Why You Should Care About the Horseshoe Crab

Photo: NOAA

related articles

The horseshoe crab is an ancient, ugly and misnamed creature, and it is surprisingly important to the survival of migrating shorebirds and, well, us.

The New Jersey Marine Fisheries Council, according to the Philadelphia Inquirer just lifted a moratorium on harvesting horseshoe crabs in Delaware Bay, where the world's largest population of horseshoe crab lives. That means fishermen could begin grabbing horseshoe crabs by the tens of thousands so they can bait hooks and catch fish for Asian markets.

The issue at hand, that brought on the moratorium, is environmentalists' concern about the red knot, a migratory bird that relies on a feast of horseshoe crab eggs each May to make its long-distance flight from South America to the Arctic. As horseshoe crabs have declined, they've produced fewer eggs, which has left the birds too thin and weak to make the flight. Red knots could go extinct in just two years without help, according to the most dire estimate.

Having evolved 500 million years ago (give or take a few million years), the horseshoe crab is more closely related to spiders than to crabs. It is a highly successful creature, when measured against most living beings today, having survived every mass extinction to rock the planet's wildlife. (Today, being Darwin Day, is a good day to consider the process that gave us the horseshoe crab.)

During its long history, other creatures have evolved in concert. The red knot is the most notable example. But evolution also plays a role in the horseshoe crab's relationship to humans. The unique way its immune system works has allowed humans to exploit compounds in horseshoe crab blood in order to prevent the contamination of pharmaceutical products. The horseshoe crab's "primitive" eye has also yielded important scientific understanding of the way the human eye works.

Incidentally, the usefulness of the horseshoe crab amounts to one of the most pragmatic arguments for the preservation of biodiversity, and the importance of preventing extinctions. What useful compounds might be derived from the red knot, for instance? We won't know if the demise of the horseshoe crab rushes the species to extinction.

The Inquirer quoted one Virginia seafood processor saying that a moratorium on horseshoe crab harvesting "remarkably unimaginative." Given the long history, ecological uniqueness and surprising usefulness of the horseshoe crab, one could argue that slaughtering them for bait is the unimaginative idea.

COMMENTS ()