BIOL 4120: Principles of Ecology Lecture 7: Animal adaptations to the Environment

1. BIOL 4120: Principles of Ecology Lecture 7: Animal adaptations to the Environment Dafeng Hui Office: Harned Hall 320 Phone: 963-5777 Email: dhui@tnstate.edu

2. Topics 7.1 Animals have various ways to acquire energy and nutrients 7.2 Animals have various nutritional needs 7.3 Animal require oxygen to release energy contained in food 7.4 Regulation of internal conditions involves homeostasis and feedback 7.5 Animals have different methods of maintaining their body temperatures 7.6 Poikilotherms depend on environmental temperatures 7.7 Homeotherms escape the thermal restraints of the environment 7.8 Endothermy and Ectothermy involve trade-offs 7.9 Heterotherms take on characteristics of ectotherms and endotherms 7.10 Torpor helps some animals conserve energy 7.11 Some animals use unique physiological means for thermal balance 7.12 Maintenance of water balance 7.13 Biological clocks influence animal activity

3. Chapter 7 Animal Adaptations to the Environment • Animals are heterotrophs and derive their energy and most nutrients from consuming organic compounds contained in other plants and animals • Key processes common to all animals • Acquire and digest food • Absorb oxygen • Maintain body temperature and water balance • Adapt to light and temperature variations • Animals encounter different constraints in aquatic versus terrestrial environments

4. 7.1 Animals have various ways of acquiring energy and nutrients Energy sources for plants and animals • Three Feeding Methods of Heterotrophs: • Herbivores: Feed on plants. • Carnivores: Feed on animal flesh. • Omnivores: Feed on both plants and animals • Detritivores: Feed on non-living organic matter (earthworm, dung beetle).

5. Mouthparts reflect how organisms obtain their food. Animals have various ways of acquiring energy and nutrients

6. Herbivores • Grazers (cattle, dear, sheep, grasshopper) • Leafy material (Ruminants chew the cud; Non ruminants are less efficient) • High in cellulose and some lignin (C:N ratio) • Use specialized microorganisms in gut to help digest the difficult carbohydrate molecules in ruman or cecum or redigestion (Fermentation) • Microorganisms produce proteins, lipids etc • Browsers • Woody material (Termites) • High in lignin and cellulose • Use specialized microorganisms in gut to help digest the difficult carbohydrate molecules • Microorganisms produce proteins, lipids etc • Granivores (birds) • Seeds • Crop with specialized enzymes • Gizzard for grinding • Frugivores (monkey etc.) • Fruit

7. Carnivores • First level feed directly on herbivores • No cellulose • Rapid digestion and easy assimilation • Hunting is energy consuming • Second level feed on first level carnivores • Omnivores • Food eating habits vary with season, life cycle and their sizes • Fox • Preferential carnivore • Insects, small mammals and birds • but eats berries, fruit, grass • Bear • Preferential herbivore • Buds, leaves, berries, fruit, etc • Supplemented by insects, fish and small to medium mammals

8. Red Fox is an example of an omnivore

9. 7.2 Animals have various nutritional needs • Animals need amino acids and specific minerals such as sodium, calcium, magnesium, etc • High quality and quantity of plants are very important to animal survival • Herbivores show certain preference on high N plants (Taste and odor) • Deficiency in minerals influences distribution, behavior, and physiology of animals • Sodium can be hard to obtain and can be a problem • Kangaroos, Rabbits in Australia • Overgrazing of sodium rich plants can cause population collapse (plants died) • Elephants • See preference for sodium rich water hole in Wankie National Park, Zimbabwe • Dear: eating mineral-rich soil in spring • High potassium in spring vegetation may cause calcium, magnesium deficiency in goats, cattle and sheep (influence hormone balance) • Nutrient conditions influence growth and reproduction.

10. Deer need lots of calcium, phosphorus and protein to grow antlers, which are needed for reproductive success • Deficiency results in stunted antlers

11. 7.3 Animals require oxygen • Energy from organic compounds in the food they eat • Release energy primarily through aerobic respiration • O2 is required (could be an issue for aquatic animals) • Methods to acquire O2 • Body surface: insects, tracheal tubes • Lungs: mammals, birds, reptiles • Lung and air sacs: birds • Lungs: whales and sharks • Gills: Fish

12. Respiration systems Animals need to use aerobic respiration • Therefore need to have excellent oxygen uptake system • Small animals • Diffusion • Insects • Diffusion and spiracles • Amphibians • Vascularised skin • Simple lungs • Mammals • Lungs • Birds • Lungs • Anterior and posterior air sacs • Fish • Gills • Aquatic mammals • Lungs • Special haemoglobin oxygen storage systems O2 countercurrent exchange

13. BIOL 4120: Principles of Ecology Lecture 7: Animal adaptations to the Environment Dafeng Hui Office: Harned Hall 320 Phone: 963-5777 Email: dhui@tnstate.edu

14. 7.4 Regulation of internal conditions involves homeostasis and feedback Homeostasis: The maintenance of a relatively constant internal environment in a varying external environment. Homeostasis depends on negative feedback Negative feedback: when a system deviates from the normal or desired state, mechanisms function to restore the system back to that state. Example: room temperature setting

15. Homeostasis • To stay alive, animals need to keep their body within certain limits • Temperature • Water balance • pH • Salt balance • Feedback systems to help to keep within specific limits • Outside limits – • Dehydration • Heat shock • Salt imbalance • Death

16. Negative feedback (thermoregulation)

17. Animals exchange energy with their surrounding environment • Body structure influences the T exchange • Temperature (Tb, Ts, Ta) • Tb<->Ts conduction • Boundary layer (a thin layer of air surround the body) • Core temperature Tb • Surface temperature Ts • Ears • Fingers • Toes • Ts<->Ta: conduction, convection, radiation, evaporation • Insulation (air, body covering) influences energy exchanges

18. 7.5 Animals have different methods of maintaining their body temperatures Three groups of animals • Endothermy resulting in homeothermy • Use of internal heat source (metabolically) • Mammals and birds • Maintain a fairly constant temperature (warm-blooded) • Ectothermy resulting in poikilothermy • Use of external heat sources • Reptiles, amphibians, fish, insects and invertebrates • Results in a variable body temperature (cold-blooded) • Heterotherm • Uses both endothermy and ectothermy • Bats, bees and hummingbirds • Depends on environmental situations and metabolic needs.

19. As the temperature increases, so does the metabolic rate Therefore these animals are more active during the day Every 10oC doubles metabolic rate Naturally low metabolic rate and high conductivity Activities also control temperature Upper and lower limits vary Lizards and snakes have a 5oC Amphibians have a 10oC 7.6 Poikilotherms depend on environmental temperatures Operative T range: range of body T at which poikilotherms can carry out their daily activities (next slide).

20. During the day, the snake can maintain a fairly constant temperature by adjusting it’s environment (bask in sun to raise T, seek shade to cool, submerge in water etc) • During the night, it has few options • Temperature drops 10-15 degrees • Become torpid (slow moving) • Restricted by environment • Limited to Maximum size due to need for surface area to gather heat • No minimum size

21. Poikilotherms in water • No insulation • Match of body temperature to water temperature • Water temperature normally only changes slowly with season • Poikilotherms can adjust slowly to a wide range of temperatures than land poikilotherms (acclimation) • Stressed by rapid temperature changes

22. 7.7 Homeotherms escape the thermal restraints of the environment Homeotherms can escape the thermal restraints of the environments, thus can exploit a wide range of thermal environments But needs energy to maintain relative constant T Therefore homeotherms use large amounts of glucose etc to maintain temperature (aerobic respiration) O2 is consumed during respiration Rate of O2 consumption is used to measure metabolic rate

24. Resting metabolic rate and ambient temperature Thermoneutral zone: a range of environmental temperatures within which the metabolic rates are minimal. Critical T: lower and upper critical T

25. Homeotherms can escape the thermal constraints of the environments Ways to keep body warm: 1. Insulation to reduce the convection: fur, feather, or body fat Mammals: fur, change fur in the winter Fur can keep body heat in and the heat out Birds: feather Insects: a dense fur-like coat (moths, bees) 2. When insulation fails: shivering (a form of involuntary muscular activity that increase heat production. 3. Small mammals: burn brown fat (bats) without shivering. Ways to keep body Cool: 1. birds and mammals: evaporation of moisture from skin 2. mammals: sweat glands (horse, human), panting 3. birds: gular fluttering

26. 7.8 Endothermy and Ectothermy involve trade-offs New Scientist, 2009

27. 7.8 Endothermy and Ectothermy involve trade-offs Endotherms can survive in large range of T, why not all animals are endotherms? Endotherms Ectotherms Activity: under all environments limited to environmental T Energy: high low Food: most for respiration, less less for respiration to growth more to growth Limits on size: limit on minimum size limit on maximum size

28. Limited in size Warm-blooded animals: body mass (volume) produce heat, lost through surface area, the ratio of surface to volume is key factor too. Small animals have larger ratio and greater relative heat loss to environment, require higher mass-specific metabolic rate to maintain and consume more food energy per unit body weight. Too small Need too much energy to keep temperature stable 2 gm limit Shrew (Solex spp) eats own body weight in food every day to maintain temperature Cold-blooded animals absorb heat through surface, thus the surface area to volume is also a key factor. Large animals limited to warm areas.

29. Metabolic rate and body mass

30. Temporal heterotherms: species that sometimes regulate their body T and sometimes they do not. • Insects, bats, bees, hummingbirds • Adult insects can be ectothermic and endothermic: • T limits on flight: 30oC for take off, and no more than 40oC for flight • Need warm-up to take off: ectothermic • Flight: burn energy, endothermic 7.9 Heterotherms take on characteristics of ectotherms and endotherms

31. 7.10 Torpor helps some animals conserve energy • Torpor • Small homeothemic animals • Become heterothermic • Body temperature drops to ambient at night • Inactive • Bats, Some mice, kangaroos • Hibernation • Many poikilotherms and some mammals have winter torpor to save energy • Selective advantage when resources are few • Mammals • Heart rate, respiration fall • Temperature drops to ambient • Groundhogs, chipmonks • Not bears • No temperature change • Just long sleep with no eating, drinking, defecating or urinating • Females give birth and feed young in this period • Can wake up easily • Do not visit a bear cave in winter!

32. 7.11 Some animals use unique physiological means for thermal balance Storing body heat: Camel, oryx and some gazelles Body T change from 34oc to 41oC for camel (morning to afternoon) Reduce need for evaporative cooling and save water and energy Supercooling: many ectothermic animals of temperate and Arctic regions When the body T below freezing points without actually freezing The presence of certain solute (glycerol) in the body lower the freezing points Wood frog, grey tree frog, spring peeper Countercurrent heat exchange: to conserve heat in a cold environment and to cool vital part of body during heat stress.

33. Countcurrent heat exchange happens in homeotherms (porpoise, whale) as well as in certain poikilotherms (tuna, mackerel shark) To preserve heat in cold water, and get ride of heat in warm water To cool brain, reduce T by 2-3oC

34. 7.12 Maintenance of water balance • Terrestrial • Input • Drinking • Eating • Produced by metabolism (respiration) • Output – Need to control in extreme environments • Urine • Concentrated to avoid water loss • Feces • Evaporation • No sweat glands in some mammals • Breathing

35. What happens to ungulates in a hot dry climate like Africa No pants, no sweating to save water, store heat in body (T up to 46oC at daytime, release heat at night 36oC) Countcurrent heat exchange to lower head T Eat at nighttime, more water in plants Respiration to produce water

36. Maintenance of water balance • Aquatic • Freshwater (hyperosmotic, high salt in body) • Prevent excess uptake of water • Remove excess water • Retain salt in special cells (gills) • Large amounts of very dilute urine • Saltwater (hypoosmotic, low salt in body) • If salt concentration is higher than in body, dehydrate • Ion pumps, gill (fish) • Kidneys (eliminate salts, marine mammals) • Salt secreting glands in birds

37. Buoyancy aids aquatic organisms to stay afloat • Gas or swim bladder (most fish) • 5-10% body volume • Lungs in air-breathing animals • Replace heavy chemical ions in the body fluids with lighter ones • Squid (ammonium ions to replace sodium ions) • Shark, mackerels, bluefish: store lipids (less dense than seawater)

38. Aquatic animals need to move up and down in water Buoyancy aids Shark Large fatty liver Must swim to not sink Fish Gas bladder Used to move up and down Seal Blubber Can float on surface with air in lungs

39. 7.13 Biological clocks influence animal activity • Daily and seasonal light and dark cycles • Critical daylengths trigger seasonal responses • Activity rhythms of intertidal organisms follow tidal cycles

40. Animals react to changing light through internal biological clocks • Internal Biological Clocks have adaptive value • Used to change behavior: feeding, food storage, reproduction, migration. • Daily (Circadian rhythm): sleep, metabolic rate, temperature Predators must match their feeding activity with prey. Seasonal: food storage, migration

41. Seasonal Changes for male deer • Only needed during mating season • Can be damaged and need replacing

42. Squirrels start activity when the day starts, regardless of the season Critical daylengths trigger seasonal responses

43. Daylengths influence organisms activity • Critical daylength • Duration of light or dark reaches a certain proportion of the 24-hour day, it inhibits or promotes a photoperiodic response. • Normally 10-14 hours • Day-neutral organisms: not controlled by daylength • Short-day organisms: reproduction (or other activity) is stimulated by daylength shorter than critical daylength • Long-day organisms: ~longer~ • Diapause: a stage of arrested growth over winter in insects of the temperate regions controlled by photoperiod. • Requirement: 12-13 hours of light • A quarter-hour difference can determine diapause or not

44. Crabs from a tidal estuary retain timed activities in a fixed environment Color change (day and night) Activity (tides) Two clocks Tidal Solar Activity rhythms of intertidal organisms follow tidal cycles

45. The END

46. Circadian (24 hr) rhythm is very important to most living organisms • Timing measures • Light • Temperature • Moisture • Temperate zone • Light cycle • Arctic and subarctic zones • Temperature • Tropical and subtropical zones • Moisture

47. Water Movement in Aquatic Environment • Isomotic (isotonic): Body fluids and external fluid are at the same concentration. • Hypoosmotic (hypotonic): Body fluids are at a lower concentration of salt than the external environment. • Hyperosmotic (hypertonic): Body fluids are at a higher salt concentration than the external environment. (freshwater)

48. Fig. 5.4

50. Digestive systems are different for these different type of animals Stomach Caecum: Intestine Colon