Frog Embryos Hatch Early to Escape Predator. In this amazing strategy for survival, frog embryos will hatch early to escape from an egg-eating snake by recognizing the vibrational cues of such attacks!
Research by Karen Warkentin at Boston University:
The hatching response to egg predators depends on physical disturbance of eggs...
Dangerous and benign disturbances overlap in both frequency and temporal pattern elements. However, they can be distinguished using a combination of features. Embryos use at least two temporal pattern elements, the duration and spacing of vibration events, as well as a frequency cue, the presence of frequencies within a certain low range, to assess risk. These components are all necessary for a vibrational cue to induce hatching. Additional features of vibrations appear to further modulate the escape hatching response.
http://people.bu.edu/kwarken/KWLabResearch2.html (Don't miss the video) - via Olgui