Editing Turtle (section)

== Reproduction and life cycle==
[[File:Tortoise Snap (2 frames).jpg|alt=Frames from a film showing one desert tortoise biting the other desert tortoise|thumb|Desert tortoises fighting]]
Turtles have a wide variety of mating behaviors but do not form [[Pair bond|pair-bonds]] or social groups.<ref name="Pearse 2001">{{cite journal |last=Pearse |first=Devon E.<!--Brigham Young--> |title=Turtle Mating Systems: Behavior, Sperm Storage, and Genetic Paternity |journal=Journal of Heredity |volume=92 |issue=2 |pages=206–211 |year=2001 |doi=10.1093/jhered/92.2.206 |pmid=11396580 |doi-access=free}}</ref> In terrestrial species, males are often larger than females and fighting between males establishes a [[dominance hierarchy]] for access to mates. For most semi-aquatic and bottom-walking aquatic species, combat occurs less often. Males of these species instead may use their size advantage to [[Sexual coercion among animals|mate forcibly]]. In fully aquatic species, males are often smaller than females and rely on [[courtship display]]s to gain mating access to females.<ref name="Berry 1980">{{cite journal |doi=10.1007/bf00572678 |pmid=28310555 |title=Sexual Size Dimorphism and Sexual Selection in Turtles (order Testudines) |journal=Oecologia |volume=44 |issue=2 |pages=185–191 |year=1980 |last1=Berry |first1=James F. |last2=Shine |first2=Richard |bibcode=1980Oecol..44..185B |s2cid=2456783}}</ref> In green sea turtles, females generally outnumber males.<ref name="Booth 1972">{{cite journal |doi=10.1016/S0003-3472(72)80155-6 |title=Behavioural Studies on the Green Turtle (''Chelonia mydas'') in the Sea |journal=Animal Behaviour |volume=20 |issue=4 |pages=808–812 |year=1972 |last1=Booth |first1=Julie |last2=Peters |first2=James A. }}</ref>

=== Courtship and mounting===

<!--need to lead in here, section is not about one species-->Courtship varies between species, and with habitat. It is often complex in aquatic species, both marine and freshwater, but simpler in the semi-aquatic mud turtles and snapping turtles. A male tortoise bobs his head, then subdues the female by biting and butting her before mounting.<ref name=Firefly/> The male [[scorpion mud turtle]] approaches the female from the rear, and often resorts to aggressive methods such as biting the female's tail or hind limbs, followed by a mounting.<ref name="Berry Iverson 2011">{{Cite journal |last1=Berry |first1=James |last2=Iverson |first2=John |date=December 2011 |title=''Kinosternon scorpioides'' (Linnaeus 1766) – Scorpion Mud Turtle |journal=Conservation Biology of Freshwater Turtles and Tortoises |pages=063.1–063.15 |doi=10.3854/crm.5.063.scorpioides.v1.2011 |url=http://www.iucn-tftsg.org/wp-content/uploads/file/Accounts/crm_5_063_scorpioides_v1_2011.pdf |access-date=August 20, 2019 |isbn=978-0-9653540-9-7 |doi-access=free |archive-date=February 4, 2019 |archive-url=https://web.archive.org/web/20190204032917/http://www.iucn-tftsg.org/wp-content/uploads/file/Accounts/crm_5_063_scorpioides_v1_2011.pdf |url-status=live }}</ref>

Female choice is important in some species, and female green sea turtles are not always receptive. As such, they have evolved behaviors to avoid the male's attempts at copulation, such as swimming away, confronting the male followed by biting or taking up a refusal position with her body vertical, her limbs widely outspread, and her plastron facing the male. If the water is too shallow for the refusal position, the females resort to beaching themselves, as the males do not follow them ashore.<ref name="Booth 1972"/>

[[File:Three-toed Box Turtle (47930139991).jpg|thumb|Mounting behavior in the [[three-toed box turtle]] |alt=Photograph of a male turtle mounting a female]]

All turtles fertilize internally; mounting and copulation can be difficult. In many species, males have a concave plastron that interlocks with the female's carapace. In species like the [[Russian tortoise]], the male has a lighter shell and longer legs. The high, rounded shape of box turtles are particular obstacles for mounting. The male [[eastern box turtle]] leans backward and hooks onto the back of the female's plastron.{{sfn|Orenstein|2012|pp=270–271}} Aquatic turtles mount in water,{{sfn|Orenstein|2012|p=270}}{{sfn|Franklin|2011|p=33}} and female sea turtles support the mounting male while swimming and diving.<ref>{{cite book |last1=Ripple |first1=J. |year=1996 |title=Sea Turtles |publisher=Voyageur Press |page=26 |isbn=978-0-89658-315-3}}</ref> During copulation, the male turtle aligns his tail with the female's so he can insert his penis into her cloaca.{{sfn|Franklin|2011|pp=20–22}} Some female turtles can [[Female sperm storage|store sperm]] from multiple males and their [[Clutch (eggs)|egg clutches]] can have multiple sires.{{sfn|Orenstein|2012|p=260}}<ref name="Pearse 2001"/>

=== 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}}

===Lifespan===
Turtles can live long lives. The oldest living turtle and land animal is said to be a [[Seychelles giant tortoise]] named [[Jonathan (tortoise)|Jonathan]], who turned 187 in 2019.<ref>{{cite web |url=https://www.guinnessworldrecords.com/news/2019/2/introducing-jonathan-the-worlds-oldest-animal-on-land-561882 |title=Introducing Jonathan, the World's Oldest Animal on Land at 187 Years Old |last=Millward |first=Adam |publisher=[[Guinness World Records]] |date=February 27, 2019 |access-date=July 14, 2020 |archive-date=August 9, 2020 |archive-url=https://web.archive.org/web/20200809153110/https://www.guinnessworldrecords.com/news/2019/2/introducing-jonathan-the-worlds-oldest-animal-on-land-561882 |url-status=live }}</ref> A [[Galápagos tortoise]] named [[Harriet (tortoise)|Harriet]] was collected by [[Charles Darwin]] in 1835; it died in 2006, having lived for at least 176 years. Most wild turtles do not reach that age. Turtles keep growing new scutes under the previous scutes every year, allowing researchers to estimate how long they have lived.{{sfn|Franklin|2011|pp=44–45}} They also [[negligible senescence|age slowly]].<ref name="oldage">{{cite journal |last1=Warner |first1=Daniel A. |last2=Miller |first2=David A. W. |last3=Bronikowski |first3=Anne M. |last4=Janzen |first4=Fredric J. |year=2016 |title=Decades of Field Data Reveal that Turtles Senesce in the Wild |journal=PNAS |volume=113 |issue=23 |pages=6502–6507 |doi=10.1073/pnas.1600035113 |pmid=27140634 |pmc=4988574 |bibcode=2016PNAS..113.6502W |doi-access=free }}</ref> The survival rate for adult turtles can reach 99% per year.<ref name=Firefly/>