Data contain abundance (number of individuals per species) and biomass (wet weight or dry weight per species) information.

We assembled occurrence records (presence-only) for all four horseshoe crab species in Asia and Eastern America from our own observations, collaborators, scientific networks as well as through publishing a scratchpad site at http://horseshoecrabs.myspecies.info/. For many species, numerous distribution records exist in the literature, and we manually geo-referenced additional occurrence data from these sources.