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Temperature Regulation
Modes of Heat Loss and Heat Gain
Radiation
Conduction
Convection
Evaporation
Body Temp = Heat Produced + Heat Gained – Heat Lost(By Metabolism) (From Environment) (To Environment)
Temperature Tolerances
CTmin CTmax
The Desert Pupfish
Critical Thermal Maximum = 430C or 109.40F
Triple Jeopardy An increase in water temperature results in a
decrease in the oxygen content of the water
An increase in water temperature results in an increase in fish temperate. This results in a/an________ in metabolic rate and a/an ______ in the need for oxygen by the fish
The higher the water temperature the _____ the fish has to move its operculum to ventilate the gills
increase increase
faster
LargeMouthBass
BrookTrout
Operculum covers gills
The Desert Iguana
Critical Thermal Maximum = 470C or 1170F
Most Lizards Escape Heat in Burrows
• The desert iguana, like otherlizards, is slow moving andvulnerable to predators whenit first emerges in the morning
Amphibian, Reptile, or Bird?Endotherm or Ectotherm?
Amphibian, Reptile, or Mammal?Endotherm or Ectotherm?
Bird, Reptile, or Mammal?Endotherm or Ectotherm?
Amphibian, Reptile, or Bird?Endotherm or Ectotherm?
Amphibian, Reptile, or Bird?Endotherm or Ectotherm?
Ectothermy Versus Endothermy Mostly
Poikilothetmic
Low Metabolic Rate Environment is the
primary source of body temperature
Invertebrates, fish, amphibians, reptiles
Mostly Homeothermic
High Metabolic Rate Metabolism is the
primary source of body temperature
Birds and mammals
Poikilothermic Animal with a fluctuating body
temperature.
Most ectotherms are poikilothermic
Homeothermic An animal that maintains a fairly
constant body temperature
Most endotherms are homeothermic
Ectotherms: Behavioral Temperature Regulation Laboratory
Body temperature varies with cage temperature
Environment Body temperature
maintained at fairly constant levels
Desert Spiny Lizard Maintains body temperature at about
930F
Whiptail Lizard Mean temperature is between 104 – 1060F, yet it
occupies the same environment as the desert spiny lizard
The Horned Lizard
• Melanophores
• Ant specialist
• Capillary networkin head
• Horns as anti-predator device?
The Coachwhip or Red Racer
A lizard eating snake
Kangaroo Rat
•Endothermic
•Nocturnal
•Burrowing
Water Balance In The K-Rat
When are most mammals active in the desert? Why?
Big horn sheep
Antelope Ground Squirrel
• A poikilothermic endotherm
• Diurnal
The Desert Tortoise
• Preferred bodytemperature isabout 800F
• Uses urinarybladder as a canteen
The Desert Tortoise
• Burrows to escape heat
• Burrows during hibernation
• Estivation – summer inactivity
An Endangered Species
Torpor: HummingbirdsBody temperature and oxygenconsumption (red line) are highwhen hummingbirds are activeduring the day but may drop to 1/20 these levels during periodsof food shortage.
Dawn Dusk
Torpor: Deer Mouse• Most widely distributed mammal
in North America
• Found from below sea level inSalton Sea area to 11,200 ft. in the southern Sierra Nevada in California
Hibernation: Black Bears• Many textbooks say bears do not
hibernate – This is not true
• Heart rate drops from 40-70beats per minute to about8-12 beats per minute
• Body temperature drops 3-50C
• The biggest difference betweenbears and other hibernators isthat once a bear is down it does not wake up to defecate, urinate, or eat all winter
Golden Mantle Ground Squirrel