Figure 1.
Hatching processes of the control and the mother-removed egg mass.
After mucus excretion, the mother suspended her own egg mass with her proboscis and maintained the egg-guarding posture (A). Mothers slightly vibrated the egg masses maintaining the guarding posture; then fertile eggs started to hatch synchronously approximately 4 min later (B). The embryos, moving peristaltically, emerged gradually from their shells (C). Almost all embryos had emerged completely by 30 min later (D). Newly hatched nymphs gradually began to move on the mass of empty eggshells. Then they started to take up the mucus secretion and the trophic eggs on the mass (E). However, if the mothers were removed from the egg mass, then about half the number of embryos failed to hatch. The other half hatched asynchronously for 24 h (F–J). Arrows indicate mucus secretions on the egg mass (A, F). Arrowheads indicate nymphs that are still hatching or which remain in the eggshell (J).
Figure 2.
Occurrence pattern of maternal vibration.
Means + SD are shown for numbers of vibration/min from the start of vibration generated by seven mothers. Arrows indicate the beginning of synchronous hatching.
Figure 3.
Hatching pattern of embryos exposed to the different treatments.
Hatching patterns of the control group (solid line and diamonds, N = 8), mother-removed group (dotted line and squares, N = 7), intermittent artificial vibration group (dashed line and triangles, N = 7), and continuous artificial vibration group (dotted-dashed line and circles, N = 5). Means + SD are shown for the percentage of hatched eggs at 5 min intervals for the first 90 min, and for 24 h from the start of hatching.