Temperature regulation and metabolism Heterothermy Daily Seasonal Myotis Tenrec Bradypus Macaca Homeothermy
Jan 08, 2016
Temperature regulation and metabolism
HeterothermyDaily Seasonal
Myotis
Tenrec
Bradypus
Macaca
Homeothermy
Costs of Endothermy
metabolic response to temperature extremes
Ambient temperature
low high
Metabolic rate and body size
SMALL MAMMALSLarger relative surface area
Higher rates of heat exchange
Coping with seasonal environments -- Migration
Lasiurus cinerea
Lasionycteris noctivagans
Lasiurus cinerea
COPING WITH COLD
Subnivean zone
-30° -20° -10° 0°
Snowsurface
Temperature profile
Mouse runways gopher “eskers”
Heterothermy
Heterothermy
Homeothermy
Eptesicus fuscus
Thermal neutral zone
Heterothermy -- Daily torpor
Chaetodipus californicus
10 h torpor bout
Heterothermy -- Daily torpor
85% energy savings
Seasonal heterothermy
Hibernation (winter dormancy)
Spermophilus parryii
arousal bout
Seasonal heterothermy
Hibernation + Aestivation(winter + summer dormancy)
Spermophilus mollis
Active 4 months(spring growing season)
Dormant 8 months(hottest AND coldest months)
Temperature (°C)-5 10 15
Soil temperature profile -- Great Basin
Ammospermophilus leucurus
Year-round daytime activityBUT
Seasonal shift in behavior
Behavioral & Physiological tolerance
August
January
COPING WITH HEAT
Summer heat avoidance
Surface activity bouts (and resting in shade)
underground
Daily activity profile (mid-summer)
Desert Animals Potential evaporative water loss
SMALL MAMMALSLarger relative surface area1) Higher heat loads2) Higher evaporative loss
Burrow microclimate
Sundevall’s Jird(Meriones crassus)
Negev Desert, Israel
Daytime (underground)
Temperature
Burrow
Surface
Relative Humidity
Burrow
Surface
Mid-summer profiles
Water conservation in desert rodents
Merriam’sKangaroo rat(Dipodomys
merriami)
SouthwesternUS
Water conservation in desert rodents
Ord’s kangaroo rat (Dipodomys ordii) Western US
Kidney structure and water conservation
Dilute Concentrated
1200
med
ull
a
Dromedary(Camelus
Dromidarius)
Bactrian Camel(Camelus bactrianus)
Guanaco(Lama guanaco)
Desert adaptations in large mammals (Camelidae)
Keeping the brain cool
Countercurrent heat exchange
Keeping extremities warm
Marine mammals
Temperature regulation
depth (m) duration (min)Humans skin diver 100 2 scuba 300
Deep Diving
Human technology attack submarine test depth 400 “crush” depth 600 research submarine Alvin 4,500 bathyscaphe Trieste 10,912Otariidae fur seal 200 8 sea lion 250 10
Phocidae Harbor seal 200 10 Weddell seal 600 73 Elephant seal 1,600 90
Whales Fin whale 500 20 Pilot wale 610 Beluga 650 20 Killer whale 1,000+ Sperm whale (feeding) 500-1000
(record) 3,200 80 (maximum) ?
DEEP DIVING feeding dives of sperm whale (Physeter macrocephalus)
Elephant Seal Diving
Animals Dives Duration (min)
Surface Interval (min)
Mean Max Mean
21 Females
116,555 24 89 2
15 Males 100,662 23 80 3
Depth (m)
Mean
Max
493 1567
365 1581
DEEP DIVING -- feeding dives of elephant seal (Mirounga angustirostris)
DIVING PROBLEMS
Problem 1 -- Oxygen supply
Physiological adaptations: Increased blood volume & hematocrit more hemoglobin and myoglobin selective shunting of blood, lower heart rate lower metabolic expenditure higher tolerance of CO2 & lactic acid
Phoca vitulina (common harbor seal)
DEEP DIVING Diving Bradycardia - lower heart rate, blood diverted to essential organs
From: Elsner (1988)
DEEP DIVINGReduced energy expenditure during dive
Passive gliding descentActive stroking
(Mirounga angustirostris)
Problem 3 -- Nitrogen Decompression sickness the “bends”
Nitrogen narcosis
DIVING PROBLEMS
Problem 2 – Water pressure
Sperm whale (Physeter macrocephalus)
Spermaceti organ
Possible functions:
Hydrostatic
Echolocation
Weapon (ram)
DIVING PROBLEMS
Problem 4 -- Navigation
Foraging at depths where there is little or no ambient light
Toothed whales sophisticated underwater sonar
Seals -- Don’t have echolocation
Acute “passive” hearingHigh visual acuitySensitive tactile vibrissae