Editing Turtle (section)

=== Eggs and hatchlings===
[[File:Snapping turtle 4 md.jpg|thumb|A female [[common snapping turtle]] depositing her eggs in a hole she dug|alt=Land turtle laying an egg in a hole|left]]

Turtles, including sea turtles, lay their eggs on land, although some lay eggs near water that rises and falls in level, submerging the eggs. While most species build nests and lay eggs where they forage, some travel miles. The [[common snapping turtle]] walks {{convert|5|km|mi|0|abbr=on}} on land, while sea turtles travel even further; the leatherback swims some {{convert|12000|km|mi|abbr=on}} to its nesting beaches.<ref name=Firefly/>{{sfn|Franklin|2011|p=33}} Most turtles create a nest for their eggs. Females usually dig a flask-like chamber in the substrate. Other species lay their eggs in vegetation or crevices.{{sfn|Orenstein|2012|p=277}} Females choose nesting locations based on environmental factors such as temperature and humidity, which are important for developing embryos.{{sfn|Franklin|2011|p=33}} Depending on the species, the number of eggs laid varies from one to over 100. Larger females can lay eggs that are greater in number or bigger in size. Compared to freshwater turtles, tortoises deposit fewer but larger eggs. Females can lay multiple clutches throughout a season, particularly in species that experience unpredictable [[monsoon]]s.{{sfn|Orenstein|2012|pp=273, 276}}
[[File:Tortoise-Hatchling.jpg|thumb|[[Marginated tortoise]] emerges from its egg|alt=Tortoise hatching from egg]]
Most mother turtles do no more in the way of parental care than covering their eggs and immediately leaving, though some species guard their nests for days or weeks.{{sfn|Franklin|2011|p=37}} Eggs vary between rounded, oval, elongated, and between hard- and soft-shelled.{{sfn|Orenstein|2012|p=274}} Most species have their [[temperature-dependent sex determination|sex determined by temperature]]. In some species, higher temperatures produce females and lower ones produce males, while in others, milder temperatures produce males and both hot and cold extremes produce females.<ref name=Firefly/> There is experimental evidence that the embryos of ''[[Mauremys reevesii]]'' can move around inside their eggs to select the best temperature for development, thus influencing their sexual destiny.<ref name="YeMa2019">{{cite journal |last1=Ye |first1=Yin-Zi |last2=Ma |first2=Liang |last3=Sun |first3=Bao-Jun |last4=Li |first4=Teng |last5=Wang |first5=Yang |last6=Shine |first6=Richard |last7=Du |first7=Wei-Guo |title=The Embryos of Turtles can Influence their own Sexual Destinies |journal=Current Biology |volume=29 |issue=16 |year=2019 |pages=2597–2603.e4 |issn=0960-9822 |doi=10.1016/j.cub.2019.06.038 |pmid=31378606 |doi-access=free |bibcode=2019CBio...29E2597Y }}</ref> In other species, sex is [[Sex-determination system#Chromosomal systems|determined genetically]]. The length of incubation for turtle eggs varies from two to three months for temperate species, and four months to over a year for tropical species.<ref name=Firefly/> Species that live in warm temperate climates can [[embryonic diapause|delay their development]].{{sfn|Orenstein|2012|p=286}}

Hatching young turtles break out of the shell using an [[egg tooth]], a sharp projection that exists temporarily on their upper beak.<ref name=Firefly/>{{sfn|Orenstein|2012|p=294}} Hatchlings dig themselves out of the nest and find safety in vegetation or water. Some species stay in the nest for longer, be it for overwintering or to wait for the rain to loosen the soil for them to dig out.<ref name=Firefly/> Young turtles are highly vulnerable to predators, both in the egg and as hatchlings. Mortality is high during this period but significantly decreases when they reach adulthood. Most species grow quickly during their early years and slow down when they mature.{{sfn|Orenstein|2012|pp=301–302}}