Thermoregulation Quiz which of the following is NOT a way that heat can be gained or lost at the body surface Evaporation convection induction conduction or radiation o Induction Quiz true false An ectotherm controls its internal temperature while an endotherm takes on the temperature of its surroundings o False Quiz true false Metabolic heat can be captured and used to maintain the core body temperature o True Quiz on Podcast true false conservative estimates predict that within 50 years the Arctic will be ice free year round o False Definitions o Poikilotherm temp conformer Tb Ta doesn t control its temp at all o Homeotherm temp regulator Tb constant o Endotherm body temperature derived from metabolism humans o Ectotherm body temp derived from environment can control but controls using its surroundings o Thermoregulation maintaining a constant body temp Thermoregulation challenges o Marine environment general much colder than Tb o Water conducts heat 25x faster than air High specific heat due to Hydrogen bonds in water 1 calorie to raise 1 g water 1 degree C o Many marine mammals amphibious pinnipeds Must thermoregulate in air and water Maintaining thermal balance o Heat loss heat production o Heat production metabolism food 02 heat H2O CO2 o Heat loss Convection heat transfer to a fluid movement of air or water conduction heat transfer to a solid radiation transfer of radiant energy evaporation heat transfer by changing water from liquid to gas respiratory water loss What controls heat transfer o Surface area A Varies with body mass 2 3 double body mass means SA increases by 2 3 o Distance heat must travel L thicker blubber in whale means the heat must travel farther to be released o Thermal conductivity k Differs by substance o Heat loss Q kA Th Tc L Marine Mammal Strategies for Thermoregulation 1 Lower temperature differential o Change physical location to warmer areas Occurs during physiologically stressful times such as calving o Decrease body temperature Typical mammalian Tb 36 38 dC Cetacean Tb 35 5 dC Generally lower while diving to reduce metabolism and therefore O2 needs hypometabolism 2 Increase body size o Decrease SA to volume ratio lose heat small gain heat big o Quiz explain to your neighbor why increasing body size can help in thermoregulation 3 Increase metabolism o Increases heat production o Metabolism Rubner s law BMR mass 2 3 Kleiber s Law BMR mass 3 4 Basic metabolic rate Thermal Neutral Zone TNZ o TNZ zone in which endotherms do not need to regulate temperature temp can change but metabolic rate doesn t need to in order to maintain temp o LCT lower critical temp o UCT upper critical temp o Q10 effect Every time temp increases by 10 degrees it increases metabolic rates of organisms a standard amount o As temp decreases metabolic rate increases o Metabolic rate increases as temp goes up after TNZ to get rid of excess heat Q10 effect too Quiz As animals become larger their mass specific metabolic rate must change in order to maintain the same internal temperature Specifically it must decrease As you get larger the SA does increase as fast as the volume so you don t need to produce as much heat per body mass 4 Increase insulation o Decrease conductance Increase thickness of blubber layer Increase density or length of hair Traps air among hairs and air provides insulation Sea otters 125 000 hairs per cm2 o Fur vs Hair Hair modifications for aquatic life flatter hairs shorter hairs longer scales on hairs denser hairs Blubber modifications for aquatic life stratified layers outer is for insulation inner blubber may change energy storage Blubber thickness increases as fur density decreases Blubber thickness also increases with body size Large organisms use blubber method smaller organisms use hair method Hair traps air inside of it and uses air as an insulator bigger organisms have larger volume and need insulation to keep all that heat inside Blubber Advantages Can withstand fouling does not compress with depth able to dump heat energy store Disadvantages live tissue at low temps difficult to grow or divide at low temps must haul out to molt heal shed skin Fur Advantages lighter better insulation for given amount skin is maintained at or near body temp ability to repair skin molt etc in the water b c they can maintain the body temp Disadvantages requires air layer needs to be kept clean insulation declines with depth Diving with Hair Loss of air loss of insulation Must maintain air pocket Requires extensive time grooming at surface Quiz metabolic rates in adult sea lions Different than juveniles metabolic rates for temp increase metabolic rates by swimming to maintain body temp for juveniles Why would juveniles experience more metabolic stress than adults SA to volume ratio How to respond to seasonal changes Change amount of blubber gets thicker when it s colder Change quality of blubber change to saturated fats every available spots on a C are being made to a saturated fat by bonding to H unsaturated fats have C double bonded to other C What about pups Lanugo fine hair birth coat that is very dense Works in air not waterproof Brown fat specialized adipose tissue Non shivering thermogenesis o o o o o o o o o Produces more heat and more capillaries feed it so heat is shunted to capillaries and into the body as opposed to used in ATP or mitochondria o Thermal Windows parts of body that aren t well insulated 5 Vascular control o Counter current heat exchange heat instead of oxygen in fish Veins carry cold artery holds warm heat constantly flowing from artery to vein Most important in peripheral body parts Dolphins and lunge feeding whales 6 Behavioral thermoregulation o Huddle together for warmth when it s cold o Haul out when warm in polar regions bask in sunlight o Lie in water when too warm Quiz radiation conduction convection evaporation which is primarily influenced by behavioral thermoregulation that occurs when a seal suns itself on a warm arctic day Radiation Climate Change Warming oceans are reshaping fisheries Marine environment organisms moving towards the poles away from tropics as things get hotter much faster than organisms on land o Only have tropical warm water fish left Quiz discuss with your neighbor how thermoregulation will interact with respiration and with energy budgets as climate change progresses Are the species that disappear from tropical areas due to warming simply moving b c of temperature tolerances o As temp increases it requires