We recently discovered that A. callidryas can hatch as early as 3 days in response to a strong hypoxia cue, well before the onset of hatching responses to predator attacks and artificial mechanosensory cues at 4 days (Warkentin et al., 2017). This extends their plastic hatching period to more than half of the typical undisturbed embryonic period. We hypothesize that elements of the hatching mechanism change throughout this dynamic developmental period, whichcould affect hatching performance and potentially alter the value of hatching as an antipredatordefense. In addition, because the onset of hypoxiacued hatching precedes that of mechanosensory-cued hatching (Warkentin et al., 2017) we hypothesize that insufficient mechanosensory development at 3 days might impede hatching-competent embryos from responding to attacks.