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Inside The Classroom Bookshelf

High Tide for Horseshoe Crabs

Written by Lisa Kahn Schnell, Illustrated by Alan Marks
Published by Charlesbridge, 2015
ISBN 978-1-58089-604-7

Grades 2-8

Book Review 
Right now, we are in the midst of the annual spring migration. Birds that overwintered in Central and South America are returning to the northern edges of North America. This means that along the Atlantic flyway, it is also the annual horsehoe crab spawning. These prehistoric creatures are amongst our oldest species, having inhabited this earth for five hundred million years.  For the past 10,000 years or so, the horseshoe crab has played a critical role in the maintenance of bird populations on the East Coast of North America.  In May and June, horseshoe crabs all along the East Coast, and in particular, along Delaware Bay, crawl to shore to lay their eggs. As birds stop to rest along the route from the tropics to the arctic, they spend up to two weeks in the Delaware Bay, feeding and resting in order to complete their migration. Within that time period, each bird doubles its body weight, thanks to the thousands of horseshoe crab eggs it consumes. High Tide for Horseshoe Crabs illuminates this incredibly important event. It begins with the end pages, upon which diagrams of the horseshoe crab introduce the reader to the species. From there, it explores the spring spawning through chronological exposition. Alan Marks’s gorgeous watercolor illustrations zoom in and out on the crabs, eggs, birds, beaches, and people who witness the action. Within each illustration, from beginning to end, the reader watches alongside a young Asian girl and her mother or female caretaker, as well as the multigenerational cast of amateur and professional scientists, including bird enthusiasts and citizen scientists, who annually track the horseshoe crab population. Horeshoe crab populations are shrinking, and since they play a critical role in maintaining bird populations and, as the back matter informs us the pharmaceutical industry, scientists are trying to figure out why. High Tide for Horseshoe Crabs captures this endeavor and models the scientific process and the horseshoe crab life cycle through clear language, and the use of alliteration and vivid verbs (such as lunges, burrows, and zoom). Extensive back matter provides the reader with additional information about horseshoe crabs and the various threats to their numbers, and creates a pathway out of the book into other sources of information.  High Tide for Horseshoe Crabs is a bit like the horseshoe crab itself: a humble, hard-working book that packs a lot of important information between its pages.

Teaching Ideas and Invitations 

Grades 2-8

Young Voices: Horseshoe Crab and the Arts Contest. After reading the book and exploring some of the resources available in Further Explorations, have your students create horseshoe crab art. Students can write poetry, paint pictures, or write stories that involve the horseshoe crab. Have your students participate in the annual art contest,sponsored by the Ecological Research and Development Group.  Samples of past winners are available on the ERDG’s website as mentor texts for your students’ writing and art. This year’s entries are due by June 15, 2015.

Grades 2-5

Just the Headings. Read the book aloud, without showing the pictures, reading only the headings on each page. For example, to start, you would read over three two-page spreads the following: “It’s starting. They’re arrive. They’re flapping.” As students listen, have them jot down ideas about who “they” are and what “they” are doing. When you are done, have them share their thoughts in pairs or small groups. What do they anticipate the book is about, based on the title and hearing the headings? Next, reading the entire book aloud, and have students confirm their understandings.

Framing Content. In order to prepare students to absorb the information in High Tide for Horseshoe Crabs, have them first watch the four-minute 2011 video “Rendezvous with Horseshoe Crabs,” created by Public Media. This text can serve as a scaffold to the nonfiction book, and students can compare and contrast information in this Duet. Or, you might find that the reverse is true, and the picture book is the scaffold for the video. When students have read and viewed the two texts, have them pose questions about what more they want to know about the horseshoe crab. Use some of the resources below in Further Explorations to support their inquiry. Students can create a horseshoe crab podcast to inform other members of the school community about the ways in which birds are dependent upon crabs as part of their spring migration.

Grades 3-8

Comparing Scientific Content and Writer’s Craft. Read High Tide for Horseshoe Crabs and Horseshoe Crabs and Shorebirds in the Duet Model to explore scientific content and writer’s craft. Have students compare and contrast the information provided in each. What information about horseshoe crabs has changed in the twelve years since Horseshoe Crabs and Shorebirds was first published? How does each author structure her text? How do illustrations convey information in each? Finally, what literary elements does each author draw upon? How are sentences varied? What vivid verbs are used? Alliteration? How does each author effectively use similes and metaphors? How do these literary qualities collectively help readers understand the scientific information each text contains?

Watercolors and Science. Use this book as an entry point into the use of watercolor illustrations in nonfiction picture books. First, have students look at the watercolor illustrations in Horseshoe Crabs and Shorebirds, illustrated by Annie Cannon. Next, have students explore illustrator Alan Marks’ body of work in nonfiction illustration. Finally, have students look at selected watercolor paintings from John Jacob Audobon’s Birds of America. How do watercolors in particular capture the natural world? What can they reveal that other media may not? Have students research a scientific topic of their choice with relevance in your local community. Students can write information picture books or write the scripts for a video and use their watercolors as illustrations for the video.

Citizen Science. If you and your students are located on the Eastern Coast of the United States, participate in a Citizen Science project to protect the horseshoe crabs and the birds who depend on those crabs during their spring migration. Go to the Horseshoe Crab Survey webpage to find out how you can participate along the shores of Delaware and New Jersey. Or, if you live anywhere along the East Coast and you see a tagged horseshoe crab, you can share that information with the U.S. Fish and Wildlife Service.

Interrelationships: Horseshoe Crabs and the Food Web. This book focuses on the interrelationships between horseshoe crabs and the shorebirds that migrate north along the Atlantic Coast each spring. But what role do horseshoe crabs play in the lives of other animals? The “Helmeted Helpers” section of the back matter mentions eels, fish, sharks, and loggerhead turtles, as well as gulls, raccoons, and other animals that live along the shore. Have your students research the ways in which these other animals are dependent upon the horseshoe crab. Students may also want to explore some other books that focus on interdependence, featured in our entry on Welcome to the Neighborwood.

Grades 6-8

Critical Literacy 

Blue Blood and Shrinking Populations. At the end of the “Helmeted Helpers” section of the book, the author mentions the biomedical industry’s use of the blue blood of the horseshoe crab to create Limulus Amoebocyte Lysate (LAL). LAL is used to test medicines and medical devices for contamination. Human safety depends on this. Thus, horseshoe crabs are harvested in large numbers for their blood. The book also concludes by stating that “Although some scientists believe that North American horseshoe crab populaions are stable, not everyone is certain. In other parts of the world, horseshoe crabs are endangered.” How much is too much? What do your students think? What are the challenges the horseshoe crab population faces? Are they in trouble? If so, what is the cause? To what extent is biomedical use responsible? To what extent is overdevelopment of shorelines responsible? Have students research this topic further, using the range of resources included in Further Explorations. When their research is complete, students should write letters to federal, state, or local governments and/or pharmaceutical companies to share their findings. These letters may be purely informational, or they may be written to initiate further changes in practice.

Further Explorations 


Crenson, V. (2003). Horseshoe crabs and shorebirds: The story of a food web. Ill. by A. Cannon. New York: Marshall Cavendish.

Dunlap, J. (1999). Extraordinary horseshoe crabs. Minneapolis, MN: Carolrhoda.

Horowitz, R. (2000). Crab Moon. Ill. by K. Kiesler. Cambridge, MA: Candlewick.

Digital Resources 

Alan Marks Official Website

The Horseshoe Crab, The Ecological Research and Development Group

“Young Voices: Horseshoe Crab and the Arts Contest,” Ecological Research and Development Group Annual Horseshoe Crab Poetry, Writing, and Art Contest K-12

Delaware Shorebird Project, State of Delaware

Delaware Horsehoe Crab Spawning Survey, State of Delaware

Citizen Science, Horseshoe Crab, US Fish and Wildlife Service

Horseshoe Crab Annual Survey

Science on the SPOT: “Rendezvous with Horseshoe Crab,” Public Media

“Crash: A Tale of Two Species,” Nature Episode, PBS

“Why this Crab’s Blood Could Save your Life,” January 5, 2015, CNN

“The Blood Harvest,” February 26, 2014, The Atlantic

“A Bird Whose Life Depends on a Crab,” November 27, 2013, The New York Times

“Concerns Over Red Knots, Horseshoe Crabs, Oysters Spark Debates,” March 24, 2015, The Philadelphia Inquirer

Birds of America, John Jacob Audobon

Mary Ann Cappiello About Mary Ann Cappiello

Mary Ann is a professor of language and literacy at Lesley University. A former public school language arts and humanities teacher, she is a passionate advocate for and commentator on children’s books. Mary Ann is the co-author of Teaching with Text Sets (2013) and Teaching to Complexity (2015) and Text Sets in Action: Pathways Through Content Area Literacy (Stenhouse, 2021). She has been a guest on public radio and a consultant to public television. From 2015-2018, Mary Ann was a member of the National Council of Teachers of English's Orbis Pictus Award for Outstanding Nonfiction (K-8) Committee, serving two years as chair.


  1. Anonymous says

    Thank you for such a great review and extension activities! My students will love reading this book and learning about horseshoe crabs….clearly these creatures need more press!

  2. Alisha G. says

    Excellent post! Thank you for sharing this wealth of information.