Page 371 - (DK) Ocean - The Definitive Visual Guide

REPTILES 369

Reproduction REPTILE CLASSIFICATION

True sea snakes are the only reptiles that reproduce at sea. They give
birth to live young (they are viviparous) after a gestation period of up to Three orders of living reptiles contain marine species. The fourth
11 months—much longer than most terrestrial species. All other marine order includes only the tuataras, which are terrestrial. Snakes make
reptiles, including sea kraits and marine turtles, lay their eggs on land. up the vast majority of marine reptiles. Others, such as wart snakes
Many of these animals breed on remote beaches and islands, and the and terrapins, live in fresh water, occasionally entering the sea.
adults sometimes arrive simultaneously and in large numbers. The eggs subfamily Hydrophiinae, spend their lives at
are incubated by ambient warmth, TURTLES AND TORTOISES sea, while sea kraits (members of the family
Order Chelonia
and in crocodiles and turtles, the Elapidae) breed on land. Seagoing lizards
nest temperature determines the About 300 species are all semiterrestrial; only one species, the
Seven turtle species are exclusively marine.
sex ratio of the hatchlings. Once Typical marine turtles (six species) have a marine iguana, gets all its food offshore.
the eggs have hatched, growth hard carapace. The separately classified
is fast, but mortality can be high. leatherback turtle has a rubbery carapace. CROCODILES AND ALLIGATORS
Order Crocodilia
Parental care is rare in marine
reptiles; female crocodiles are an SNAKES AND LIZARDS 23 species
Only the American crocodile and the
exception, guarding their nests Order Squamata saltwater crocodile live in both fresh
and carrying their young to water water and the sea. Crocodilians usually
7,400 species
after they have hatched. About 70 species of snakes live in salt feed at the surface, rarely diving more
water. True sea snakes, belonging to the than a few yards when at sea.
NEST IN THE SAND
After excavating a nest, a female
leatherback lays her eggs. Turtle
eggs are almost spherical, and
have soft, leathery shells, which
tear open when they hatch.

MARINE ADAPTATIONS
Thanks to their low metabolic
rate, marine reptiles can
remain underwater for long
periods. This young saltwater
crocodile is lurking on the
seabed off New Guinea. OCEAN LIFE