One of my personal favorite LIS animals, the horseshoe crab, is actually in quite a bit of trouble! Along with natural mortality, these animals are up against being used as bait in eel and conch fisheries, being used in the medical industry, pollution, and habitat degradation.
The ancestors of these animals date back to the Paleozoic era (540-248 million years ago). What a shame it would be if these animals ended up on the endangered species list now!! So much more research is needed on these creatures to truly understand their population levels and the extent of their population decline.
For more info, check out this awesome website by the Ecological Research & Development Group in Dover, DE.