Acquiring Energy
and Nutrients
Heterotrophy
Osmotrophy: DOM
surface
to volume ratios
Requires
N & P
Refractory
vs Labile and growth
Phagotrophy:
Herbivory, Carnivory, Omnivory, Detritivory
Plants mostly
carbon- carbohydrates-cellulose-refractory
Many herbivores
lack cellulase
Use gut
symbionts to convert cellulose into fatty acids, vitamins, and small organic
molecules that can be absorbed
High C:N ratio,
high protein plant material
preferred: new growth, species preferences
Mineral
deficiencies: Sodium often limiting to herbivores:
Salt licks,
enriched areas preferred and feedback
Detritivores:
refractory food source microbial enrichment
Omnivory:
seasonal
Energy
Heat manifests
itself as kinetic energy of atoms, molecules:
creamer
in coffee, rate of chemical reactions: crickets crirping,
(((Chirps/min)
- 40) / 4) + 50 = degrees F
Measuring
energy
Loss of
potential energy (biomass, substrates, electric potential)
Calorimeter:
measuring heat as a parameter of energy utilization
1 Calorie =
energy neeeded to increase temperature of 1 g of water one degree from
14.5˚C
Heat of
Combustion provides caloric content of compounds
Calorimeters
indicated that living cells are governed by the same physical-chemical laws
that describe energy transformations in the inanimate world. Figure 9.3
Oxygen
consumption, CO2 evolution, and heat production all balance as if
measuring oxidation of carbon substrates.
bacteria: manure
piles, hay fires
bees, fish, mammals/birds
Life as a state
of sustained Potential Energy:
heat is produced
in maintaining low entropy
chemical order,
bio-synthesis, storage products
bioelectricity:
electrophysiology, membrane potentials,
proton
motive force
Energetics of
living organisms, Energy budgets
Energetic
Efficiencies of living systems:
Assimilation
Refractory vs labile, intake
Respiration
(metabolism):
size, temp, intake, stress, activity, SDA
Excretion
(of potential and kinetic energy)
1)Maintainence
Energy-Standard Metabolic Rate: fluctuates with potential energy input
Well fed
organisms more wasteful, more discriminant, high metabolic rate
Starved organisms under stringent control, slow metabolic
rate, no discrimination: protozoans 1-2% of growing rate.
SMR increases
with decreasing body size for homothermic Fig. 8.14.
Minimum
size for poikilotherms less: surface to volume: unique body shapes
2) Cost of a
Free Existence: activities necessary for survival
motion, food
capture, predator avoidance
3) Productive energy: energy expendature
greater than standard metabolism used to decrease entropy-catabolism, biomass
production, storage
Poikilotherms: body
temp and metabolism fluctuate (Fig 8.9)
behavioral
control of heat balance: Fig 3-2; Fig 8.11.
microclimate usage
change
in body shape, color, position Fig 8.12
Adaptation to
temperature regimes:
Antarctic mites,
evergreens, plant seeds, Euplotes fig 5-3
Freeze
tolerance: glycerol, antifreeze peptides
Acclimation:
Fig 8.10
Homeotherms:
physiological control of heat balance:
requires food
rich habitat in addition to minimum size
Heterotherms: periodic regualation of body temp.
Adaptations for
mixed temperature regulation:
Tropical
plant
Tuna
Swordfish
brain, eyes
temporary
homoethermy for egg incubation in some reptiles
True
Hibernation: some rodents: groundhogs, marmots
Most
mammals store fat to maintain homeothermy (bears)
Or
store food (chipmunks, squirrels)
Water Balance:
Osmolarity
Hypoosmotic-
Hypotonic internal more dilute than outside: marine verts
Getting
rid of salt: tears, gills, concentrated urine
human
urine 2.2%, whales > than 3%
Isoosmotic-
Isotonic: same marine inverts
Hyperosmotic-
freshwater verts
Getting
rid of water; urine
Anadromous
fishes
Osmoregulation/Osmoconforming
Desert:
metabolic water, highly efficient kidneys
Water
loss: rabbits 50%, Camels 27%, Humans, 10-20%
Light:
UV: mutagenic,
vitamin D
Photoperiod:
light and dark proportions
Much of life
reactive to photoperiod:
circadian
rhythms, biological clocks
sustained
behavior in absence of stimulus
genetic
basis; per, tim, cry: clock proteins
Life cycles controled by hormonal response to critical day
periods:
Bird
reproduction, antlers and breeding cycles (Fig 8.25)
Tidal and Lunar
cycles
Crabs,
Ciliates
Spring-Neap
cycle: Grunion, Fundulus