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