VII. Reproduction.
A. Sexual maturity.
Researchers are still studying sexual maturity in sea turtles.
1. Estimates of sexual maturity in sea turtles vary not only among species, but also
among different populations of the same species. Maturity may range from as early as three
years in hawksbills; 12 to 30 years in loggerheads; to 20 to 50 years in green sea
turtles.
2. Sexual maturity often is related to carapace size. Studies have shown that
hawksbills reached sexual maturity at a carapace size of 60 to 95 cm (24-37 in.);
loggerheads reached maturity at a carapace size of 79 cm (31 in.); and green sea turtles
reached maturity at 69 to 79 cm (27-31 in.).
3. Evidence suggests that some turtles continue to grow after reaching sexual maturity,
while some stop growing after reaching maturity.
Mating activity.
1. For most species, courtship activity usually occurs several weeks before the nesting
season.
2. Two or more males may court a single female.
3. Males have enlarged claws on their front flippers. These aid males in grasping the
shells of the females during mating.
4. Fertilization is internal. Copulation takes place in the water, just offshore.
C. Nesting behavior.
1. Like other turtles, sea turtles lay eggs. They must come ashore to do so.
2. Females nest a few weeks after mathing.
3. Depending on the species, sea turtle nesting follows a set pattern.
a. Females usually nest during the warmest months of the year. The exception is the
leatherback turtle, which nests in fall and winter.
b. Most females return to the same nesting beach each year. Recent studies suggest that
some females of some species will visit more than one nesting beach in a season.
c. Females of most species usually come ashore at night, alone, most often during high
tide. A female sea turtle crawls above the high tide line and, using her front flippers,
digs out a "body pit." Then using her hind flippers, she digs an egg cavity. The
depth of the cavity is determined by the length of the stretched hind flipper.
d. Depending on the species, the female deposits 50 to 200 Ping Pong ball-shaped eggs
into the egg cavity. The eggs are soft-shelled, and are papery to leathery in texture.
They do not break when they fall into the egg cavity. The eggs are surrounded by a thick,
clear mucus.
e. The female covers the nest with sand using her hind flippers. Burying the eggs
serves three purposes: it helps protect the eggs from surface predators; it helps keep the
soft, porous shells moist, thus protecting them from drying out; and it helps the eggs
maintain proper temperature. Experts can identify the species of turtle by the type of
mound left by the nesting female and by her flipper tracks in the sand.
f. Females may spend two or mroe hours out of the water during the entire nesting
process.
g. Females usually lay between one and nine clutches (groups) of eggs per
season.
h. It is possible that through the storage of sperm from one or several males in the
oviducts of the females, all clutches of the current nesting season may be fertilized
without repeated matings.
i. Females may nest every two to three years.
3. The Kemp's ridley and olive ridley form masses called arribadas (Spanish for
"arrival"). Arribadas contain thousands of egg-bearing females that come ashore
at the same time to lay eggs.
Hatching and Hatchlings
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