1. MAINTAINING OXYGEN SUPPLY, WATER BALANCE & BODY TEMP CH. 7 OBJECTIVES 16-24

2. SECTION 7.5 ANIMALS REQUIRE OXYGEN TO RELEASE ENERGY CONTAINED IN FOOD What process in animal cells requires oxygen? How is the process of acquiring oxygen different for terrestrial and aquatic animals? © 2015 Pearson Education, Inc.

3. SECTION 7.5 ANIMALS REQUIRE OXYGEN TO RELEASE ENERGY CONTAINED IN FOOD Recall: Animals use aerobic respiration to covert the energy in organic compounds into energy that cells can use Most organisms are oxygen regulators are able to maintain normal oxygen consumption levels even when environmental oxygen levels drop below normal © 2015 Pearson Education, Inc.

4. SECTION 7.5 ANIMALS REQUIRE OXYGEN TO RELEASE ENERGY CONTAINED IN FOOD Atmospheric oxygen is readily available in terrestrial environments Minute organisms acquire oxygen by diffusion Larger organisms cannot use direct diffusion across the body surface insects have spiracles (openings) on the body wall that lead to tracheal tubes to supply oxygen to the body terrestrial vertebrates have lungs that allow oxygen to diffuse into the bloodstream that carries it to the cells some amphibians also use moist vascular skin © 2015 Pearson Education, Inc.

5. FIGURE 7.9A © 2015 Pearson Education, Inc. (a) Insect Air sacs Tracheae Spiracle

6. FIGURE 7.9B © 2015 Pearson Education, Inc. (b) Mammal Lungs Heart

7. SECTION 7.5 ANIMALS REQUIRE OXYGEN TO RELEASE ENERGY CONTAINED IN FOOD In aquatic environments, oxygen may be limiting may be problematic to acquire maybe taken from the water or from the atmosphere Some animals are oxygen conformers mainly sedentary marine invertebrates such as anemones, jellyfish, starfish Minute animals, like plankton, take up oxygen by diffusion © 2015 Pearson Education, Inc.

8. SECTION 7.5 ANIMALS REQUIRE OXYGEN TO RELEASE ENERGY CONTAINED IN FOOD Most larger aquatic animals have gills vascular outfoldings of the body surface that are in direct contact with the water and exchange gases some gills are simple and distributed over the body some gills are complex and restricted to a specific region © 2015 Pearson Education, Inc.

9. FIGURE 7.9C © 2015 Pearson Education, Inc. (c) Scallop Gills

10. FIGURE 7.9D © 2015 Pearson Education, Inc. (d) Fish Gill arches Heart Mouth open Operculum cavity Operculum closed Mouth closed Gill bar Gill filaments Operculum open

11. SECTION 7.5 ANIMALS REQUIRE OXYGEN TO RELEASE ENERGY CONTAINED IN FOOD Some aquatic animals must surface for oxygen aquatic insects have a tracheal system and surface to fill it with air aquatic turtles and mammals have lungs Some fish have a labyrinth organ to absorb oxygen from air that is gulped into the mouth from the surface (bettas) © 2015 Pearson Education, Inc.

12. SECTION 7.6 ANIMALS MAINTAIN A BALANCE BETWEEN THE UPTAKE AND LOSS OF WATER Water balance = balance between the uptake and loss of water with the surrounding environment How do terrestrial animals gain and lose water? How do aquatic animals gain and lose water? © 2015 Pearson Education, Inc.

13. SECTION 7.6 WATER BALANCE IN TERRESTRIAL ANIMALS Terrestrial animals gain water drinking and eating cellular respiration (remember cellular respiration equation) Terrestrial animal lose water through urine and feces water is reabsorbed across the cloaca in birds & reptiles mammalian kidneys can reduce water loss evaporation from the skin exhaling moist air © 2015 Pearson Education, Inc.

14. SECTION 7.6 WATER BALANCE IN TERRESTRIAL ANIMALS Some animals migrate, leaving areas during the dry season © 2015 Pearson Education, Inc.

15. SECTION 7.6 WATER BALANCE IN TERRESTRIAL ANIMALS Some animals in arid regions enter estivation avoid effects of drought through a period of dormancy (physiological inactivity) Spadefoot toads in the desert southwest © 2015 Pearson Education, Inc.

16. SECTION 7.6 WATER BALANCE IN TERRESTRIAL ANIMALS Many insects undergo diapause enter a stage of arrested development in their life cycle emerge when conditions improve © 2015 Pearson Education, Inc.

17. SECTION 7.6 WATER BALANCE IN TERRESTRIAL ANIMALS Desert mammals show many adaptations to dry conditions active only at night, remaining in a burrow during the day extract water from the food they eat Produce very concentrated urine and/or dry feces tolerate a level of dehydration Ex - desert rabbits may lose water up to 50 percent of body weight in dry periods © 2015 Pearson Education, Inc.

18. SECTION 7.6 WATER BALANCE IN AQUATIC ANIMALS Freshwater animals are hyperosmotic They have a higher salt concentration in their bodies than the surrounding water. Which way does the water flow between these organisms and the environment? Into their bodies from the environment Challenge is maintaining this higher salt concentration inside the body © 2015 Pearson Education, Inc.

19. SECTION 7.6 WATER BALANCE IN AQUATIC ANIMALS Freshwater bony fish are osmoregulators. They drink very little water Produce large amounts of dilute urine They take up sodium and chloride ions by pumping them across their gills; active transport is energetically expensive © 2015 Pearson Education, Inc.

20. FIGURE 7.12A © 2015 Pearson Education, Inc. Absorbs water through skin Hyperosmotic Actively takes up ions through gills Drinks little water Excretes dilute urine (a) Osmoregulation in a freshwater environment Movement of water Movement of ions

21. SECTION 7.6 WATER BALANCE IN AQUATIC ANIMALS Marine animals are hypoosmotic They have a lower salt concentration in their bodies than the surrounding water. Which way does the water flow between these organisms and the environment? Out of the body into the environment Challenge is to retain water, avoid dehydration © 2015 Pearson Education, Inc.

22. SECTION 7.6 WATER BALANCE IN AQUATIC ANIMALS Marine animals have different approaches to water balance Some marine animals are isosmotic (osmoconformers) – body fluids have the same osmotic pressure as the seawater jellyfish, many mollusks, sea anemones © 2015 Pearson Education, Inc.

23. SECTION 7.6 WATER BALANCE IN AQUATIC ANIMALS Many marine organisms are osmoregulators marine bony fish they drink water and absorb it into their gut produce small amounts of concentrated urine they excrete sodium and chloride ions by pumping them across their gills; active transport is energetically expensive © 2015 Pearson Education, Inc.

24. FIGURE 7.12B © 2015 Pearson Education, Inc. Movement of water Movement of ions Hypoosmotic Loses water through skin Drinks ample water Excretes ions through gills Direction of water movement (b) Osmoregulation in a saltwater environment Excretes concentrated urine Direction of ion movement (Na , K , Cl  )

25. SECTION 7.6 WATER BALANCE IN AQUATIC ANIMALS Many marine organisms are osmoregulators cartilaginous fish (sharks and rays) retain urea in their body tissues so they are at a slightly higher concentration than the seawater birds and sea turtles drink seawater and excrete the salt through salt glands marine mammals eliminate salt through their kidneys © 2015 Pearson Education, Inc.

26. MAINTAINING BODY TEMP Consider a simple thermal model of an animal’s body: the body core temperature (T b ) must be regulated within a defined range the temperature of the environment surrounding the body (T a ) varies the temperature at the body surface (T s ) is different from both the core and the environment boundary layer – thin layer of air or water at the body’s surface, within hair, feathers or scales © 2015 Pearson Education, Inc.

27. MAINTAINING BODY TEMP an animal’s body temperature gradually changes from the core to the body surface The body core is separated from the surface by layers of muscle and fat – insulation (L) that affects the animal’s thermal conductivity © 2015 Pearson Education, Inc.

28. FIGURE 7.13 © 2015 Pearson Education, Inc. Muscle and fat Body core TbTb L 1 2 Environment TaTa Body surface TsTs

29. MAINTAINING BODY TEMP Terrestrial animals have much larger changes to their thermal environment than aquatic animals Aquatic animals generally have a lower tolerance for temperature changes Animals regulate body temperature through behavior physiology morphology Animals must sense and respond to their thermal environment © 2015 Pearson Education, Inc.

30. MAINTAINING BODY TEMP Poikilotherms – animals that have a variable body temperature Homeotherms – animals that have a constant, or nearly constant, body temperature These terms are not synonymous with conformers and regulators Only true thermo-conformers are animals that live in environments with almost no variation in temperature such as the deep ocean Homeotherms & Poikilotherms are both generally considered regulators © 2015 Pearson Education, Inc.

31. MAINTAINING BODY TEMP Ectothermy – process of maintaining body temperature through exchange of thermal energy with the surrounding environment animals that do this are ectotherms Endothermy – process of maintaining body temperature through internally generated metabolic heat animals that do this are endotherms How do ecotherm and endotherm relate to poikilotherm and homeotherm? © 2015 Pearson Education, Inc.

32. POIKILOTHERM BODY TEMP Performance varies as a function of body temperature in poikilotherms This includes: locomotion growth development reproduction survivorship © 2015 Pearson Education, Inc.

33. POIKILOTHERM BODY TEMP Each species has high and low temperatures (T min and T max )at which performance approaches zero Each species has temperature(s) at which performance is optimal (T opt ) © 2015 Pearson Education, Inc.

34. 400 600 800 1200 1000 182022242628303234363840 Body temperature (  C) Body temperature.5 1 0 Tolerance range “Optimal” temperature (T opt ) Upper critical temperature (T max ) Lower critical temperature (T min ) Relative performance Sprint speed (mm per sec)

35. POIKILOTHERM BODY TEMP Characteristics of poikilotherms include low metabolic rate high thermal conductivity What does this mean about the insulating properties of L (fat and muscle) in the body? The L layer is relatively small; have less fat (insulation) than homeotherms aerobic respiration during normal activity under increased activity and stress, most energy is produced anaerobically – not sustainable limited to short bursts of physical activity, rapidly become physically exhausted © 2015 Pearson Education, Inc.

36. POIKILOTHERM BODY TEMP Poikilotherms use mainly behavioral thermoregulation Seeking out appropriate microclimates environmental temperatures allow near optimal body temperatures bask in the sun to warm rest in the shade to cool Change conduction between the animal and rocks/soil by raising and lowering the body changing the body shape © 2015 Pearson Education, Inc.

37. FIGURE 7.16 © 2015 Pearson Education, Inc. Time of day 10 20 30 40 50 0500100015002000 Temperature (  C)

38. FIGURE 7.17 © 2015 Pearson Education, Inc. 17  C 18  C 30  C 14  C 16  C

39. POIKILOTHERM BODY TEMP Ectotherms in cold climates endure long periods of temperatures below freezing – how do they withstand this without freezing solid? Supercooling of body fluids – the body temperature falls below the freezing point of water but does not freeze solutes in the blood lower the freezing point animals from many different groups increase the glycerol in body fluids protects against freezing damage © 2015 Pearson Education, Inc.

40. POIKILOTHERM BODY TEMP Some aquatic invertebrates and aquatic insects do freeze, then thaw when temperatures rise More than 90 percent of the body fluid freezes remaining fluids have a high solute concentration ice is present outside the shrunken cells muscles and organs become distorted After thawing, normal shape is restored © 2015 Pearson Education, Inc.

41. HOMEOTHERM BODY TEMP Birds and mammals produce heat through aerobic cellular respiration this process is not 100 percent efficient energy is lost as heat Allows homeotherms to… sustain activity for long periods of time live in a wider range of thermal environments generate energy rapidly when needed © 2015 Pearson Education, Inc.

42. FIGURE 7.19 © 2015 Pearson Education, Inc. Elephant Human Cat Dog Squirrel Mouse Body mass (kg) 10.10.01100010010 10 6 10 5 10 4 10 3 10 2 10 Oxygen consumption (cm 3 /hr)

43. HOMEOTHERM BODY TEMP Thermoneutral zone – the range of environmental temperatures within with the metabolic rates of homeotherms is minimal outside of this zone, past the critical high and low temperatures, metabolic rate increases Most homeotherms have a body temp set point around 40 o C If the environmental temp is outside of thermoneutral range, physiological mechanisms kick in (shivering, sweating, etc…) © 2015 Pearson Education, Inc.

44. FIGURE 7.20 © 2015 Pearson Education, Inc. Lower critical temperature Upper critical temperature Thermoneutral zone Ambient temperature Resting metabolic rate

45. HOMEOTHERM BODY TEMP Homeotherms use some type of insulation to regulate heat exchange between body and environment What are some examples of this insulation? © 2015 Pearson Education, Inc.

46. HOMEOTHERM BODY TEMP Fur – mammals – insulation value varies with thickness Thickness usually greater in larger mammals smaller mammals are limited in the amount of fur they can carry because it can limit movement Fur thickness can change with season – acclimation Aquatic mammals often have no hair instead have a layer of fat beneath the skin = blubber Some insects have a fur-like coat on the thoracic region – retains high temperature for flight muscles © 2015 Pearson Education, Inc.

47. HOMEOTHERM BODY TEMP Feathers – birds – heat loss is reduced when the feather are fluffed Also draw their feet into the body some Arctic birds have feathered feet Arctic and Antarctic birds have a layer of fat beneath the skin © 2015 Pearson Education, Inc.

48. HOMEOTHERM BODY TEMP Shivering – involuntary muscle action that increases heat production Brown fat – some small mammals burn brown fat, which has many more mitochondria and generates more heat found in hibernators such as bats and groundhogs © 2015 Pearson Education, Inc.

49. HOMEOTHERM BODY TEMP Insulation also keeps heat out of the body Animals from hot environments must rid themselves of excess body heat lean, lanky build large ears, appendages for greater surface area – radiate heat © 2015 Pearson Education, Inc.

50. HOMEOTHERM BODY TEMP Homeotherms reduce body temperature through evaporative cooling moisture evaporates from the skin and heat is lost panting and sweating accelerate evaporative cooling some animals wallow in water or wet mud © 2015 Pearson Education, Inc.

51. HOMEOTHERM BODY TEMP Small endotherms must eat almost constantly Small size means larger surface to volume ratio more heat is lost to the environment Heat loss is offset by increased metabolic rate small shrews eat about their wet body weight in food each day Size limit of about 2 g on endotherms some shrews and hummingbirds fall below this by undergoing torpor daily to reduce metabolic needs © 2015 Pearson Education, Inc.

52. FIGURE 7.21 © 2015 Pearson Education, Inc. 1 2 3 4 5 6 7 8 1000100100.1 Body mass (kg) 0.0101 Rat Mouse Rabbit Cat Sheep Horse Man Dog Flying squirrel Elephant Shrew Cactus mouse Kangaroo mouse Harvest mouse Mass specific oxygen consumption (liter O 2 /kg/hr)

53. HOMEOTHERM BODY TEMP Torpor – the dropping of the body temperature to approximately ambient temperature for part of a day diurnal animals – hummingbirds – enter torpor at night nocturnal animals – bats – enter torpor during the day When the animal becomes active again, body temperature quickly rises back to normal © 2015 Pearson Education, Inc.

54. HOMEOTHERM BODY TEMP Hibernation – the dropping of the body temperature to near ambient temperature for a long period of time during the winter a state of controlled hypothermia heart rate, respiration, total metabolism drop body temperature goes below 10  C animal goes into acidosis CO 2 levels in the blood increase, blood pH decreases – drops shivering threshold Animals rewarm using only metabolic heat © 2015 Pearson Education, Inc.

55. HOMEOTHERM BODY TEMP What about bears, do they hibernate? Black bears, grizzly bears, and female polar bears do not hibernate Enter winter sleep body temperature drops only a few degrees do not eat, drink, urinate or defecate females give birth and nurse young at this time are easily roused Instead of excreting urea in urine, the bear recycles it. © 2015 Pearson Education, Inc.

56. HOMEOTHERM BODY TEMP A countercurrent heat exchange system requires blood vessels that flow in opposite directions in close proximity can conserve heat or cool depending on the configuration © 2015 Pearson Education, Inc.

57. FIGURE 7.23A © 2015 Pearson Education, Inc. Artery 37  32  28  16  18  21  Vein From cold tail, flipper or foot (a) 24  Blood flow without countercurrent heat exchange Toward cold tail, flipper or foot Temperature of blood declines continuously as heat is lost to the surrounding environment as it flows into and out of the limb.

58. FIGURE 7.23B © 2015 Pearson Education, Inc. (b) 15  Artery Blood flow with countercurrent heat exchange 37  29  36  28  21  Vein 22  With countercurrent exchange, the close proximity of the artery and vein allows heat to be transferred from the warm arterial blood to the colder venous blood as it travels back into the body interior, conserving heat.

59. FIGURE 7.23B © 2015 Pearson Education, Inc. (b) 15  Artery Blood flow with countercurrent heat exchange 37  29  36  28  21  Vein 22  With countercurrent exchange, the close proximity of the artery and vein allows heat to be transferred from the warm arterial blood to the colder venous blood as it travels back into the body interior, conserving heat.

60. FIGURE 7.23C © 2015 Pearson Education, Inc. 35  30  20  10  33  27  18  99 Vein Artery (c)

61. FIGURE 7.24 © 2015 Pearson Education, Inc. Cooled venous blood Cooled arterial blood Brain Evaporation Warmed arterial blood

62. HOMEOTHERM BODY TEMP Bergmann’s Rule – for endotherms, body size for a species tends to increase with decreasing mean annual temperature This produces a cline in body size concordant with latitude (spatial) Similar changes in body size have also been seen over time (temporal) © 2015 Pearson Education, Inc.

63. MAINTAINING BODY TEMP Ectotherm / Poikilotherm Benefits lower metabolic rate requires fewer calories per gram of body weight (less food) can allocate more energy to producing biomass than to metabolism can reduce or curtail metabolic activity when food or water is limited, or environmental conditions are extreme can live in environments where food and water are limited © 2015 Pearson Education, Inc.

64. MAINTAINING BODY TEMP Ectotherm/Poikilotherm Costs temperature of the environment determines activity maximum body size is constrained because heat is absorbed across the body surface surface/volume ratio becomes to low for heat to warm the entire body mass larger ectotherms can live in only in warmer environments © 2015 Pearson Education, Inc.

65. MAINTAINING BODY TEMP Endotherm/homeotherm Benefits homeotherms can remain active even if environmental temperature varies maximum body size is not constrained because heat is generated internally large endotherms can live in cool environments © 2015 Pearson Education, Inc.

66. MAINTAINING BODY TEMP Endotherm/Homeotherm Costs higher metabolic rate requires more calories per gram of body weight (more food) small endotherms must eat almost constantly – why? usually allocate more energy to metabolism than to producing biomass producing insulation © 2015 Pearson Education, Inc.