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 surroundingso False- Quiz: true/false: Metabolic heat can be captured and used to maintain the core body temperatureo True- Quiz on Podcast: true/false: conservative estimates predict that within 50 years the Arctic will be ice free year roundo False- Definitionso Poikilotherm: temp conformer Tb=Ta, doesn’t control its temp at allo Homeotherm: temp regulator Tb=constanto Endotherm: body temperature derived from metabolism (humans)o Ectotherm: body temp derived from environment, can control but controls using its surroundingso Thermoregulation: maintaining a constant body temp- Thermoregulation challengeso Marine environment general much colder than Tbo 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 Co Many marine mammals amphibious (pinnipeds) Must thermoregulate in air and water- Maintaining thermal balanceo Heat loss=heat productiono Heat production: metabolism—food+02=heat+H2O+CO2o 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 2/3o Distance heat must travel (L), thicker blubber in whale means the heatmust travel farther to be releasedo Thermal conductivity (k) Differs by substanceo Heat loss (Q)=kA(Th-Tc)/LMarine Mammal Strategies for Thermoregulation- 1. Lower temperature differentialo Change physical location to warmer areas Occurs during physiologically stressful times, such as calvingo 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 sizeo 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 metabolismo Increases heat productiono 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 tempo LCT=lower critical tempo UCT=upper critical tempo Q10 effect (Every time temp increases by 10 degrees it increases metabolic rates of organisms a standard amount)o As temp decreases, metabolic rate increaseso 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 insulationo 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 cm2o 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 isfor insulation, inner blubber may change-energy storage)o Blubber thickness increases as fur density decreaseso Blubber thickness also increases with body size Large organisms use blubber method, smaller organisms use hair methodo Hair traps air inside of it and uses air as an insulator, bigger organismshave larger volume and need insulation to keep all that heat insideo 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 skino 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 deptho Diving with Hair Loss of air=loss of insulation Must maintain air pocket Requires extensive time grooming at surfaceo 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 ratioo 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)o 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- Produces more heat and more capillaries feed it, so heatis shunted to capillaries and into the body as opposed toused in ATP or mitochondriao Thermal Windows: parts of body that aren’t well insulated- 5. Vascular controlo 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 thermoregulationo Huddle together for warmth when it’s coldo Haul out when warm in polar regions, bask in sunlighto Lie in water when too warm- Quiz: radiation, conduction, convection, evaporation, which is primarily influenced by behavioral thermoregulation that occurs when a seal suns itselfon a warm arctic day? RadiationClimate 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 lando Only have