Size & Scaling (W2) Flashcards
Scaling?
= the structural & functional consequences that occur due to changes in size.
Who is the person behind the scaling theory and what year?
• Galileo Galilei.
• 1638.
3 Engineering Principles of Scaling to maintain performance of a structure?
• Change dimensions.
• Change materials.
• Change architecture/anatomy.
Change dimensions?
= states that as the structure scales, the proportional dimensions might change as well.
Changing materials?
= states that materials and their properties directly affect scaling.
Changing architecture/anatomy?
= states that as the structure scales, the architecture changes.
Why doesn’t the T-rex catch the Jeep?
• As muscle strength increases, cross-sectional area increases &
• As body mass increases, volume increases.
Therefore, because muscle strength doesn’t scale as fast as muscle mass the T-rex doesn’t have the strength to move the muscle gained through increased body mass.
Explain the relationship between scaling, metabolism & endurance. (2)
• Since small animals like shrews and hummingbirds burn through their fat reserves very quickly (high metabolism), they tend to turn to torpor in order to reserve more energy (endurance).
• On the other hand, because large animals like bears burn through their fat reserves at much slower rates (low metabolism) they tend to turn to hibernation (endurance).
Explain the relationship between scaling and time.(2)
• The bigger you are (increased body mass), the slower your heartbeat, the slower your respiration rate and the longer your lifespan.
[Eg. Mice & Elephants].
• Physiological time scales differentially with clock time.
[Eg. Tortoise].
Explain relationship between scaling and skeleton mass in mammals & birds.
At any given body mass, it turns out that the skeleton mass of birds is the same as the skeleton mass of mammals but:
• Birds have denser skeletons (in some areas).
• Birds have bone geometry that increases stiffness & strength at smaller sizes.
Allometry?
= where scaling changes are not proportional across measured variables.
Isometry?
= where scaling changes are proportional across measured variables.
State Kleiber’s Law
= states that our metabolism does not grow proportionally with our body weight.
State the Surface rule?
= states metabolism is predicted to scale to the ⅔power relative to body mass.
What is ontogeny?
= involves organism development.
Allometry & Ontogeny?
Because an organism’s development occurs, body proportions may change allometrically. Therefore, this poses a problem for paleontologists as they may mistake such an occurrence for species-level distinction & confuse the different developmental stages for different species.
Paedomorphosis?
= an occurrence where an organism retains its juvenile proportions into adulthood.
Simpler way of defining scaling?
= as animals get bigger, their anatomical & physiological features differ.
Explain Galileo’s theory?
Noticed that animals don’t scale proportionally as they go and that scaling often applied in Engineering could be applied to biology as well.
How do engineers & animals overcome problems due to scaling?
They use the 3 Engineering principles.
Eg of Changing dimensions in Engineering?
Irish wall & Great wall of China
= the taller the wall, the thicker the base should be to maintain structure stability.
Eg of Changing dimensions in Biology?
Tetrapods
= as an animal gets bigger, the thickness of the skeleton may increase.
Eg of Changing materials in Engineering?
Philadelphia city wall & Burj Khalifa
= tallest masonry building (167m) vs tallest steel building (829.8m).
Eg of Changing materials in Biology? (2)
• Evolution of bone from cartilage/poor ossification to bone.
• Tetrapods
= alter bone density & cross-sectional geometry to shift to new material properties (Kestrel vs Penguin).
Eg of Changing architecture in Engineering?
Danhe bridge & Golden gate bridge
= compression bridge vs tension bridge (better).
Eg of Changing architecture in Biology? (2)
Tetrapods
= either means this or that:
• Change in posture (eg Kangaroo).
OR
• A novel adaptation.
Novel adaptation?
= a feature that enables thicker & bigger animals to exist.
Running?
= moving your body mass using your muscle strength.
Do birds have proportionally lighter skeletons than mammals?
No, birds have the same skeletal mass as that of mammals but birds have denser skeletons on some areas & have bone geometry that increases stiffness & strength at smaller sizes.
Eg of answer to bird & mammal skeleton mass?
Seen in a comparison between Kestrel & Penguin.
Torpor?
= involuntary state that an animal enters into when conditions dictate as a survival tactic to survive winter conditions & occurs over short periods of time (several times a day).
Hibernation?
= voluntary state that an animal enters into to (i) conserve energy, (ii) survive through food scarcity & (iii) minimize their need to face elements in cold, winter months & it occurs over long periods of time (days, weeks, months).
