Sea Turtle Facts: General Life
Cycle Of The Seven Species

These sea turtle facts are an average. If we took all the life cycles of all seven species and averaged them out, the result would be pretty close to what is described here.

Adult female sea turtles lay three or four clutches of eggs in a nesting season, and these are laid about two weeks apart from each other. Nesting occurs every third year.

Sea Turtle Facts: The Nest And The Eggs

On the night of laying, the female will inspect the beach slope from the water. If she is satisfied that it is safe enough and is clear enough of vegetation, she will make a nesting attempt. She will crawl up the beach slope to an area above the high tide mark. There she will go into a set of predetermined moves. First she will sweep the surface sand away with her front flippers, so that the loose dry sand does not interfere with the digging of the nest.

Once the damp sand is exposed, she will use her rear flippers as little shovels to dig a nest hole. The nest hole is approximately 50cm (23 inches) deep and is rounded out at the bottom to form the nest chamber, as shown to the right. She then lays about 100 eggs. Eggs are soft shelled and are the size of table tennis balls except for two species, the Leatherback and the Flatback. The eggs of these species are slightly larger than golf balls. These two species lay less eggs than the others.

Once the eggs are laid the female again uses her rear flippers to pack the damp sand loosely on top of the eggs until the nest hole is filled. She then does more sweeping and crawling, but this time with all 4 flippers. Here the aim is to hide the nest. Once the nest has been concealed the female makes her way back to the water. The whole process takes about two hours.

All nesting occurs in tropical or sub-tropical regions and in the dry season. This is because the heavy rains that come in the wet season would drown the eggs in the nest.

Sea Turtle Facts: Incubation And Hatching

Incubation takes 45 days and the sex of the hatchlings is determined by the temperature in the nest. The sex is decided about one third of the way through incubation, or after about 2 weeks. Hotter temperatures result in more female hatchlings, while cooler temperatures produce more males.

All hatchlings emerge from their eggs at the same time. They will not start digging their way out until the temperature of the sand above them begins to drop, indicating that night time has come. Then all the little turtles, called hatchlings, dig upwards together. As soon as they emerge from the nest, the hatchlings race towards the water.

Baby turtles head towards the water because it is the brightest object they can see. The star and moon light reflecting off the surface of the water make it lighter than the sand or the vegetated area behind the beach. It is the light the turtles move toward, which human developments can interfere with.

Sea Turtle Facts: Juveniles And Then Adults

Little is known about the juvenile stages of sea turtles, from the time they enter the water to when they return to breed as adults. Green turtle juveniles are often found on coral reefs, and Flatback young are thought to live in coastal areas such as mangrove thickets.

Turtles grow to adult size in 25 to 40 years. They then mate, with the female mating with several males prior to nesting. Females are believed to return to lay on the same beach they hatched from almost half a century before. This means that female turtles are split into relatively isolated populations. It is not known males have a preferred breeding location that is affected by their beach of birth.