Green sea turtle - Wikipedia
Loggerhead sea turtles have large heads and blunt, powerful jaws. Date of Listing: Threatened, July 28, Reproduction: As with other sea turtles, females return to lay their eggs on or near the same beach where they hatched. Unlike other sea turtles, courtship and mating usually do not take place near the nesting. A captive colony of green sea turtles, Chelonia mydas, has been maintained and Observations of this breeding colony show that the mating and nesting Ascension Island, or were bought from have any direct relationship to the repro -. The green sea turtle (Chelonia mydas), also known as the green turtle, black (sea ) turtle or .. After mating in the water, the female moves above the beach's high tide line, where she digs a hole inches in . Hawaiians and this petroglyph shows its importance dating to possibly when the islands first became populated.
Decades of research, however, including observations at sea, have produced useful insights into daily activities and behaviors such as courtship, mating and nesting. Daily Activities Sea turtles are known to feed and rest off and on during a typical day.
File:Courtship of green turtles.jpg
During nesting season, research conducted in the southeast United States helped discovered that loggerheads follow regular patterns between the nesting beach itself and offshore reefs and other rocky structures. When it is not nesting season, sea turtles may migrate hundreds or even thousands of miles.
Sea turtles can sleep at the surface while in deep water or on the bottom wedged under rocks in nearshore waters. Many divers have seen green turtles sleeping under ledges in reefs and rocks. Hatchlings typically sleep floating on the surface, and they usually have their front flippers folded back over the top of their backs. This behavior may help keep genetic diversity high in the population.
Beach Selection Most females return faithfully to the same beach each time they are ready to nest. Not only do they appear on the same beach, they often emerge within a few hundred yards of where they last nested. Nesting Behavior Only the females nest, and it occurs most often at night.
Green sea turtle
Sometimes she will crawl out of the ocean, but for unknown reasons decide not to nest. Constructing the Nest The female turtle crawls to a dry part of the beach and begins to fling away loose sand with her flippers.
After the body pit is complete, she digs an egg cavity using her cupped rear flippers as shovels. The egg cavity is shaped roughly like a tear drop and is usually tilted slightly. Laying and Burying the Eggs When the turtle has finished digging the egg chamber, she begins to lay eggs.
» Information About Sea Turtles: General Behavior
Two or three eggs drop out at a time, with mucus being secreted throughout egg-laying. The average size of a clutch ranges from about 80 to eggs, depending on the species. Because the eggs are flexible, they do not break as they fall into the chamber.
This flexibility also allows both the female and the nest to hold more eggs. Nesting sea turtles appear to shed tears, but the turtle is just secreting salt that accumulates in her body. Many people believe that while laying her eggs a sea turtles goes into a trance from which she can not be disturbed. For this reason, it is important that sea turtles are never disturbed during nesting. Once all the eggs are in the chamber, the mother turtle uses her rear flippers to push sand over the top of the egg cavity.
Once a female has left her nest, she never returns to tend it. Incubation Incubation takes about 60 days, but since the temperature of the sand governs the speed at which the embryos develop, the hatching period can cover a broad range. Essentially, the hotter the sand surrounding the nest, the faster the embryos will develop. Cooler sand has a tendency to produce more males, with warmer sand producing a higher ratio of females. Female turtles are unlikely to receive many of the proposed direct benefits of multiple mating e.
The aims of this review are to discuss aspects of turtle biology relevant to field-based studies of sperm storage and reproduction; review the available literature on the genetic mating systems of turtles; consider hypotheses for the evolutionary benefits of multiple mating and sperm storage in this taxon; and highlight future research directions that might take advantage of the unique opportunities afforded by the reproductive biology of turtles.
This is not intended to be a comprehensive review of sperm storage and competition, but a focused treatment on the special features of turtles relevant to paternity analysis and mating system studies. For a more comprehensive treatment of sperm competition in reptiles, see Olsson and Madsen Reproductive Biology of Turtles Social Structure and Behavior Although turtles typically do not display pair bonds or family group affiliations, social organizations exist in some species.
For example, dominance hierarchies have been described in gopher tortoises Gopherus agassizii; McCrae et al. Home ranges may not be exclusively guarded, but males occupying overlapping areas often establish dominance through fights Galbraith et al. In wood turtles Clemmys insculptamale dominance hierarchies also exist, and male rank has been shown to affect reproductive success. Males who consistently win fights against other usually smaller males enjoy a higher dominance rank and greater access to extended copulations with females Kaufmann Based on DNA paternity data, high-ranking males were found to father a significantly greater number of offspring than those of lower rank Galbraith Movement and dispersal are other important behaviors that influence a species' mating system in a given population.
In some freshwater turtles, gender differences exist in dispersal tendencies or in total distance traveled per year Morreale et al.
In addition, the two sexes may differ in seasonal activity levels, with females more active in the nesting seasons of late spring or early summer in north temperate regionsand males more active in the fall Gibbons ; MacCulloch and Secoy ; Pearse These movements have been interpreted as corresponding to peaks in female nesting and male mate-searching activities, respectively MacCulloch and Secoy Marine turtles present an entirely different life history, with intervals of several years between breeding events, and long distances traveled between communal feeding and nesting grounds Kuchling ; Limpus et al.
Little is known about the behaviors of marine turtles at sea, but both male and female green turtles Chelonia mydas have been observed mating more than once over a several-day period, immediately prior to the nesting season Booth and Peters Such multiple mating raises questions about mate choice, sperm competition, and genetic paternity of the offspring.
Thus, as has also been found for some lizards Bull et al.