horseshoe crabs

Leave a comment June 6, 2013 Steve A. Wiggins

When possible, I like to follow up on events I mention on this blog. A few weeks back I mentioned the plight of the horseshoe crab and red knot, the bird species that feeds upon the crab eggs. Hurricane Sandy put the world’s largest nesting area for horseshoe crabs, compromised by human development, in serious danger. Ecological scientists, concerned for the fate of these intertwined species, frantically tried to rebuild eroded beaches so that the Christian crabs could sacrifice their children to the ravenous red knots. (Nature’s ebb and flow, it turns out, doesn’t always favor the unborn.) The good news is, that thanks-at least partially-to the efforts of the environmental engineers, crabs turned out en masse this year, and the red knots, on their transglobal migration, had plenty to eat. It is encouraging to hear that once in a while people impact their environment for good.

Perhaps unwittingly, a member of the American Littoral Society (which I am glad to learn does actually exist) was quoted in the New Jersey Star-Ledger as saying, “There was the potential for a catastrophe after Sandy.” I’m taking his words, intentionally, out of context because of their wisdom. Many people had, on the basis of human losses alone, already declared Hurricane Sandy a catastrophe. This simple quote is perhaps the most honest assessment of the universe it which we find ourselves. From the viewpoint of the not-human, Sandy was a catastrophe averted. The crabs, perhaps unconsciously, did what their biology programmed them to do. The birds feasted, and nature resumed its usual course. Humans weren’t in the center of this picture. We were supporting characters behind the scenes. There had been potential for catastrophe. Nature survived. Thrived, even.

Photo credit Carbon NYC, from WikiMedia

I do not in any way demean the material losses that many people suffered, and continue to suffer, because of the hurricane. Unlike us, however, horseshoe crabs have very limited options. They can’t fly to Las Vegas to propagate, legally or not. They can’t fell timber and build cabins in the woods. They can’t put up an igloo and survive Arctic winters. We the people have endless choices about where to settle. Every environment on the planet, except under water, we have explored, exploited, and populated. We are bound by the very statistics that we are told run this universe, to be in harm’s way once in a while. Human loss of life due to Sandy was not massive. We can rebuild. We do rebuild. The loss of horseshoe crab habitat could have spelled the end of two species of fellow inhabitants on this globe. Catastrophe was avoided. At least from the multiple eyes of the humble horseshoe crab.

1 Comment May 14, 2013 Steve A. Wiggins

445 million years may seem like a long time. For the horseshoe crab, however, the eons have been spans of years with little change from a rather simple existence that involves lurking under the water and crawling out this time of year to breed. For many of us, Hurricane Sandy is already a somewhat distant memory of days (weeks for some) of no electricity, sitting in the dark, wondering when life would get back to normal. Some parts of the Jersey shore are still suffering from the after-effects, but many of us have had to “just get on with it,” and forget about the damage caused. For the horseshoe crab, however, it is not so easy. For creatures that have survived virtually unchanged for hundreds of millions of years, Sandy dealt a cruel blow. The largest concentration of hermit crabs in the world breeds in Delaware Bay, just down where New Jersey and Delaware nearly come together. Numbers had been declining in recent years as horseshoe crabs were used for bait by fishers, landing them on the “near threatened” scale of the countdown to extinction. Hurricane Sandy eroded the beaches where the crabs breed, and human detritus, left years earlier to protect expensive homes, now provided unsurpassable barriers for most of the crabs. Biologists are at work trying to rebuild the habitat in time.

Not only the time-honored horseshoe crab, but the American subspecies of the Red Knot, a migrating shorebird, has come under threat. The Red Knot, which stops in New Jersey to snack on horseshoe crab eggs on its way to the northern breeding grounds, has been declining in numbers. No crabs, no birds. While the troubles of two species may not seem like cause for concern, the fact that one of those species has been successful since millions of years before the first dinosaur even appeared should give us pause. Dinosaurs showed up some 200 million years after the horseshoe crab had been solidly established on the beaches of the pre-Triassic world. Nature would not be set to wipe out the crabs after a single hurricane, but human obstacles may do what nature would not—endanger a perfectly adapted species so that “valuable” real estate can be protected.

It is tragic when people lose what they’ve worked to attain. It is, however, shortsighted to think that we are the only important species on the planet. We have evolved in a system that includes all the other organisms on our world—our family tree goes beyond that cousin that always embarrasses us to the very crabs that crawl in the silty, brackish water of the Delaware Bay. We’ve all had an impact on each other. Even if you’ve never seen a horseshoe crab, just by reading this post they have come into your life in some way. When we start constructing our grand dreams for a fine life, it seems that we should take into account those who have been here long, long before us. Their requirements are modest, but their place in the cladistic tree of life is just as important as ours. Extinction is forever.