Amphibians are vertebrates whose lives and evolutionary history connect aquatic and terrestrial environments. Their anatomy helps explain how vertebrates adapted to life on land, while their dependence on moist environments shows that this transition was not complete independence from water.
Amphibians are vertebrate tetrapods—vertebrates descended from four-limbed ancestors. The group includes frogs, salamanders, and caecilians. The name amphibian loosely translates as “dual life,” reflecting the aquatic and terrestrial phases found in many species, as well as the metamorphosis that many frogs and salamanders undergo.
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What does “amphibian” loosely mean, and what does it refer to?
It loosely means “dual life.” The name reflects aquatic and terrestrial phases in many amphibians’ lives and, in many frogs and salamanders, a metamorphosis between life stages.
What are the three respiratory surfaces used by amphibians?
Amphibians can exchange gases through their skin, lungs, and buccal cavity, the lining of the mouth.
How does buccal pumping move air into amphibian lungs?
Air enters the mouth through the nostrils. The nostrils close and the throat rises, forcing air into the lungs using positive pressure.
What is Tiktaalik, and why is it important?
Tiktaalik roseae was a shallow-water fish from about 375 million years ago with fish features and traits associated with early tetrapods, making it an important intermediate form in understanding the transition toward land.
What does pedicellate mean when describing amphibian teeth?
A pedicellate tooth has a calcified crown and root separated by a zone of noncalcified tissue.
Quiz questions
How do frogs generally reproduce?Answer: Eggs and sperm meet outside the female’s body, commonly in a moist environment.
What is lateral undulation in salamanders?Answer: Moving by bending the body from side to side while moving the limbs.
Which changes commonly occur as a frog tadpole undergoes metamorphosis?Answer: Gills and the tail disappear as limbs develop, and lungs and an eardrum form.
How can some live-bearing caecilians nourish their offspring?Answer: Females provide tissue from the oviduct before birth and skin after birth.
How did the spread of land plants contribute to declining atmospheric carbon dioxide during the Paleozoic?Answer: Plant roots helped break down rock, and carbon became stored in rocks.
Based on Biology 2e by Mary Ann Clark, Matthew Douglas, Jung Choi (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.