About Amphibians & Reptiles
Amphibians and reptiles made their first appearance on earth during the Carboniferous period. They have similarities and amphibians and reptiles are often confused with each other. Amphibians begin their life in the water, later becoming land dwelling animals and reptiles are land dwelling animals from the moment they hatch. All continents of the world, with the exception of Antarctica, have reptiles and/or amphibians.
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Facts
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Reptiles and amphibians are vertebrates and ectothermic. This means that they have backbones and are unable to produce their own body heat. Their temperatures vary according to their surroundings. Both hatch from eggs but amphibians go through a larva stage before they become adults and reptiles are born as fully functional miniature adults. During the larval stage, amphibians dwell in water and look very different from adults of the same species. At the end of the larval stage, amphibians go through metamorphosis. During the metamorphosis stage, amphibians change into adults and become land dwellers.
History
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Fish that breathed through two lungs and had lobe-like fins lived during the Carboniferous era (360-286 million years ago). Primitive amphibians evolved from these fish. The amphibians retained both lungs and the lobe-like fins became limbs that strengthened and specialized to enable the animal to walk. Modern amphibians retain the process of metamorphosis from the primitive amphibians. These amphibians were the first land-dwelling vertebrates to appear in history. During the same period, primitive reptiles appeared. Reptiles did not have a larval stage and were terrestrial from the moment they hatched.
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Geography
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Reptiles and amphibians inhabit every continent except Antarctica. The caecilian ranges from southern Mexico to Argentina and also central Africa and Southeast Asia. All continents except Antarctica have salamanders, lizards and/or snakes. Turtles and tortoises inhabit the temperate and tropical regions of all continents except Antarctica. Crocodilians range throughout the Americas and Asia, Australia and Africa.
Types
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The smallest reptile is part of the gecko family According to the San Diego Zoo, there are 5,500 species of amphibians and over 6,500 species of reptiles. Amphibians have three major groups: Salamanders (amphibians with tails), caecilians, and frogs and toads. Reptiles have four major groups: turtles and tortoises, lizards and snakes, crocodilians, and the tuatara. The tuatara is the only species left from an ancient group of reptiles that goes back to the dinosaurs. Caecilians are legless amphibians and resemble large worms or slick snakes. Crocodilians include alligators, crocodiles and caiman.
Size
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Salamanders are one of the groups of amphibians Amphibians range in size from Izecksohn's toad, which only weighs a few grams, to the Japanese giant salamander that can grow to six feet in length and weigh up to 140 pounds. Reptiles range in length from the dwarf gecko with a maximum length of ¾ inches to the reticulated python that grows to 33 feet. The heaviest reptile is the saltwater crocodile that can weigh up to 2,200 pounds.
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References
Resources
- Photo Credit Reptile image by Sader from Fotolia.com Gecko Lizard on Branch image by Billy Tait from Fotolia.com salamander image by Wojciech Gajda from Fotolia.com
