Horseshoe Crab Populations Declining Due to Climate Change - Softpedia

According to investigators, the sharp decline in crab levels can be associated with the climate change that has been taking place since the end of the last Ice Age.

Horseshoe crab - Limulus polyphemus - Information - ARKive

The horseshoe crab is a ‘living fossil’: forms almost identical to this species were present during the Triassic period 230 million years ago, and similar species were present in the Devonian, a staggering 400 million years ago.