Temperature Regulation

Temperature Regulation
Modes of Heat Loss and Heat Gain

Radiation

Conduction

Convection

Evaporation
Body Temp = Heat Produced + Heat Gained
(By Metabolism)
–
(From Environment)
Heat Lost
(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
increase in metabolic rate and a/an ______
increase in
a/an________
the need for oxygen by the fish
faster the
The higher the water temperature the _____
fish has to move its operculum to ventilate the gills
Operculum covers gills
Large
Mouth
Bass
Brook
Trout
The Desert Iguana
Critical Thermal Maximum = 470C or 1170F
Most Lizards Escape Heat in Burrows
• The desert iguana, like other
lizards, is slow moving and
vulnerable to predators when
it 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 network
in head
• Horns as antipredator 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 body
temperature is
about 800F
• Uses urinary
bladder as a
canteen
The Desert Tortoise
• Burrows to escape heat
• Burrows during
hibernation
• Estivation – summer
inactivity
An Endangered Species
Torpor: Hummingbirds
Body temperature and oxygen
consumption (red line) are high
when hummingbirds are active
during the day but may drop to
1/20 these levels during periods
of food shortage.
Dawn
Dusk
Torpor: Deer Mouse
• Most widely distributed mammal
in North America
• Found from below sea level in
Salton 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 40-70
beats per minute to about
8-12 beats per minute
• Body temperature drops 3-50C
• The biggest difference between
bears and other hibernators is
that once a bear is down it
does not wake up to defecate,
urinate, or eat all winter
Golden Mantle Ground Squirrel