| Reptiles Introduction to the biology of snakes, turtles, lizards, alligators and crocodiles with a reptile quiz. |
| Reptiles Notes on cold-bloodedness, respiration, the skin, the egg, fertilization, the heart and the kidney of reptiles. |
| Reptiles Article discussing the advances reptiles have made over amphibians that have allowed them to move successfully into terrestrial habitats. |
| Reptilia_-_Biomedia_Zoology_Museum Notes on the evolution, body structure, classification and key features of reptiles. |
| Thermoregulatory_Associated_Skin_Color_Changes Researchers at the Tattersall Laboratory are investigating the relationship between skin color and the ambient temperature in a South American frog. |
| Americas_Center_on_Science_and_Society_(ACSS) At the City University of NY (CUNY). Conducts research and supports the integration of the natural and human sciences in public policy. |
| Colby_College Undergraduate program, course catalog, faculty list. |
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| George_Washington_University Center for International Science and Technology Policy. |
| Guide_to_Graduate_Education_in_Science,_Engineering_and_Public_Policy Advice for prospective students and links to university programs, from the American Association for the Advancement of Science. |
| Rob_Kling_Center_for_Social_Informatics A program in Social Informatics, focusing on the body of research and study that examines social aspects of computerization. Indiana University. |
| Nanoword_net Online nanotechnology resource focusing on education of the general public and distribution of nanotech products. Articles, definitions, and links. |
| Animal_Cells_and_Tissues__Organization_of_the_Animal_Body Notes by Michael J. Farabee on the structure and functions of each of the four major animal tissue types: epithelial, muscle, connective and bone. |
| Animal_Diversity Gives the key anatomical characteristics of members of Phylum Hemichordata, Phylum Chordata and its Subphyla Urochordata, Cephalochordata and Vertebrata. Illustrated by slides. |
| Animal_Organ_Systems_and_Homeostasis Homeostasis describes the physical and chemical parameters that an organism must maintain to allow proper functioning of its component cells, tissues and organs. |
| Auburn_University_-_Comparative_Anatomy Lecture notes on the digestive, circulatory, respiratory, urogenital and nervous systems in vertebrates, and also the muscles, limbs, skeleton and integument. |
| Chordata_-_Biomedia_Zoology_Museum An introduction to the taxonomy of the phylum Chordata with explanations of the technical terms used. |
| The_Evolution_of_Left-Right_Asymmetry_in_Chordates Article by Clive Boorman and Sebastian Shimeld discussing directional asymmetric morphology in which sidedness is fixed for a population, species or higher taxon. |
| Guide_to_Animal_Sounds_on_the_Net Provides an index to animal sounds on the Web including birds, mammals, reptiles, amphibians, fish and insects. |
| The_Integument Notes on the functions and anatomy of skin and its evolution. |
| The_Integument_and_its_Derivatives These notes cover the dermis and epidermis including skin, beaks, nails, hooves, horns, hair, feathers, scales and teeth. |
| Invertebrate_Members_of_the_Phylum_Chordata Outlines the differences between the subphylum Vertebrata and the two subphyla, Urochordata and Cephalochordata. |
| Online_Biology_Book__Glossary Comprehensive list of the technical terms you are likely to come across, with cross references. |
| Other_Animal_Sounds Doug Von Gausig has recorded the sounds made by various amphibians, reptiles and mammals, as well as birds. Here are the sound clips. |
| Respiratory_System Notes on external and internal respiration, ventilation, aquatic and aerial gas exchange in all classes of vertebrate. |
| The_Society_for_Experimental_Biology_(SEB) SEB membership is open to scientists world-wide and the Animal Section is a thriving community of enthusiastic scientists working across diverse scientific groups. |
| Urochordata_and_Cephalochordata Commonly called tunicates and lancelets, these marine creatures provide important clues in the study of vertebrates. |
| Urochordata_and_Cephalochordata Outlines the biology of the invertebrate members of the Chordata, the sea squirts, salps, Larvacea and Amphioxus. |
| The_Vertebrates Notes on the classification structure of the Vertebrates with a cladogram to review the evolutionary relationships of the craniata. |
| Faculty_of_1000 Database of published papers in biology, based on peer review. |
| The_Society_For_The_History_Of_Astronomy Academic and popular topics, with a focus on Britain. |
| Fluid_Ergativity_in_Gujarati Study by Peter Hook and Bharati Modi of ergativity (special way of subject marking in nominals) in Gujarati, with bibliography. |
| Gujarati_Language_Resources Brief listing of textbooks and online resources for students of the Indian language Gujarati. |
| Ratilal_Chandaria\'s_Gujarati_Language_Resources Includes online dictionaries and advice on installing and using Gujarati-compatible computer fonts. |
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| Topix__Geology News about geology, collected from various sources on the web. [RSS] |
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Amphibians and Reptiles: "Herps"
by Steve Price
Amphibians and reptiles share many characteristics. They both are ectotherms that rely on external heat sources to regulate internal body temperature. The first tetrapods were aquatic amphibians. They probably first used their legs to push along the bottom in ponds and streams. Some of these amphibians crawled out of their aquatic habitats and took up residence on land. Living amphibians and the reptiles evolved separately from 2 different extinct amphibian ancestors. The amphibians are divided into 3 subclasses: the extinct Lepospondyli; the extinct Labyrinthodontia, which are ancestral to the reptiles, mammals and birds; and the Lissamphibia or modern amphibians.
Possibly the most important difference between the amphibians and reptiles is water. Amphibians are tied to water for respiration and reproduction. Even salamanders and toads that have lungs gain as much as 35% of their oxygen by absorbing it through their skin (Withers, 1992). Reptiles were able to leave water completely only after evolving a relatively water-proof skin and an amniotic egg. A hard shell and membranes around the developing embryo limit water loss. Because of this reptiles are in some ways closely allied with birds and mammals.
The most characteristic shared trait between modern day amphibians and reptiles is ectothermy. Ectothermic animals are "cold-blooded" and must rely on an outside source of heat to regulate body temperature and activity levels. In order to remain physiologically active for long periods of time, animals must maintain a high core body temperatures. Ectotherms usually keep warm by muscle activity or by sunning.
The reason these 2 groups are studied together is mainly historical. As recently as 100 years ago amphibians were classified as a sub-group of reptiles and studied together as the field of herpetology. This historical classification has been preserved and herpetologists still study both amphibians and reptiles, but many specialize on one or the other. In fact herpetologists often refer to amphibians and reptiles singly as "herps" or sometimes even "herptiles".
Biodiversity
Topics: Introduction . Plants
. Animals
. Mammals . Birds
. Reptiles &
Amphibians . Arthropods
. Spiders
. Insects
© 2001-2004 The Cofrin Center
for Biodiversity and the University of Wisconsin Green Bay,
All Rights Reserved
Last
updated on
July 6, 2006
