Vertical Migration Activity Data from Larval American Horseshoe Crabs Raised in Different Environmental Conditions

These data are actograms showing vertical swimming activity of larval American horseshoe crabs (Limulus polyphemus). These animals were raised in different environmental conditions. One group were collected from the field as freshly-laid eggs (within 2 hours of being laid) and brought into the lab where they were raised in constant water conditions (22+/-1 psu salinity; 22C) and a 14:10 LD cycle until hatching. A second group was collected in the same way, but brought into the lab and kept in the same water and light conditions, but were kept in artificial tidal chambers where they were inundated for 2.4 hours, followed by a period of being kept out of water for 10 hours, simulating the cycles of tidal inundation that they would be exposed to in a nest in the wild. Another group of animals were collected as newly-hatched larvae in the nest. All of these animals were then placed into vertical migration chambers within 24-48 hours of hatching and kept in constant darkness and temperature (30C), where their vertical swimming activity could be monitored. Videos of vertical swimming were analyzed in Noldus EthoVision, and the data were converted into AWD files so that they could be displayed as actograms in ClockLab.