Fig. 1From: Effects of copper and cadmium on development and superoxide dismutase levels in horseshoe crab (Limulus polyphemus) embryosMean date of hatching (±SE) of Stage 20 Limulus polyphemus embryos after a 4 h, b 8 h, c 16 h, and d 24 h acute exposure to Cu (filled bars) or Cd (open bars), followed by transfer to artificial seawater; n = 50 embryos per treatment. Control groups were raised in artificial seawater with no exposure to contaminantsBack to article page