Must see programming on PBS...
"For many decades, humans have harvested the horseshoe crab for use as fishing bait. Since the 1970s, we have even used horseshoe crab blood for medical purposes. But now we may have gone too far. Horseshoe crab numbers have declined significantly in the past few years. And, naturally, so have their egg numbers. This is especially important to a small shorebird that is a global traveler of the most impressive kind. The red knot makes one of the longest migrations of any animal -- a journey that takes it from one end of the earth to the other. To accomplish this feat, it relies on the eggs of the horseshoe crab. Without these eggs, the red knot is in danger."
Link: More at Nature/PBS.org
Red Knot image © 2008 Tom Prestby