Ron Scheffel Day 85 of incubation Shortly before hatching: The egg starts changing its colour and now appears more greyish. This phenomenon is a result of the embryo moving inside the egg and detaching the amnion. Not all eggs will display this change, though, and some will remain white. Day 86 of incubation The egg now shows some dark grey spots, in particular in the place where the hatchling will later break through the shell and stick its head out. Day 87 of incubation The actual hatching process commences and may take up to a week to complete. The incubation period of Testudo kleinmanni eggs varies greatly, with the earliest hatching (without any remnants of a yolk sac) having been recorded by me on Day 80 in 2011, but you may also have to wait until Day 150. The eggshell has been cracked open on one of the poles. Day 88 of incubation The hatchling frees itself of the eggshell. The plastral fold of the hatchling is still very distinct right after emerging from the egg. Day 127 of incubation An egg that was opened after it failed to hatch and turned grey in colour: The embryo still has a large yolk sac attached and must have perished a while ago. Tab. 10. Photographic timeline of the development of fertile and infertile eggs. 36 RADIATA 23 (1), 2014
Testudo kleinmanni, the Egyptian Tortoise – small yet demanding I incubate the eggs in three different incubators under different temperature regimes: Incubator 1 (Fig. 66): Incubation of female offspring. Incubator 2: Incubation of male offspring. Incubator 3: Experimental incubation at temperatures that are slightly varied every year in a quest to identify the exact vertex value beyond which females will be produced and minimize the development of anomalies that are ascribable to incubation temperatures. Fig. 65. Hatchling. Fig. 66. View into one of the three incubators used. RADIATA 23 (1), 2014 37
