Lecture 14

Question 1

challenges associated with living in aquatic versus terrestrial habitats

Answer 1

buoyancy
- aquatic animals are supported by dense water medium
- terrestrial animals expend more energy counteracting gravity

respiratory function
- water has low O2 conc (2.5% of air con)
- air has high O2 conc

internal water/salt regulation
- organisms on land lose water through evaporation

Question 2

anatomical and physiological features that differ in aquatic and terrestrial animals

Answer 2

terrestrial
- strengthened axial skeleton
- limb reorganization and increased muscle mass
- flexible neck
- lighter skull
- decreased muscle mass in the body wall

Question 3

taktaalik

Answer 3

transition organisms

Question 4

circulatory systems of bony fishes Vs. amphibians

Answer 4

one ventricle; atria partially/ completely spilt

three aortic arches

valve in conus arteriosus controls blood flow to lungs or systemic vessels

well developed lymphatic system with contractile vassels

Question 5

describe threats to amphibian populations/ species

Answer 5

skin makes them more susceptible

more than 1/3 of all species considered at risk

habitat loss, disease, pollutants and climate change