<P> The female relies on her hind feet for digging . She may accumulate so much sand and mud on her feet that her mobility is reduced, making her vulnerable to predators . To lighten her labors, she lubricates the area with her bladder water . Once the nest is complete, the female deposits into the hole . The freshly laid eggs are white, elliptical, porous, and flexible . From start to finish, the female's work may take four hours . Sometimes she remains on land overnight afterwards, before returning to her home water . </P> <P> Females can lay five clutches per year, but two is a normal average after including the 30--50% of a population's females that do not produce any clutches in a given year . In some northern populations, no females lay more than one clutch per year . Bigger females tend to lay bigger eggs and more eggs per clutch . Clutch sizes of the subspecies vary, although the differences may reflect different environments, rather than different genetics . The two more northerly subspecies, western and midland, are larger and have more eggs per clutch--11.9 and 7.6, respectively--than the two more southerly subspecies, southern (4.2) and eastern (4.9). Within subspecies, also, the more northerly females lay larger clutches . </P> <P> Incubation lasts 72--80 days in the wild and for a similar period in artificial conditions . In August and September, the young turtle breaks out from its egg, using a special projection of its jaw called the egg tooth . Not all offspring leave the nest immediately, though . Hatchlings north of a line from Nebraska to northern Illinois to New Jersey typically arrange themselves symmetrically in the nest and overwinter to emerge the following spring . </P> <P> The hatchling's ability to survive winter in the nest has allowed the painted turtle to extend its range further north than any other American turtle . The painted turtle is genetically adapted to survive extended periods of subfreezing temperatures with blood that can remain supercooled and skin that resists penetration from ice crystals in the surrounding ground . The hardest freezes nevertheless kill many hatchlings . </P>

How long does it take for painted turtles to hatch