News Horseshoe Crabs Mate in Massive Beach "Orgy" Invertebrates

Beaches

Oceans

June 16, 2014 - Horseshoe crabs have been on Earth an estimated 450 million years, pre-dating the dinosaurs by some 200 million years. They are one of the few living creatures with blue blood, which is used by the pharmaceutical industry for testing drugs. Horseshoe crabs live in the ocean year-round, but they make one annual visit to the shoreline to lay eggs in sandy, wet beaches. In the United States, the highest concentration of egg laying is along the Delaware Bay.







Glenn Gauvry

Horseshoe Crab Conservationist



You're looking at a species that have managed to survive for a half a billion years. They've figured out how to harmonize with their environment in order to last that long.



This is actually an insane time for horseshoe crabs, people come from all over the world to see them, particularly in the Delaware Bay region where that's pretty much the epicenter of horseshoe crab spawning in the United States. But the concentration we have here is larger than any other place in the world.



They surveys that we do, they're done on the same night, they're done in the same way, year after year. We have a one meter quadrat square, putting it down every 20 meters, and we're counting the males and females that are within that quadrat.



Richard Weber

Horseshoe Crab Egg Researcher



They don't just rush up onto the beach, "Hey look, it's high tide," and lay a bunch of eggs. That doesn't pay off.



The females require sand that's lubricated with water to a certain degree, so that they can dig through it, and they also need it dry enough that they can create a cavity under themselves into which they release a batch of eggs.



Glenn Gauvry

Horseshoe Crab Conservationist



So she's going to lay about a cluster of eggs, that's maybe about the size of a golfball. There'll be about four or five thousand eggs in there. And then after she's laid those, you'll see her plow forward, go down a little bit, and do it again And she'll do it again, and she'll do it again, maybe four or five times in one tide, for about 20,000 eggs.



Richard Weber

Horseshoe Crab Egg Researcher



For every female that you'll see on the spawning tide, there are several males. She won't come ashore to spawn unless she has a male clipped onto her. But there are other males that are jostling around because by doing things right they can achieve some paternity during spawning. They sort of, game the system.



Glenn Gauvry

Horseshoe Crab Conservationist



The pharmaceutical biomedical community uses a test that's made from the blood of the horseshoe crab to determine whether there's any bacteria that would cause an infection, a fever, and cause us to die. Anything that's injected into our system, anything that comes in contact with our blood, that includes even the needle. Saline solution, spinal fluids like epidural, anything that comes in contact with those systems.



Richard Weber

Horseshoe Crab Egg Researcher



The blood of horseshoe crabs can be taken from the crab without causing 100% mortality. In fact, the mortality is about 30% of the bled crabs. Then those crabs who have been blood are released within 24 hours of capture.



Glenn Gauvry

Horseshoe Crab Conservationist



I feel this anticipation every year when the horseshoe crabs are starting to come to shore to spawn. We've got a lot of measure in place that are already starting to bear fruit from the declines we had back in the 90s, but we still have a ways to go before we feel the population is healthy and robust.



Every year when I'm seeing horseshoe crabs come up onto the beach I'm watching something that has played out for millions and millions and millions of years. And I'm just in awe.



