Page 289 - French Polynesia
P. 289
Eggs and Hatchlings - Danger is Everywhere
A pproximately a month after the last dropped one, or two or three at a time and biotic (roots, microbial flora, predators,
mating, the female turtle emerges the eggs are covered with mucus when nesting turtles) components of the nesting
from the sea to lay her several clutches of they leave the cloaca. A few abnormally habitat Limpus, 1994). The average incu-
eggs. The season and frequency of nest- small or non-spherical eggs are usually bation of eggs ranges from 45 - 75 days,
ing among female depends on individual found in each nest. depending on the temperature.
populations and the species of turtles.
T he eggs incubate in the sand and the D uring incubation, or immediately
F emales lay their eggs high up on the hatchlings must dig their own way up following emergence from the nest,
beach, usually within the vegetative from the nest after a successful incubation. the hatchling is imprinted on to the earth’s
strand. Prior, the eggs contain a pinhead-
sized embryo that has developed to Incubation period is an inverse function magnetic field at the rookery and possibly
mid-gastrulation. Further development is
stopped a couple of days before the nester of nest temperature: higher temperatures also to the rookery’s olfactory character-
comes ashore to lay the eggs. The embryo
will not develop further until the eggs are result in shorter incubation period within istics. Responding to visual cues which
laid. While the eggs are deposited into the
egg chamber, they are tolerant to bounc- embryonic tolerance limits. Lower temper- guide it seaward as well as by orienting
ing, rolling, tumbling or handling. How-
ever, two hours after laying, the embryo atures result in an increase in the incuba- towards wave fronts, the hatchling is
will resume development and a simple roll
of the egg is enough to kill the develop- tion period by retarding the rate of de- directed out into open water and away
ing embryo. Marine turtle eggs resemble
the shape and color of table tennis balls. velopment. Cool temperatures may cause from the coast. Sea turtle hatchling usu-
During oviposition, the eggs are usually
some morphological and/or metabolic ally emerge from their nests at night, on
problems depending on which stage of early mornings or after the rains, when the
development they occur. Exposure to high temperature is relatively low. Nocturnal
temperatures results in malformation of emergence is advantageous to hatchlings
the embryo, especially in the first trimes- in a number of ways. First, there is lesser
ter. Incubation success is a function of the exposure to the intense heat of day which
physico-chemical (temperature, moisture can easily be fatal to them.
content, salinity, gaseous exchange) and
