Far below the ocean's surface / live tiny, restless creatures / called zooplankton. / They are the ocean's heart. The largest migration of animals on Earth happens every single night as billions upon billions of microscopic animals―zooplankton―paddle from the ocean’s depths to its surface. On their journey, they swim daunting distances through predator-infested waters in pursuit of a midnight feast. Zooplankton are so small, and they live so deep, that we may never see them―but the entire food web depends upon their survival. Venture into the ocean’s twilight zone with Jilanne Hoffmann’s lyrical, evocative prose and Khoa Le’s luminous illustrations of these tiny yet magnificent creatures. "This shimmering tale of interdependence and survival is STEM storytelling at its best."―starred, Kirkus Reviews How THE OCEAN'S HEART came to be: When I was writing A River of Dust, I discovered that NASA's CALIPSO satellite not only measured the North African dust that flies across the Atlantic, it also recorded the massive nightly migration of zooplankton in the ocean. First, I was astounded that a satellite could do this, but then as I learned more about these delicate, beautiful animals, and that they're in danger, I knew I had to share what I'd learned with kids. The marine biologist from the Monterey Bay Aquarium Research Institute (MBARI) who reviewed THE OCEAN'S HEART at every step, Dr. Steven Haddock, was extraordinarily helpful. He's taken blackwater photos of many of the creatures shown in the book (some that are so new to scientists, they have not yet been named). In fact, Khoa Le, the illustrator used MBARI photos and videos extensively to inform her art, since the action of the story is based in the Monterey Bay National Marine Sanctuary. Also, her luminous illustration used on both end papers is based on a satellite view of the bay, a perfect way to open and close the story. As readers watch this epic race to eat before being eaten, I hope they'll fall in love with these tiny, gloriously strange and wondrous creatures who are so essential to all life on Earth. Jilanne Hoffmann has been a zoo train engineer, a waitress, a "real" engineer, a fitness trainer, a tai chi instructor, a freelance writer for nonprofit organizations, and now enjoys writing stories for kids and adults. She has a BS in Engineering and an MFA in creative writing. Her picture book, A River of Dust, was an ALA Notable Children's Book, a Bank Street College Best Children's Book, a Junior Library Guild Gold Selection, and an SCBWI Crystal Kite Winner. She lives in San Francisco with her husband, son, and rescue dog named Wrigley. Khoa Le is a picture book author and illustrator from Vietnam. Alongside her love of reading, art, and music, she draws inspiration from her journeys, discovering the beauty of the world―particularly through her deep love for the ocean and all things connected to it. Accompanied by her beloved cats, Khoa finds peace in her small studio, and she also cherishes the tranquility of nature.