Green sea turtle: Difference between revisions - Wikipedia

Line 185:

Sea turtles return to the beaches on which they were born to lay their own eggs. The reason for returning to native beaches may be that it guarantees the turtles an environment that has the necessary components for their nesting to be successful. These include a sandy beach, easy access for the hatchlings to get to the ocean, the right incubation temperatures, and low probability of predators that may feed on their eggs. Over time these turtles have evolved these tendencies to return to an area that has provided reproductive success for many generations. Their ability to return to their birthplace is known as [[natal homing]].<ref name="Wynekey, J. 2013. Pp 59-70">Wynekey, J.; Lohmann, J.K.; Musick, J.A. 2013. The biology of sea turtles. CRC Press. Vol 3. Pp 59–70</ref> The males also return to their birthplaces in order to mate. These males that return to their homes know they will be able to find mates because the females born there also return to breed. By doing this, the green sea turtles are able to improve their reproductive success and is why they are willing to expend the energy to travel thousands of miles across the ocean in order to reproduce.

Mating behaviour is similar to other marine turtles. Female turtles control the process. A few populations practice [[Polyandry in animals|polyandry]], although this does not seem to benefit hatchlings.<ref name="Lee2004">{{cite journal |last =Lee |first =Patricia L. M. |author-link =Patricia L. M. Lee |author2=[[Graeme Hays|Graeme C. Hays]] |title =Polyandry in a marine turtle: Females make the best of a bad job |journal =Proceedings of the National Academy of Sciences |volume =101 |issue =17 |pages =6530–6535 |date =April 27, 2004 |doi =10.1073/pnas.0307982101|pmid =15096623 |pmc =404079|bibcode =2004PNAS..101.6530L |doi-access =free }}</ref> After mating in the water, the female moves above the beach's high tide line, where she digs a hole {{convert|11|–|22|in|cm|order=flip}} in depth with her hind flippers and deposits her eggs. The hole is then covered up again.<ref name=":6">{{Cite book|title=Turtles of the World|last=Bonin|first=Franck|publisher=The Johns Hopkins University Press Baltimore|year=2006|isbn=978-0-8018-8496-2|location=Baltimore, Maryland|url-access=registration|url=https://archive.org/details/turtlesofworld0000boni}}</ref> Clutch size ranges between 85 and 200, depending on the age of the female. This process takes about an hour to an hour and a half. After the nest is completely covered, she returns to the sea. The female will do this 3 to 5 times in one season.<ref name=":4" />

The eggs are round and white, and about {{convert|45|mm|abbr=on}} in diameter. The hatchlings remain buried for days until they all emerge together at night.<ref name=":6" /> The temperature of the nest [[temperature-dependent sex determination|determines the sex]] of the turtles at around the 20–40 day mark. Green Sea Turtles are type 1a, meaning males develop at cooler temperatures while females are produced under hot temperatures.<ref>{{cite journal |last1=Standora |first1=Edward A |last2=Spotila |first2=James R. |title="Temperature dependent sex determination in sea turtles" |journal=Copeia |date=1985 |pages=711–722}}</ref><ref>Spotila, J. R. (2004). Sea turtles: a complete guide to their biology, behavior, and conservation. Baltimore: Johns Hopkins University Press.</ref> At around 50 to 70 days,<ref>{{Cite web|title = Green turtle|url = http://wwf.panda.org/what_we_do/endangered_species/marine_turtles/green_turtle/|website = wwf.panda.org|access-date = 2015-10-19}}</ref> the eggs hatch during the night, and the hatchlings [[instinct]]ively head directly into the water. This is the most dangerous time in a turtle's life. As they walk, predators, such as [[gull]]s and [[crab]]s, feed on them. A significant percentage never make it to the ocean. Little is known of the initial life history of newly hatched sea turtles.<ref name="FWS"/> Juveniles spend three to five years in the open ocean before they settle as still-immature juveniles into their permanent shallow-water lifestyle.<ref name="Reich2007"/><ref name="LS20070918"/> It is speculated that they take twenty to fifty years to reach [[sexual maturity]]. Individuals live up to eighty years in the wild.<ref name="NGeo"/> It is estimated that only 1% of hatchlings reach sexual maturity.