REPRODUCTION

Reproductive cycles in sea turtles are repeated every two to three years depending on the size of the species (small species have shorter periods while larger species have longer periods). These periods, called remigration periods, are not permanent since turtles have the ability of stopping the cycle when environmental conditions are adverse.

Sea Turtles can lay 2-8 clutches of eggs in one single season.  The period of time between one clutch and another is called an internesting period. The number of clutches and the interesting period is particular to each species, although it can also be different between different populations of the same species. 

The mating rituals of sea turtles are different for each species, but there are generalized characteristics for all of them. Mating always occurs at sea after prolonged courtships (up to 72 hours in Chelonia mydas) in which the male bites the neck and forelimbs of females, and holds itself to the female by grasping her by the front flippers with the claws (1 or 2 depending on the species) of his own front flippers. Sexual activity is more intense during early hours of the morning. Females can also present a very active and aggressive behavior toward males if she is not interested in them in order to avoid mating.

Fecundation in sea turtles occurs inside the body. Males have a hemipenis, with a central longitudinal groove that adopts a tubular shape during mating that facilitates the intrusion of sperm into the female’s cloaca. The sperm is temporarily stored in grooves of the central section of the oviducts. When the female is ready to use the sperm, it introduces the sperm into the ovum (which occurs in the anterior part of the oviduct), and then the amniotic layers and shell are deposited to finish egg formation.

It’s believed that female turtles can store sperm in their bodies for extended periods of time, keeping their viability to fertilize eggs until the next reproductive season. The mechanism that regulates the amount of sperm needed for each clutch is unknown. Likewise, if fecundation precedes every clutch r if it occurs just at once for all eggs used in one season is unknown.