*In a natural-world extravaganza, horseshoe crabs, birds and people meet up each spring on the shores of the Delaware Bay. This remarkable event is chronicled for younger readers and listeners with a simple two-level text and watercolor-and-pencil illustrations that correctly portray the various visitors: the crabs who’ve come ashore to lay their eggs; the red knots, sanderlings and ruddy turnstones stopping on their long migration north for the feast; and the scientists and vacationers who’ve come to marvel and record the annual event. Marks’ soft paintings bring young readers into the story by including a recognizable, possibly Asian-American, young girl as a focal character, one of the onlookers. Short simple paragraphs, each with a two-word headline, are set on top of the double-page spreads. The headlines summarize, spread by spread: “It’s starting. / They’re arriving. / They’re flapping. / They’re traveling. / They’re laying. / They’re landing. / IT’S HAPPENING!” And so forth. The narrative thus conveyed is simple and reliant on illustrations to understand antecedents, but it’s also accurate and informative. It’s followed by a more detailed explanation for older readers of the crab’s life cycle and behavior, its part in the food web, its importance to humans, especially in medicines and medical devices, and an extensive list of suggestions for further exploration. The endpapers show horseshoe-crab anatomy with labels that name and explain major parts. A splendid introduction to an extraordinary spectacle.