Page 46 - Reptiles & Dinosaurs (Britannica Illustrated Science Library)

42 REPTILES: BACKGROUND REPTILES AND DINOSAURS 43

Reproduction

ost reptiles are oviparous. Some species Ovoviviparous
lay large numbers of eggs and then allow GREEN ANACONDA The eggs remain in the mother's body,
Eunectes murinus
M them to develop on their own, generally in An anaconda can have and hatching occurs there. The hatched
well-protected nests or hidden under dirt or sand. more than 50 offspring, young are diminutive versions of adult
which measure nearly
animals. Already independent, they do
Marine turtles, especially green turtles, travel to the coast 3 feet (1 m) long not receive any care from their parents.
to lay their eggs in the sand, where they are left at the at birth. 4
mercy of all who pass by. The females of other species,
however, fiercely protect their offspring, staying near their nests 145 to Exit
for long periods of time to scare away potential predators. It can take the baby
animal an entire day to
160 days exit, and it will have a
small sac hanging from its
navel. This is the sac of MOUTH
IS THE INCUBATION PERIOD yolk that provided it with is the first
part to
OF THE LEOPARD TORTOISE. food while it was appear.
Eggshells THE FEMALE incubating.
Reptile offspring develop within a REPRODUCTIVE Ovary Oviduct FOOT CARAPACE
(SHELL)
SYSTEM
liquid-filled sac called the amnion, has two ovaries that contain CARAPACE already has is already
which lies inside the egg. Most reptile the ovules, leading into two 2 3 Its growth mobility, thus completely
allowing the baby
eggs have soft, flexible shells, but some makes the reptile to walk. formed at
egg break.
birth.
have much harder shells. Through the oviducts that reach the cloaca.
shell, the hatchling absorbs the oxygen Fertilization occurs in the Fracture Hatching
forward part of the oviduct.
and moisture it needs for growth, while
its yolk provides it with food. The pressure exerted on The turtle is ready to
the shell from the come out and starts to
movements of the animal break the egg with its
Shell LEOPARD
Cloaca within such a cramped body. Hatching occurs. TORTOISE
1 Albumin space causes the shell to Geochelone
break from the inside.
pardalis
Oviparous Growth
The egg is buried by the mother, Habitat Africa
Reproduction that involves laying eggs in and the embryo begins to
which the offspring complete their Diet Herbivorous
development before hatching. Some species develop. The egg provides the Size 23-26 inches (60-65 cm)
lay large numbers of eggs and then allow necessary oxygen and food. Weight 77 pounds (35 kg)
them to develop on their own, generally in Cloaca
well-protected nests or hidden in dirt or
sand. In other species, such as crocodiles,
the females fiercely protect their offspring.
FER-DE-LANCE
Bothrops atrox
In one litter, it can produce up
to 80 offspring, each with a
length of 13 inches (34 cm).
LEOPARD TORTOISE
SHELL
allows oxygen to
enter, so the embryo
can breathe.
EMBRYO
Protected from drying
out, it can survive CONSISTENCY OF THE EGGS Viviparous
without water. The eggshell can be soft or hard.
Soft eggshells are usually found As is the case with most
in lizards and snakes, whereas
YOLK SAC mammals, the whole
surrounds the hard eggshells are common in embryonic developmental
embryo and stores turtles and crocodiles. cycle occurs inside the
food for its birth. mother's body, and the embryo
obtains food from close
contact with maternal tissues.
EGG TOOTH
ALLANTOIS A corneous, or horny,
Prolongation of spine on the beak for
the embryonic breaking the shell
intestines during hatching Hard Soft