How different organisms deal with environmental variation

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How different organisms deal with environmental
variation

• Part TwoAnimals Homeostasis
• Resource availability
• Oxygen
• Stress
• Water balance (salts)
• Excess N
• Heat/Cold

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• Resource availability
• --oxygen (for cell respiration)

organisms gt 2 mm need more than diffusion ex
insects have branching pipes (trachea)
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Ex carrier molecules (hemoglobin, hemocyanin)
? increase carrying capacity of blood ? must
both bind and release O2 readily (according to
the envt)
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Ex1 counter-current exchange (basic diffusion
principles)
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• Stress
• --Water balance (salts)

? Maintaining solute and water balance costs
energy
must drink water, but excrete huge quantities of
salt
kidneys remove some salts from urine
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• Ex splash-pool copepod
• synthesizes amino acids to match
• osmotic potential of the habitat

Ex sharks and rays ? increase blood osmotic
potential w/ urea
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• Stress
• --excess nitrogen

? carnivores consume excess N (why?) ? aquatic
animals excrete ammonia (NH3) ? terrestrial
animals produce less toxic, but more , forms
of N mammals--gt urea birds and reptiles--gt
uric acid (C5H4N4O3)
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• Stress
• --Heat/Cold

? endotherms (mammals and birds) costly
limited work vs. basal metabolism behaviors
can conserve E may starve rather than freeze

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Ex2 counter-current exchange
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Cold stress ex penguins

• Big (decrease surf to vol)
• Subcutaneous blubber (water)
• Fine feathers (ice)
• Huddle up (1000s)
• Flippers and feet
• muscles internal with long tendons
• Blood vessels exchange heat (ex3 countercurrent
  exchange)

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• Stand up to avoid ice
• (my favorite) rock back on heels, lean on tail
  feathers, and stand like a tripod!

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partial homeostasis maintain specific areas
of their bodies --enter states of torpor
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? ectotherms (typically amphibians and
insects) --adjust behavior, microclimate
www.studentorganizations.missouristate.edu
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Each species functions best under a (relatively)
narrow range of conditions. Examples of
species that are well-adapted to --Polar
regions? --Desert? --Prairie?