Earth Science: Biology – Animals – Reptiles
REPTILES date from 300 million years ago. when three evolutionary lines diverged: One became turtles and tortoises, another dinosaurs, lizards, snakes, crocodiles, and birds. The third became mammals
Reptiles include snakes, lizards, turtles, crocodiles, and the extinct dinosaurs. They have been able to successfully live on land because of several key adaptations.
Reptiles are well suited to life on land. Scales prevent their skin from drying out, their lungs are strong and efficient, and their eggs are encased in sturdy shells. Reptiles are cold-blooded, so they must regulate their body temperature by seeking shade or sunbathing.
They are efficient users of food and can survive in nutrient-poor regions such as deserts.
Lizards
Lizards are the largest and most diverse species group of reptiles. Most are very small. Typically, they bury or cover their eggs and hibernate during cold weather.
Except for the legless lizards (such as glass lizards), they have four legs and can be visually striking.
Turtles and tortoises
Turtles and tortoises have changed little in 150 million years of existence due to the protection offered by their shells. Most tortoises and freshwater turtles can withdraw their heads and legs into their shells, but sea turtles cannot.
All are omnivorous and lay their eggs on land. Most are threatened with extinction due to human encroachment and habitat destruction.
Crocodiles and alligators
The largest living reptiles are crocodiles and alligators. Limited to the warm regions of the world, they spend much of their lives in and around water.
They often float just below the surface, breathing though their vertical nostrils. When they spot a potential meal, they lunge and pull their victim under water.
Snakes
Snakes have a keen sense of smell and their ability to sense vibrations and temperature variations helps them to hunt effectively. Venomous snakes use a pair of hollow fangs to inject a paralyzing or deadly nerve venom into their prey.
Constrictors can unhinge their jaws in order to swallow a large prey.
BASICS
REPTILES date from 300 million years ago. when three evolutionary lines diverged: One became turtles and tortoises, another dinosaurs, lizards, snakes, crocodiles, and birds.
The third became mammals