As I See It

Bill Sargent, The Daily News of Newburyport, Edition May 3, 2019

“A 9-foot full moon high tide was creeping up Crane Beach on April 19. At noon, it seeped into the sand where a female horseshoe crab had been laying her eggs the night before.”

“The moisture was the signal she had been waiting for. She heaved herself out of the sand and lumbered down the beach to the lifesaving waters of the Atlantic.”

“A week later, Sandy Tilton videotaped another female horseshoe crab flipped over on her back on Plum Island’s Sandy Point. The crab had been vainly trying to use her tail to flip herself upright. In doing so, she had created a perfect circle in the sand and now she was exhausted.”

“Sandy flipped the female upright by carefully grasping her side rather than her tail, which seemed like such an obvious handle. For nature did not evolve horseshoe crab tails for human convenience but as a not particularly efficient way for the crabs to right themselves if a wave has flipped them over.”

“This crab had also come ashore on the high course tide to lay a bolus of 4,000 pin-sized green eggs. She would do this for two or three days on either side of the new and full moon high tides to lay as many as 80,000 eggs per season.”

“These were significant events on both sides of Plum Island Sound. But something was wrong. It was a perennial problem. Where was a male when you needed him?”

“If this were a healthy population, the female would have had to make her way through a stag line of lascivious male crabs eager to fertilize her eggs. If all went well, one male would grab her shell with specially modified clasper claws and hang on to her for several days while she was laying her eggs, but they would be surrounded by 30 or 40 other males crowding in to cover her eggs with creamy white milt.”

“But the sound’s population of horseshoe crabs is so small, there were no males available to fertilize her eggs. Hopefully, she would reabsorb the eggs and wait for the next full moon tide a month later.”

“There has never been a large population of horseshoe crabs in Plum Island Sound. In the 1960s, Carl Shuster drove from Maine to Florida doing a census of the population of horseshoe crabs in every major estuary. He found that horseshoe crabs are largest and most plentiful in Delaware Bay and they get smaller and less numerous as you go both north and south.” 

“But he also discovered that the smallest horseshoe crabs on the East Coast were in Plum Island Sound. This is because the sound’s waters are both cool and mixed with freshwater from the Merrimack and Parker rivers.”

“So, although these female crabs are between 10 and 20 years old, they are only the size of your outstretched hand. In Delaware Bay, a 20-year-old female would measure about 16 inches across and weigh 10 pounds.” 

“The Plum Island population is probably still recovering from the 1950s when the commonwealth paid fishermen bounties to kill horseshoe crabs in the belief they were shellfish predators.”

“But in the 1970s, scientists discovered that horseshoe crabs only eat worms’ detritus and Gemma gemma clams that look like immature quahogs – but are actually full-grown clams that never get larger than a quarter of an inch across.”

“Unfortunately, a few shell fishermen never got the memo and still stomp on horseshoe crabs whenever they see one, thinking they are killing a predator. But they are not.”

“They are killing an animal that has saved millions of human lives from gram-negative bacterial diseases that are as deadly as they sound. They are killing an animal whose processed blood is worth $30,000 a quart, an animal that is worth $6,000 if you keep it alive and use it to save human lives.” 

“So the next time you see a horseshoe crab on its back, be kind, flip it over and thank it for saving your life, because if you have ever had a flu shot or surgery, every scalpel, syringe, and vaccine was tested with processed horseshoe crab blood to protect you from fatal contamination.”

Copyright © 2019 The Daily News of Newburyport, Edition 5/3/2019

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“Crab Wars: A Tale of Horseshoe Crabs, Bioterrorism, and Human Health” by Bill Sargent is a great book for further information on Horseshoe Crabs.