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________increase in metabolic rate and a/an ______increase in the need for oxygen by the fish The higher the water temperature the _____faster 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 Mostly Poikilothetmic Homeothermic Low Metabolic Rate High Metabolic Rate Environment is the primary source of Metabolism is the body temperature primary source of body temperature Invertebrates, fish, amphibians, reptiles 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 Environment Body temperature Body temperature varies with cage maintained at fairly temperature constant levels Desert Spiny Lizard Maintains body temperature at about 930F Whiptail Lizard 0 Mean temperature is between 104 – 106 F, yet it occupies the same environment as the desert spiny lizard The Horned Lizard • Melanophores • Ant specialist • Capillary network in 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 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.