[capitan_refugio]

I thought the horseshoe crabs were more related to spiders, scorpions and the now-extinct eurypterids (thankfully extinct, because some species were like 15-foot upside-down swimming scorpions). Horseshoe crabs are in the order Xiphosurida, sort of all by themselves taxonomically. I seem to recall they had "blue blood" ... is that true?

[Don Joe]

I thought the horseshoe crabs were more related to spiders, scorpions and the now-extinct eurypterids (thankfully extinct, because some species were like 15-foot upside-down swimming scorpions). Horseshoe crabs are in the order Xiphosurida, sort of all by themselves taxonomically. I seem to recall they had "blue blood" ... is that true?

From the first link I grabbed via google query for "horseshoe crab" trilobite, "a Horseshoe crab is not a trilobite,but it is the closest living relative of the trilobite." (http://community-2.webtv.net/mrbbug2/doc2/)

(In the past, I've read in numerous places that they're related, so I just grabbed the first reference for this reply. As to the blood color, I've no idea. My mother never let me keep any of 'em I found at the beach when I was a kid. :)