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incubation sites produce males, cooler sites females. Crocodiles also lay their eggs in the ground beside water, but in the case of most species, the female also guards the site while they are incubating. She will also help the young crocodiles as they hatch, sometimes by dig- ging them out of the ground, and will guard them jealously from predators in the early stages of life in the water. Similar parental behavior can be seen in some species of fish, although the vast major- ity that live in shoals produce huge quanti- ties of eggs, and the young that hatch must

body of the mother—hence she appears to give birth to live young. Although consider- able effort on the part of the female reptile may go into selecting a suitable site for egg laying, with most species parental respon- sibility ends there. Such is the case with marine turtles, females of which haul them- selves ashore on remote beaches in order to lay their eggs in pits excavated in the sand. Once covered with sand, the female returns to the sea and has nothing more to do with the eggs. Intriguingly, however, her choice of egg laying site not only affects the survival of her offspring but also their sex: Warmer

Baby green turtles in the same nest all hatch at once, usually at night. They then dig a passageway to the surface of the sand and make their way down the beach to the sea.

With freedom in sight, a baby green turtle has to run the gauntlet of predators such as gulls on its way from its beach nest site to the open ocean.

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