Reptiles

Long before humans and other mammals appeared on the earth, reptiles were the dominant species. In fact, they were the first vertebrates (animals with backbones) to live entirely on land, having evolved from amphibian ancestors more than 250 million years ago.

Characteristics

What makes a reptile a reptile? There are several characteristics that all reptiles share:

  • Reptiles are ectothermic or "cold-blooded"

    The body temperature, and subsequently, the physical activities and physiological processes of reptiles depend heavily on conditions in the surrounding environment.

    To maintain a relatively balanced body temperature, reptiles must thermoregulate: they seek warmer areas when their surroundings are too cold, and colder areas when conditions are too warm.

  • Reptiles have dry, scaly skin

    The bodies of reptiles are covered with dry scales, or horny plates called scutes.

  • Reptiles have three possible means of reproducing their young

    Methods of reptile reproduction include:

    • Oviparity – laying eggs which develop and hatch outside the body
    • Ovoviviparity – retaining eggs inside the body until they hatch
    • Viviparity – developing an embryo inside the body and nourishing it by means of a primitive placenta until young are born live
    Unlike the eggs of their amphibian ancestors, the eggs of reptiles are adapted to survive on dry land. Reptile eggs have shells which keep the embryos within in a protected environment that is less prone to drying out.

Classification

Reptiles are grouped in a unique class of vertebrates called Reptilia. Within this class, reptiles are subclassified into four orders:

  • Order Crocodylia – includes alligators and crocodiles
  • Order Rhynchocephalia – includes a lizard-like animal called a tuatara found in New Zealand
  • Order Squamata – includes lizards and snakes
  • Order Testudines – includes turtles

The four orders of reptiles include 7500 living reptile species on earth. Nine species of two of these orders, Squamata and Testudines, can be found in the Province of Alberta.

Currently, one of Alberta’s reptile species, the prairie rattlesnake, is represented on this website. See:

 

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Updated: Oct 19, 2009