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by Cindy Etgen
A full moon shines down on a group of educators huddled on a Delaware beach on a calm Friday evening in May. Toward the tide line, there is slow movement in and out of the waves. Moving closer, flashlights and headlamps expose a scene of wonder, one that many of the participants have never experienced. At their feet lie thousands of horseshoe crabs, brought out by the high tide, full moon and optimal beach environment.

The group is lead by Dr. Carl Shuster, the world’s leading authority on the Atlantic horseshoe crab (Limulus polyphemus). After a brief explanation of horseshoe crab anatomy, the group breaks into two, each carrying a clipboard and a 1-meter square grid to their start point. The teams move in opposite directions -- one north and one south -- and begin to count these amazing animals. Up and down the beach echo cries of amazement: “three females, 12 males”… “look at all of them, there are so many”…“my class is never going to believe this when I tell them!”

These excited participants -- teachers, naturalists, and environmental educators -- are all taking part in a unique weekend program called, Green Eggs and Sand (GE&S). Developed by a team from Maryland, Delaware and New Jersey, the Green Eggs and Sand – Horseshoe Crab/Shorebird Education Project explores the horseshoe crab and migratory shorebird connection, as well as the management implications of a species that plays an important role for so many. The intensive workshops take educators through the natural history of the crabs, their human uses, and finally, the investigations of managing a species that plays such an important ecological, economic and human health role.

Total Immersion
Saturday begins with a presentation from Dr. Shuster, a man who has studied horseshoe crabs for well over 50 years. He shares his experiences, including trips to Japan to learn about the other three species of horseshoe crabs, which are not found in the western hemisphere. These species have much smaller populations than the Atlantic species, which range from Maine to the Yucatan Peninsula. Dr. Shuster dives into a presentation that includes horseshoe crab biology, anatomy, spawning requirements and life cycle.

After the shorebird presentation, participants grab their lunches and head out for more field experiences. Excitement builds during the van ride and once at the designated site, the surveyors are divided into three groups, each led by an expert on that topic. First to head off to the beach are those looking for the shorebirds whose arrival coincides with the horseshoe crab spawning season.

From late April through June, thousands of horseshoe crabs make their way onto beaches up and down the East Coast. The largest population is found in the Mid-Atlantic region, specifically Delaware Bay. During high tides around the new and full moons, the crabs make their way onto beaches to spawn, leaving clutches containing thousands of small green eggs buried in the sand. The timing of spawning is imperative to migratory shorebirds such as the red knot that use the Delaware Bay as a refueling stop on their way from South America to their Arctic nesting grounds. As the beaches teem with hundreds of thousands of eggs from nests disturbed by wave action, these tiny birds feed to rebuild their body weight for the next leg of their journey.

The second group heads off with Dr. Shuster to learn more about how beach dynamics affect spawning and to search for those wonderful green eggs.

Group three drives to the dock where Frank “Thumper” Eicherly, Jr., keeps his boat. An integral part of the Green Eggs and Sand story, Thumper has worked with the team since the program’s inception. A conch fishermen, he relies on horseshoe crabs to bait his pots. Local watermen like Thumper play an important role in managing the crab population.

Thumper explains how critical horseshoe crabs are to his industry and explains how he developed a bait bag that uses much less crab than the old way of baiting pots. Instead of keeping his invention to himself, he chose to share the device, thereby reducing the amount of horseshoe crab used for bait and becoming part of the solution to reduce the amount of crabs harvested.

Later in the day, participants move into the next stage of the program: the human connections module. This module builds on the topic of horseshoe crab values, through activities that focus on their historical uses, the economics of the resource, and the fascinating connection between the crabs and human health. Participants are treated to a presentation on the biomedical industry, which bleeds horseshoe crabs and returns them alive to the waters from which they were taken.

The Importance of an Ancient Species
Horseshoe crabs are not true crabs but are more closely related to their close cousins, spiders and scorpions. Unlike true crabs, horseshoe crabs have book gills (a breathing organ containing folds of membrane like leaves of a book), chelicera (an anterior pair of appendages, often specialized as fangs) and five pairs of legs. A living relic from the age of the dinosaurs, the horseshoe crab has remained visibly unchanged over the last 360 million years.

Another interesting feature of horseshoe crabs is their blue blood, or hemolymph, which is copper-based (as opposed to human blood which is iron-based and turns red when it absorbs oxygen from the air). The crab’s blood cells contain a clotting factor that detects disease-causing bacteria. As a result, every injectable medicine and any device implanted into the human body are tested by a biomedical derivative of horseshoe crab blood.

Module four is what sets the Green Eggs and Sand curriculum apart from most other environmental education initiatives. Video clips tell the story of the coast-wide Horseshoe Crab Fishery Management Plan. Lesson plans and activities promote a better understanding of managing a multiple-use resource; illustrate varying views and issues of the stakeholders involved; explain why sound scientific data is so important to making good decisions; and shed light on how science, media and politics can be used and misused in the process.

At the end of the 3-day program, participants receive resources and contacts to help them begin the process of bringing the story to their students. Exhausted but excited to incorporate this new-found knowledge into their lesson plans, they finally head home.

The Green Eggs and Sand workshops provide educators with a wonderful base that can lead in many directions. Participants leave with the experience of face-to-face contact with experts in the field, a wealth of resources, and a better understanding of an amazing natural phenomenon.

One participant had this to say about the innovative program: “I had heard that it was great and it was… the quality and quantity of speakers and participants created a synergistic effect… the best workshop I have ever attended and I’ve been an educator for 35 years.

The GE&S team was honored to receive the 2004 Conservation Communicator of the Year Award, and earned first place in the 2005 Interpretive Media Awards in Curriculum Development from the National Association of Interpreters. Green Eggs and Sand team members include: Cindy Etgen, Maryland Department of Natural Resources; Gary Kreamer, Delaware Division of Fish and Wildlife; Katy O’Connell, Delaware National Estuarine Research Reserve; Sue Canale, New Jersey Division of Fish and Wildlife; and Mike Oates, ANEW, Inc.

For more information about Green Eggs and Sand workshops contact Cindy Etgen at

Cindy Etgen is DNR's Aquatic Resources Education Coordinator and is involved in environmental education on a state, regional and national level.  A graduate of Juniata College and the University of Maryland, she has been with DNR for 18 years.  Cindy sits on the Board of Directors for the Maryland Association for Environmental and Outdoor Education (MAEOE) and represents the Mid-Atlantic states on the National Project Wet Coordinator's Council.

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