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The horseshoe crab is one of our region’s great natural wonders. Every year in late springtime, nature lovers descend on the beaches of Delaware Bay to see the strange ancient sea creatures waddle up onto the beaches of Delaware Bay in a spectacular spawning ritual.

The animals didn’t always get that sort of respect from humankind. What you see up top here are horseshoe crab carcasses piled up in a scene from Bowers Beach, Del. in the 1920s. They are drying out in advance of a trip to a fertilizer-making factory.

This represents just one chapter in a long and often checkered history of human-horseshoe relations.

• Native Americans almost certainly harvested horseshoes for food. They also put the creatures to other uses. Early European visitors who wrote down their observations made mention of crab carapaces (or helmets) being used to bail out canoes. Others mentioned the way telsons (or tails) were used as spear tips.

• Native Americans were using dead horseshoe crabs as fertilizer on farm fields before Europeans arrived. Presumably, that’s where those European immigrants got the idea to do the same.

• This practice grew more and more popular as the 1800s progressed and the 1900s began because it turned out that the Indians were right–horseshoes made for a spectacular fertilizer. Here is one breathless report from 1908: “On land which would not grow wheat at all up to that time, crops of 20, 25, and even 30 bushels to the acre have been raised by the use of these crabs.”

• The fertilizer was known as “cancerine,” an old word that meant “derived from crabs.” This is actually dead wrong, of course. Despite their informal name and their resemblance to crustaceans, horseshoes aren’t crabs at all. The ancient creatures are more closely related to sea spiders and scorpions.

• Put that linguistic snafu aside. From the mid-1800s into the 20th century horseshoes were harvested in gigantic numbers and then stacked outside of factories to dry in the sun. Inside those factories, the dried horseshoe carcasses would quite literally get run through the grinder and eventually be processed into a fertilizer “meal.”

Horseshoe Crab Apocalypse Crabs at Dock• Local farmers also harvested horseshoe eggs from the beach, which they then fed to chickens.

• The numbers are astounding: “In 1856, more than a million crabs were taken from a one-mile stretch of New Jersey beach.” In the year 1880, more than “4 million crabs were harvested from Delaware Bay.”

• The U.S. human population was growing by leaps and bounds during these decades. As sad as it is to think of those dead horseshoes, we might also keep in mind that they helped many a farming family get by. They also helped provide many others with enough food to put on the table.

• But it all got out of hand. The horseshoe crab population went into decline by the late 1800s and showed signs of being in serious trouble by the 1930s. The crabs got lucky in the long run, however. Modern fertilizers came on the scene in the 1960s and took over the market soon thereafter. The last of the “cancerine” factories near Delaware Bay closed during the 1970s.

Horseshoe Crab Apocalypse Drying in Sun• Experts still watch horseshoe-population numbers carefully nowadays. Starting in the 1990s, the crabs became quite popular as bait in the eel and conch fisheries. Plus, the blood of horseshoe crabs has become an important and life-saving resource in modern medicine.

• I tell that scientific/medical miracle part of the story in a chapter in my book, “You Wouldn’t Believe: 44 Strange and Wondrous Delmarva Tales.” You can find that book–and my other ones–here.

• Much of the information in this post comes from a 2009 article by Gary Kreamer and Stewart Michels titled “History of Horseshoe Crab Harvest on Delaware Bay.” Find the full article here.

I wrote about the natural wonder of the horseshoe spawning ritual in this piece. If you haven’t gone to see it, you really should. It’s incredible.

The photo I used up top is in the collection of the Delaware Archives.

• posted by Jim Duffy for Secrets of the Eastern Shore/Whimbrel Creations LLC in April 2024. Thank you for spending time on this site!

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