One of my favorite critters is the Horseshoe Crab. We will most likely see them around this time of the year. The females come ashore in droves to spray their eggs, approximately 100,000 from each crab, into the edge of the surf. That equates to billions of very tiny eggs. They generally do this on a high tide and a full moon. The males follow along to fertilize the eggs.
If you go to the beach, most probably on one of the isolated islands that are accessible only by boat, you may very well see endless numbers of them buried in the sand near the high water mark. They have been stranded by the receding water. They bury their undersides in the wet sand to stay alive. The “high water” mark can be determined by the “wrack line” a line of debris and dead marsh grass left by the outgoing tide. You may see many deceased crabs and often just the shells, the latter being probably from previous seasons. We have them here but they become more prevalent in colder waters such as along the coast of Delaware and adjoining states.
The Horseshoe Crab is 445 million years old. They are unchanged in all that time.
They are perfect for the role they play in nature. I suspect a major factor in their longevity is their minimal contact with human beings. They are also non-aggressive and their diet, including marine detritus, small gastropods and muscles, essentially removes them from never ending food fights in nature.
Another factor is that other than a very small section at the base of the tail, there is nothing there for humans to eat.
Actually they are not a crab.
They are closer to the spider family. Their appearance is very misleading. The carapace, the shell, is sort of shaped like a horseshoe, thus the name. It has all sorts of spikes and points and is actually quite fragile.
There is a spiked tail that looks like a weapon of war. That along with the rather large crab like claws they possess, are a perfect example of why you should adhere to the old adage “Don’t judge a book by its cover”!
Horseshoe Crabs are totally harmless.
Horseshoe crabs contribute a lot to nature and to humanity. Their eggs are a vital source of nourishment for various other forms of marine life including sea turtles. They have ten major eyes and many more “sensors”.
Their eyes are a major source of information for scientists in their research for treatment of the human eye. The Horseshoe crab’s blood is copper based and blue. . It is estimated that a drop of extract from the blood of a horseshoe crab will detect microscopicamounts of bacteria in a swimming pool of water.
The extraction from the blood, called LAL is used extensively by manufacturers around the world in the purification of medical instruments or any medical equipment used in an invasive manner. A quart of the LAL is worth around $15,000 dollars on today’s market which is a $50 million dollar a year market. There is no harvesting of the crab in our waters. It is done around Delaware and places where the crabs are so plentiful they literally stack up several deep at egg laying time.
They cover beach areas like a blanket to the point where they are deemed a nuisance by beach dwellers. Hey! They were there first! By a few million years!
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The horseshoe crab happens to be a favorite food for the Whelk, a marine gastropod.
Whelks are abundant in the Delaware area also. Whelk fishermen were catching and chopping up the crabs to bait traps for catching whelks. They were measurably reducing the Horseshoe Crab counts and subsequently the egg count.
Today the whelk fishermen are paid to catch Horseshoes and carry them to a laboratory where a small amount of their blood is harvested. The crabs are tagged to prevent re-catching and released back to the water. A win-win for everyone, especially the crabs!
Enter the Red Knot! A little bird about the size of a Robin that every February lifts off from the tip of South America in a cloud of wings on a 20,000 mile round trip migration to the Arctic and back. The trip involves stretches of many days of nonstop flying over water. A tremendous amount of energy is needed for that amazing migration. Their main source of food, fatty Horseshoe Crab eggs.
The Red Knots always begin their migration at the time the horseshoe crabs start laying their eggs! Mother Nature knows best! When chopping up crabs to make bait for Whelks was in full swing there was a measurable reduction of the crabs and subsequently the eggs. There has been a resultant continuing drop in the number of Red Knots making the round trip from the tip of South America to the Artic and back. All too often, interruption of the natural flow of nature results in very undesirable collateral damage.
You can help! If you are walking the beach and see a stranded crab, buried in the sand and not moving, you can help by returning that critter to the sea. Just follow a few basic rules. 1. Dig away excess sand from around the carapace, (shell).
2. Lift the crab with fingers wrapped around each side of its shell. Don’t force it out of the sand. That can cause the shell to crack.
3. Never pick a crab up by its tail. It is fragile. It will break. The main function of the Horseshoe’s tail is to help it flip over when it is flipped on its back in the surf. A frequent happening. A broken tail is probably a death sentence.
The crab doesn’t know you are trying to help. You will feel the crab’s legs pushing away at your fingers trying to get free. There are seven pairs of legs. The claws are harmless. They have no bite strength.
Their pushing and the subsequent weird feeling on your fingers which can easily make you want to let go, are harmless. Just hang on.
4. Carry the crab, low to the sand in case you drop it. Sit it gently in the edge of the surf and it will very slowly crawl away without so much as a “thanks”! You may be contributing to the saving of countless yet to be born Horseshoe Crabs, helped to feed countless Red knots and will have contributed to the global sterilization of medical instruments by just helping one of these amazing creatures back into the water.
Hubbard is a local environmentalist, historian and activist. A former Green Beret, he’s a native of Savannah and lives in South Bryan.