fairly extensive back matter offers further information, including websites about different types of shore life, a map of the richest horseshoe crab mating areas in America, and activities and resources for expanded learning.