Page 603 - The British Big Four
P. 603
Eggs and Hatchlings - Danger is Everywhere
A pproximately a month after the last two or three at a time and the eggs are cov- components of the nesting habitat Lim-
mating, the female turtle emerges ered with mucus when they leave the cloa- pus, 1994). The average incubation of eggs
from the sea to lay her several clutches of ca. A few abnormally small or non-spherical ranges from 45 - 75 days, depending on the
eggs. The season and frequency of nesting eggs are usually found in each nest. temperature.
among female depends on individual pop-
ulations and the species of turtles. T Dhe eggs incubate in the sand and the uring incubation, or immediately fol-
hatchlings must dig their own way up lowing emergence from the nest, the
F emales lay their eggs high up on the
beach, usually within the vegetative from the nest after a successful incubation. hatchling is imprinted on to the earth’s
strand. Prior, the eggs contain a pinhead-
sized embryo that has developed to mid- Incubation period is an inverse function magnetic field at the rookery and possibly
gastrulation. Further development is
stopped a couple of days before the nester of nest temperature: higher temperatures also to the rookery’s olfactory characteris-
comes ashore to lay the eggs. The embryo
will not develop further until the eggs are result in shorter incubation period within tics. Responding to visual cues which guide
laid. While the eggs are deposited into the
egg chamber, they are tolerant to bouncing, embryonic tolerance limits. Lower tempera- it seaward as well as by orienting towards
rolling, tumbling or handling. However, two
hours after laying, the embryo will resume tures result in an increase in the incubation wave fronts, the hatchling is directed out
development and a simple roll of the egg
is enough to kill the developing embryo. period by retarding the rate of develop- into open water and away from the coast.
Marine turtle eggs resemble the shape and
color of table tennis balls. During oviposi- ment. Cool temperatures may cause some Sea turtle hatchling usually emerge from
tion, the eggs are usually dropped one, or
morphological and/or metabolic problems their nests at night, on early mornings or
depending on which stage of development after the rains, when the temperature is
they occur. Exposure to high temperatures relatively low. Nocturnal emergence is ad-
results in malformation of the embryo, es- vantageous to hatchlings in a number of
pecially in the first trimester. Incubation ways. First, there is lesser exposure to the
success is a function of the physico-chem- intense heat of day which can easily be fa-
ical (temperature, moisture content, salin- tal to them.
ity, gaseous exchange) and biotic (roots,
microbial flora, predators, nesting turtles)
