Life History

Egg development in sea turtles

In response to a question posted on the Sea Turtle Rehab list server the following brief explanation of egg development was presented. Thank you Dr White for explaining the process so everyone can understand!

The process of egg development in sea turtles spans many months. Briefly: following a nesting period during which the female may have laid several nests, she probably migrates to a foraging ground elsewhere; that journey may take weeks or months depending on the distance. She may have eaten little during the entire nesting period and migration: living off her fat reserves. At her foraging ground she replenishes her body fat. Then she can start to develop the eggs for the next nesting period. She will produce all the egg follicles for however many nests she is going to lay (usually several hundred eggs): that process takes around 11 months and then egg development is suspended. When she has built up fat reserves she migrates and somewhere along the journey will mate. She stores all the sperm from the males. She will release the first batch of egg follicles and they get sperm, nutrients, membranes and shells ~ then egg development ceases again. She then proceeds to her nesting beach to lay the first clutch; after about 12 hours egg development proceeds. The female returns to sea (her internesting habitat) and, assuming she is laying more than one clutch, the next batch of eggs will develop in the same way. That typically takes 2-3 weeks depending on the individual female. The number of eggs per clutch varies: a rough mean is around 100 eggs (range say 45-190 eggs, but this differs by species and perhaps populations).  Often the final nest has fewer eggs, the last few remaining, but this is not always the case.

Dr Michael White 
Marine Zoologist - Tongareva Atoll Northern Cook Islands
Member of IUCN - Species Survival Commission: Marine Turtle Specialist Group