Treading Lightly: Horseshoe Crabs

When you think of a horseshoe crab, you probably think of the large, brownish shell that looks something like a military helmet. If you flip one over, however, you'll immediately understand that horseshoe crabs are more closely related to spiders and scorpions than crabs. They look, quite frankly, like a giant spider sporting a WWI helmet---a design that hasn't changed over the last 400 million years. And these "sea spiders"  have ten legs for walking, swimming and eating.   As this Treading Lightly segment shows, the blood of these crabs---which is blue due to a lack of hemoglobin---is instrumental in determining whether pharmaceuticals are harboring bacteria.  As a result of this use as well as other environmental factors, horseshoe crab populations are declining around the world. The Taiwanese government began taking measures to support their "living fossil" populations this past month. And the Massachusetts Department of Fish and Game recently approved new rules protecting horseshoe crab populations on Cape Cod. The new rules, which go into effect April 16, include a body width standards for fishermen and a fishing ban for the five days surrounding each new and full moon, to protect spawning crabs.