Size and Scale Flashcards
1
Q
Smallest and largest organisms
A
- Smallest organisms = frogs and lizards
- Largest Vertebrate = Blue whale (30m and 170 tonnes)
- is massive variations across and w/in species
2
Q
What happens when a body gets bigger? (2)
A
- Movement and body shape become restricted
- if you double size, you triple (cube) its mass
- Means need greater support - as bones increase in length they increase in width proportionally more
- 5x longer bone needs to be 40x thicker to support
- Stresses on bones greatest at edges (means hollow tubes for bones are stronger)
3
Q
Forces acting on body (3)
A
- Compressive Forces: tend to collapse structures (e.g. weight)
- Tensile Forces: tend to pull apart
e. g. muscles on tendons - Shear Forces: Twisting and sliding of one section on another
e. g. rotation of spine
4
Q
Consequences of large size (6)
A
- Reduced trunk flexibility
- Reduced limb flexion
- Skeletal modification (major support shifts from muscle to bone)
- Limb bones pillar-like, vertical (w/ proximal portions longer than distal)
- Feet large, may be padded (digits usu retained for stability)
- Safety (size protects from most predators)
5
Q
Metabolism and mass
A
- Many processes involve exchange across surface (respiration, digestion) -> SA is limiting factor
- large animals have to increase relative metabolic areas (e.g. length of digestive tract)
6
Q
Energy and body mass
A
-Large bodies easier to maintain (per kilo of body weight)
-small animals require much more energy
WHY:
-need to maintain body heat (has more heat loss if smaller)
-heat loss proportionate to SA
-Larger animals have proportionately more bone
7
Q
Types of Growth - Isometric and Allometric growth
A
- Isometric Growth: All parts grow at relatively the same speed
- geometric similarity retained
- unusual in living organisms (factors of size, gravity and body part functions normally operate)
- Allometric growth: parts do not grow equally
- e.g. human babies -> head doesn’t remain as big in comparison to rest of body)
8
Q
Allometry -what is it
- Positive allometry, isometry and negative allometry
e. g. of kangaroos - male and female muscle
A
- Relative or differential growth of a part in relation to an entire organism or to a standard
- is the study and measure of such growth
- Positive Allometry - where Variable 1 (e.g. height) increases faster than variable 2 (e.g. head size)
- Isometry: constant ratio (both increase at same rate)
- Negative allometry: head size may double, but head size increases by 1.5
e.g. Females have iometry of muscles in limb, whereas males have positive alometry; 2 x bigger male = 2.5 x bigger muscle
9
Q
Bergmann’s Rule and Allen’s Rule
A
- Bergmann’s Rule: Homeothermic animals from higher altitudes and latitudes (or bred at lower temps), tend to be larger
- SA decreased therefore less heat loss - Allen’s Rule: The size of extremities increases from colder to warmer climates in same species (or closely related)
- allows body heat to disperse more readily
*both rules apply to people too
10
Q
Ecological Influences on size
- Island Dwarfism
- Island Giantism
- e.g.
A
- Island Dwarfism: on smaller islands, where less food/resources
- e.g. elephants on Malta and Sicily are smaller than African elephants
- Island Giantism: occurs when there are fewer predators on island so that once small animals can become larger (due to loss of predation pressure)
- e.g. Komodo Dragon, Dodo, larger turtoise
11
Q
Continental size and body size
A
- Maximal body mass relates to size of landmass -> larger animals need larger territories
- Migration from large to small territories results in loss of body mass w/ time
12
Q
Climate change and reducing Body size
A
- 38 of 85 animal and plant species showed reduction in size over decades
- include scottish sheep (5% smaller than 1985)
- Cotton, corn, strawberries, shrimp,l crayfish, Atlantic salmon, frogs, toads
- include scottish sheep (5% smaller than 1985)
