reptile
Definition
Reptiles are a class of vertebrates that are characterized by their scales, ectothermy, and amniotic eggs. Reptiles are the first vertebrates to lay amniotic eggs, which allowed them to live on land and in a wider range of habitats than amphibians.
There are four living orders of reptiles: Testudines (turtles), Crocodilia (crocodiles and alligators), Squamata (lizards and snakes), and Rhynchocephalia (tuatara). Reptiles are found on all continents except Antarctica, and they play an important role in many ecosystems.
Some of the key characteristics of reptiles include:
- Scales: Reptiles have scales that cover their body. Scales are made of keratin, the same material that makes up hair and nails in humans.
- Ectothermy: Reptiles are ectotherms, which means that they rely on external sources of heat to regulate their body temperature. This is in contrast to endotherms, such as mammals and birds, which can generate their own body heat.
- Amniotic eggs: Reptiles lay amniotic eggs. Amniotic eggs have a hard shell that protects the embryo from the environment. They also have a fluid-filled sac that surrounds the embryo and provides it with oxygen and nutrients.
Reptiles are an important part of the ecosystem. They play a role in controlling populations of other animals, and they are also a source of food for many other animals. Reptiles are also used in research, and they can be found in zoos and aquariums around the world.
How can the word be used?
The crocodile is a reptile that lives in both fresh and salt water.
Different forms of the word
Noun:
a cold-blooded vertebrate animal of a class (Reptilia) that includes snakes, lizards, turtles, and crocodiles.
Etymology
The word "reptile" comes from the Latin word "reptilis", which means "creeping".
The first recorded use of the word "reptile" in English was in the 16th century.
Question
What are the four living orders of reptiles?
AQA Science Exam Question and Answer
Question:
Describe the main characteristics that define reptiles as a group of animals, and explain how these features enable them to thrive in a range of environments. Provide an example of a reptile species and its adaptations.
Answer:
Reptiles are a class of cold-blooded vertebrates characterised by several key features. These include having scaly skin, breathing air with lungs, and laying amniotic eggs. These traits collectively enable reptiles to adapt to diverse environments. Their scaly skin helps reduce water loss, making them well-suited for arid climates. Unlike amphibians, reptiles do not rely on moist environments for survival.
An example of a reptile is the desert-dwelling Gila monster. This venomous lizard is adapted to its habitat in several ways. Its scaly skin prevents water loss, allowing it to thrive in the dry desert. Gila monsters have a specialised jaw joint that enables them to consume large prey and store fat for sustenance during periods of scarce food. Their venom is used to immobilise prey and aid in digestion.
Reptiles' ability to lay amniotic eggs, which have protective shells, further enhances their adaptability. This adaptation frees them from dependence on aquatic environments for reproduction, making them capable of colonizing diverse habitats, from deserts to rainforests.