Check Your Understanding
- What are some adaptations for living on land that are present in the amphibians?
- What features present in amphibians are also useful to reptiles for an aquatic lifestyle?
Introduction
While some types of reptiles, like snakes, alligators, and crocodiles, often have a bad repu-
tation due to their venom, as in snakes, or their aggressive behavior, as in all three groups,
reptiles are important both ecologically and economically, as we will see later in this lesson.
They also possess some unique traits and interesting behaviors, which we will also explore
in greater detail.
Reptiles are tetrapods andamniotes,whose embryos are surrounded by an amniotic mem-
brane. Modern reptiles inhabit every continent with the exception of Antarctica, and are
represented by four living orders: Squamata (lizards, snakes and amphisbaenids or “worm-
lizards”),Crocodilia(crocodiles,gharials(Figure13.19),caimans,andalligators)Testudines
(turtles and tortoises) and Sphenodontia (tuatara) (Figure13.20).
Figure 13.19: An Indian gharial crocodile. ( 3 )Traits of Reptiles
Reptiles are air-breathing, cold-blooded vertebrates that have skin covered in scales. The
majority of species areoviparous (egg-laying) although certain species of squamates are
capable of giving birth to live young. This is achieved, either by ovoviviparity (egg retention
within the female until birth), or viviparity (offspring born without use of calcified eggs).