BIO 200 Lecture Notes - Lecture 35: Poikilotherm, Homeothermy, Notochord

19 views7 pages

Document Summary

In this lecture we continue to identify where key characteristics evolved in the vertebrates. When they invaded the land environment they faced the same problems that the plants had earlier. All faced new problems of physical support, water balance, temperature fluctuations. The basic limb structure was established in fish: paired pelvic and pectoral fins led to four-limbed animals. The basic bone structure first appears in lobe-finned fishes. Respiration: notice that gills (fleshy projections that flap around in water as they pickup o2 and get rid of co2) are not effective in air (they collapse) and lose huge amounts of water. Lungs evolved out of the digestive tract as fish gulped air when in low o2 environments. In amphibians and early reptiles the lungs were simple sacs. In later reptiles, birds and mammals, they became elaborate chambers with tiny internal compartments. The huge surface area for greater exchange of gases with allowed them to have much higher metabolic rates and activity.

Get access

Grade+20% off
$8 USD/m$10 USD/m
Billed $96 USD annually
Grade+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
40 Verified Answers
Class+
$8 USD/m
Billed $96 USD annually
Class+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
30 Verified Answers

Related textbook solutions

Related Documents

Related Questions