1. Fundamentals of Biology As a universal solvent, water provides the medium in which all other molecules dissolve and interact in the process of life Besides water, most of the chemicals that make life possible are organic compounds; compounds that contain carbon, hydrogen, and oxygen Organic compounds are high-energy molecules

2. Fundamentals of Biology Most organic molecules belong to one of four main groups: – Carbohydrates (storage and structural sugars) – Proteins (enzymes, hormones, structure, signaling) – Lipids (energy storage, buoyancy, water repulsion) – Nucleic acids (store and transmit genetic info)

3. The Fuel of Life The molecules that make up living things interact in many complex chemical systems Most importantly, organisms have to capture, store and use energy (in the form of ATP) Two main pathways to process energy: – Photosynthesis – Respiration

4. Photosynthesis Most organisms ultimately get their energy from the sun In photosynthesis, algae, plants and other photosynthetic organisms capture the sun’s energy and use it to make glucose, a simple sugar, which is stored, utilized, and/or converted into other organic compounds – Such organisms are called autotrophs

5. Photosynthesis Solar energy is captured by pigments such as chlorophyll and is converted into chemical energy (ATP) which is then used to make glucose out of CO 2 and H 2 O; releasing O 2 as a by-product

6. Respiration Organisms that cannot photosynthesize and produce their own food are called heterotrophs Heterotrophs must obtain energy from organic matter that was produced by autotrophs Both autotrophs and heterotrophs perform respiration to utilize the energy stored in organic compounds by photosynthesis

7. Respiration In respiration, sugars are broken down using oxygen, giving off CO 2 and water as a result All living organisms respire!

8. Respiration and Photosynthesis Respiration: ATP C 6 H 12 O 6 + 6O 2  6CO 2 + 6 H 2 O Photosynthesis light energy 6CO 2 + 6 H 2 O  C 6 H 12 O 6 + 6O 2 Chemosynthesis chemical energy 6CO 2 + 6 H 2 O  C 6 H 12 O 6 + 6O 2

9. Levels of Ecological Organization Populations Communities Ecosystems

10. Levels of Ecological Organization: Population A group of individuals of the same species living together in one area; interbreeding

11. Levels of Ecological Organization: Population A group of individuals of the same species living together in one area; interbreeding

12. Levels of Ecological Organization: Community Populations of different species living together in one area; naturally-occurring

13. Levels of Ecological Organization: Ecosystem Communities and non-living components of the environment in which they interact

14. Challenges of Life in the Sea Many adaptations of marine organisms have to do with maintaining homeostasis Homeostasis: regulation of an organism’s internal environment to maintain a stable, constant condition (regardless of external conditions) – Salinity – Temperature

15. Salinity Many enzymes and other organic molecules are extremely sensitive to the concentration of ions in solution Whenever the internal composition of a cell differs from that on the outside, substances tend to move in or out of the cell by diffusion Diffusion – process by which molecules move from areas of high to areas of low concentration

16. Salinity Osmosis is the diffusion of water from areas of high to areas of low concentration If there is more dissolved material, and therefore less water inside a cell than outside, water will move into the cell by way of osmosis When the outside water is more concentrated than the cell, the cell loses water by osmosis to the external environment

17. a) More water outside of cell than inside: water moves into cell b) Same water outside of cell as inside: no movement of water c) Less water outside of cell than inside: water moves out of cell

18. Red blood cell

19. HypotonicHypertonicIsotonic More solutes; less water Equal solutes and water Fewer solutes; more water

20. Hypertonic More solutes; less water Isotonic Equal solutes and water Hypotonic Fewer solutes; more water

21. Hypertonic More solutes; less water Cell in a Hypertonic Solution During osmosis, water moves from regions of high to regions of low concentration Water molecules move from the red blood cell into the hypertonic solution The movement of water from the red blood cell causes the cell to shrivel and shrink.

22. Cell in an Isotonic Solution Since the number of solutes in the cell is equal to the number of solutes in the solution, there is no net movement of water from or into the red blood cell. Isotonic Equal solutes and water

23. Hypotonic Fewer solutes; more water Cell in a Hypotonic Solution Water molecules move from the hypotonic solution into the red blood cell. The movement of water into the red blood cell causes the cell to swell and eventually burst. During osmosis, water moves from regions of high to regions of low concentration.

24. Images : Copyright © The McGraw-Hill Companies, Inc. HypertonicIsotonicHypotonic

25. Regulation of salt and water balance Generally speaking, marine organisms live in a liquid medium that is more concentrated in ions than that of their internal environments Some marine organisms regulate their salt and water balance by doing nothing at all; their internal concentrations change as the salinity of water changes – Such organisms are osmoconformers – Most can live only within a narrow range of salinity

26. Osmoconformers SodiumMagnesiumCalciumPotassiumChloride Seawater 478.354.510.510.1558.4 Jellyfish 474531010.7580 Polychaete 47654.610.5 557 Sea urchin 47453.510.610.1557 Mussel 47452.611.912553 Squid 45655.410.622.2578 Isopod 56620.234.913.3629 Crab 48844.113.612.4554 Lobster 5419.311.97.8552 Hagfish 537185.99.1542 Adapted from Potts and Parry 1964 as cited by J. Levinton 2009

27. Osmoregulators Most osmoregulators, however, maintain blood concentrations that are different from that of the surrounding seawater Most marine fish have body fluids considerably more dilute than seawater, and so are constantly losing water by osmosis To osmoregulate, marine fish drink seawater to replace the water lost by osmosis, and excrete excess salts actively through the gills

28. Osmoregulation in marine fish

29. Osmoregulation Freshwater fish have the opposite problem; their blood has a higher concentration of salt than does the surrounding water, and are constantly taking in water by osmosis To osmoregulate, freshwater fish do not drink and absorb salt through their gills; they also produce large volumes of dilute urine to remove excess water

30. Osmoregulation in freshwater fish

31. Osmoconformers vs. Osmoregulators Sharks are a special case of osmoregulators – Sharks osmoregulate by changing their internal concentrations of solutes to match that of their surroundings – It doesn’t matter if there are the same dissolved chemicals inside & out, so long as the total amount of dissolved material is the same Sharks or the amount of urea in their blood

32. Osmoregulation in marine birds & reptiles Marine birds and reptiles (and some plants) have specialized cells or glands to rid themselves of excess salt

33. Salt glands in action (Southern fulmar)!

34. Osmoregulation Marine mammals osmoregulate by not drinking seawater and excreting highly concentrated urine

35. Harbor seal kidney

36. Temperature Organisms are greatly affected by temperature The rate of metabolic, chemical reactions increase with increasing temperature, and slow down dramatically as it gets colder At extremely high temperatures, proteins (including enzymes) denature and cease to function At extremely low temperatures, tremendous heat loss can occur, making it difficult to maintain a constant body temperature

37. Temperature Most marine organisms are adapted to live within a particular temperature range All organisms generate metabolic heat, but in most organisms this heat is quickly lost to their surrounding environment; such organisms are ectotherms, cold-blooded organisms that are as warm or as cold as their surroundings

38. Temperature Other marine organisms retain their metabolic heat such that their internal body temperatures are higher than that of their surroundings; such organisms are endotherms or warm-blooded Endotherms include all mammals, birds, and some large fishes including tuna and sharks, as well as the leatherback sea turtle!

39. Endotherms in action!

40. Now to confuse you… Another way to categorize organisms is by whether or not they can maintain a constant internal body temperature The body temperature of poikilotherms changes with the temperature of the external environment – All ectotherms are poikilotherms – Can make ectotherms sluggish if the water is colder than they are used to animals.nationalgeographic.com

41. Poikilotherms vs. Homeotherms Endothermic tunas and sharks are also poikilothermic – Although they retain metabolic heat generated by their large muscles and are warmer than the surrounding water, their internal temperature still goes up and down as the water temperature changes Mammals and birds are able to maintain their internal temperatures even when external temperatures vary; they are homeotherms

42. Endothermic homeotherms Requires a tremendous amount of energy To reduce the energy cost of maintaining a constant body temperature, homeotherms are insulated with feathers, hair and/or blubber

43. Thermoregulation Organisms have evolved mechanisms (adaptations) to regulate their body temperature and reduce heat loss to their environment – Changes in surface area to volume ratio – Presence of “antifreeze” compounds – Increase in muscular activity (“shivering”) – Adjusting blood flow to (or away from) skin – Adjusting amount of insulation – Orienting body towards sun

44. Thermoregulation in action! http://dive.scubadiving.com/d2d_archive/read.php?f=1&t=920399&a=2&

45. Counter-current heat exchange Some endodermic birds and mammals regulate their internal body temperature by way of a counter-current heat exchange system – Warm blood pumped from within the body is used to warm the cooler blood returning from the extremities – Ingenious; blood leaving the warm interior loses its heat to returning vessels just before they enter the (cooler) extremities warming returning blood!

46. Countercurrent Heat Exchange

47. As ‘arterial’ blood leaves the body and enters the extremity, it transfers heat to returning ‘venous’ blood, which allows warm blood to re-enter the body, and reduces the loss of heat to the surrounding environment

48. Common dolphin dorsal fin

50. artery vein

51. Challenges to Life – Salt Marshes Organisms living in salt marshes are also subject to extreme ranges in temperature, exposure/submersion, and salinity Characterized by specialized plants (Spartina) capable of surviving in (and then out of) saltwater http://en.wikipedia.org/wiki/File:Bride-Brook-Salt-Marsh-s.jpg

52. Challenges to Life – Tidal pools Organisms existing in tidal pools are subject to extreme swings in moisture, temperature and salinity Illustration from "Discover Nature at the Seashore", Lawlor 1992 http://www.nsrwa.org/Page.85.html

53. Life’s a Beach… or not As benign and peaceful as sandy beaches look, they are among the most hostile environments for small organisms Sand grains are abrasive and many organisms must have protective coatings and/or be able to burrow below the surface for protection In fact, very few organisms survive in wave- swept sandy beaches www.stripersonline.com/surftalkshowthread.php?t=417951