Evolution of Chordates: Temperature Regulation, Respiration, and Circulatory Systems, Slides of Biology

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Nonvertebratechordates

Fishes

Amphibians Reptiles Birds

Mammals

Invertebrate ancestor

 Ectotherm – body temperature is controlled through losing and gaining heat from the environment

 Endotherm –generates and retains heat inside its body

Environmental Temperature (°C)

Body Temperature (°C)

 Blood carries oxygen to the cells

 The circulatory system transports blood and materials throughout the body

 Most chemical reactions in the body take place in water

 Animals (and plants!) had to acquire ways to retain water once they became land-dwelling

 Ectothermic (so are amphibians and reptiles) › Water is a good environment for ectotherms

• the temperature of water doesn’t change as quickly as air temperature

 Use gills for respiration

 External fertilization (so do amphibians)

 Single-loop circulation

Amphibia means ____________________

 Developed strong limb bones for

walking and lungs to breath air

 Amphibians – double loop circulation

› First loop carries blood between the heart and the lungs › Second loop carries blood between the heart and the tissues

 Adapted to terrestrial life

› Dry, scaly skin to keep water in › Modified excretory systems › Shelled eggs that do not require water

 Internal fertilization – increases chances of success, allows a direct means of fertilization › Bird and mammals too!

 Reptiles – double loop circulation

› Most reptiles have 3 chambers, but crocs and alligators have 4

1. In what period do birds first appear in the fossil record? Give the dates of this period.
2. In what period do mammals first appear in the fossil record? Give the dates of this period.
3. Humans are mammals. In what period do humans first appear in the fossil record? Give the dates of this period.

Endotherms generate heat using high metabolic rates, which means they require more __________________!

Birds have feathers

and mammals have

fur to retain heat