The species that are unable to withdraw their legs cannot do so because the shell is too small. Turtles have a well-developed sense of sight and of touch. Scientific experiments indicate that they also have a good sense of smell, at least for nearby objects. A turtle can hear low-pitched sounds about as well as a human being can. The Life of A Turtle Young.
Turtles hatch from eggs, which are fertilized within the female's body.
One mating can result in the fertilization of all the eggs of a female for several years. Most species lay their eggs between late spring and late autumn, and some lay eggs more than once during this period. All turtles, including sea and freshwater species, lay their eggs on land. Among most species, the female digs a hole in the ground with her back feet when ready to lay her eggs. She lays the eggs in the hole and covers them with soil, sand, or rotting plant matter.