Essential Information & explanations, latest texts & monographs on
Amphibian.
The National Audubon Society Field Guide to North American Reptiles and Amphibians by NATIONAL AUDUBON SOCIETY
A Field Guide to Reptiles & Amphibians of Eastern & Central North America (Peterson Field Guide Series) by Roger Conant
The Salamander Room by Anne Mazer
What's It Like to Be a Fish? by Wendy Pfeffer
From Tadpole to Frog by Wendy Pfeffer
Frogs and Toads : An Owner's Guide to a Happy Healthy Pet by Steve Grenard
Frogs and Toads and Tadpoles, Too! (Rookie Read-About Science) by Allan Fowler
A Field Guide to Western Reptiles and Amphibians by Robert C. Stebbins
Koi: Living Jewels of the Orient by Steve Hickling
Fantastic Frogs (Hello Reader!, Level 2) by Fay Robinson
A Field Guide to Texas Snakes (Texas Monthly Field Guides) by Alan Tennant
Mouse Count by Ellen Stoll Walsh
Alligators & Crocodiles (World Life Library) by John L. Behler
Terrarium and Cage Construction and Care by Richard D. Bartlett
Turtles (All Aboard Science Reader) by Jodi Huelin
Amphibia(Redirected from Amphibian)
Amphibia
Scientific classification
Domain:Eukaryota
Kingdom:Animalia
Phylum:Chordata
Subphylum:Vertebrata
Infraphylum:Gnathostomata
Microphylum:Osteichthyes
Nanophylum:Sarcopterygii
Class:Amphibia
Orders
Urodela
Anura
Gymnophiona
The class Amphibia consists of all tetrapods (four-legged vertebrates) that do not have amniotic eggs. Amphibians generally spend part of their time on land, but they do not have the adaptations to an entirely terrestrial existence found in most other modern tetrapods (amniotes). There are about 3000 living species of amphibians.
Table of contents showTocToggle("show","hide")
1 History of amphibians
2 Classification
3 Reproduction
4 See also
5 External reference
History of amphibians
Amphibians developed with the characteristics of pharyngeal slits/gills, a dorsal nerve cord, a notochord, and a post-anal tail at different stages of their life. They have persisted since the dawn of tetrapods 390 million years ago in the Devonian period, when they were the first four-legged animals to develop lungs. During the following Carboniferous period they also developed the ability to walk on land to avoid aquatic competition and predation while allowing them to travel from water source to water source. As a group they maintained the status of the dominant animal for nearly 75 million years. Throughout their history they have ranged in size from the 15 foot long Devonian Ichthyostega, to the slightly smaller 6 foot long Eryops, and down to the tiny 1 centimeter long Psyllophryne didactyla, commonly known as the Brazilian Gold Frog. Amphibians have mastered almost every climate on earth from the hottest deserts to the frozen arctic, and have adapted to climatic change with ease.
- Solomon Berg Martin, Biology
- Duellman/Trueb, Biology of Amphibians
Classification
Traditionally the amphibians are taken to include all tetrapods that are not amniotes. Recent amphibians all belong to a single subgroup of these, called the Lissamphibia. Recently there has been a tendency to restrict the class Amphibia to the Lissamphibia, i.e. to exclude tetrapods that are not more closely related to modern forms than they are to modern reptiles, birds, and mammals.
There are two ancient, extinct, subclasses:
Of the remaining modern subclass Lissamphibia there are three orders:
Authorities disagree on whether Salientia is a Superorder that includes the order Anura, or whether Anura is a sub-order of the order Salientia. In effect Salientia includes all the Anura plus a single Triassic proto-frog species, Triadobatrachus massinoti. Practical considerations seem to favour using the former arrangement now.
Reproduction
For the purpose of reproduction all amphibians are bound to water. Several species have adapted to arid and semi-arid environments, but most of them need water to lay their eggs. The larvae breathe with exterior gills. After hatching they start to transform gradually to the adult's appearance. This process is called metamorphosis. Typically, the animals then leave the water and become terrestrial adults, but
there are some exceptions to this general way of reproduction.
The most obvious part of the amphibian metamorphosis is the formation of four legs in order to support the body on land. But there are several other changes:
- The gills are replaced by other respiratory organs, e.g. lungs.
- The skin changes and develops glands to avoid dehydration
- The eyes get eyelids and adapt to vision outside the water
- An eardrum is developed to lock the middle ear
See also
Decline in frog populations
Tetrapod
External reference
The above article is adapted from from Wikipedia All Wikipedia article text is available under the terms of the GNU Free Documentation License
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