Horseshoe crabs are vexing. We capture millions for their blood (useful for testing the purity of phama). There are alternatives, but biologist worry that the animals will suffer more if they become useless to humans.
Fun horseshoe crab fact: horseshoe crabs have like five different types of eyes. Even that tail is basically one big eye, covered in photoreceptive cells. Those fuckers are really good at crawling around in the mud.
That image caused me to do a double-take! I live on Nantucket island, and am well aware of the Nantucket Conservation Foundation, and I've NEVER heard of this program nor anyone finding a tagged horseshoe crab.