1. Animals live in varied environments
   1. Freshwater: Lots of water, but little salt
   2. Seawater: Lots of water, but a lot of salt
   3. Land: Little water or salt
2. Animals in Freshwater
   1. Hyperosmotic
   2. Gain water by osmosis
   3. Lose ions by diffusion
   4. Shell, cuticles, scales
   5. Gain ions from food
3. Table 27.1
4. Fig 27.1 Water–salt relations in a freshwater animal
   1. Gills highly permeable / lots of ion exchange here !
   2. Make large amounts of dilute urine

5. Fig 27.7a Water–salt relations in freshwater teleost fish Image from Wikipedia

6. Fig 27.2 Ion exchanges mediated by active Na⁺ and Cl^– transport in the gill epithelium of freshwater teleost fish
   1. Absorb or actively transport ions into body
   2. Requires ATP
   3. Cl^– exchanged for HCO3
   4. Na+ exchanged for H+
   5. Fish have Cl^–cells in the gills
7. Animals in Saltwater
   1. Hyposmotic
   2. Gain ions from water
   3. Water loss
8. Table 27.3
9. Intracellular Ionic Regulation in Marine Invertebrates
   1. most are osmoconformers h
   2. active ionic regulation
   3. pelagic animals pump out sulfate ions for buoyancy
10. Hagfish Osmoregulation
    1. Marine and Stenohaline
    2. osmoconformers
    3. ionic regulators
11. Marine Teleosts

12. Fig 27.7b Water–salt relations in marine teleost fish Marine bony fish constantly loose water Obtain water in food and seawater Produce scant isosmotic urine Movement of water and ions in saltwater fish image from wikipedia

13. Salt balance in marine teleosts
14. Fish Gills: Box 27.2
    1. active transport of ions out of the gills.
    2. chloride cells excrete Cl, Na
    3. Direction of transport depends on water salinity
15. Marine air-breathing vertebrates
16. Marine Reptiles
17. Fig 27.8 Avian salt glands
18. Marine birds
19. Marine Mammals
    1. Do not have salt glands and do not drink seawater
    2. Obtain water from food and metabolism
    3. Modifications in nasal passages to reduce water loss
20. Kidneys produce urine hypertonic to sea water
    1. humans cannot drink seawater (lose more water to get rid of excess salt)
    2. whales can (but gain Na)
21. Fig. 27.9 Water–salt relations in a marine shark
    1. hyposmotic (1/3) but ONLY in regards to salts
    2. slightly hyperosmotic overall because they retain urea in their blood
    3. water enters by osmosis and in food, and is removed in urine.
    4. urea concentration is 100 times higher than that in mammals
22. Marine Elasmobranchs (sharks and rays) use trimethylamine oxide (TMAO)
23. Ionic regulation in marine sharks and rays
    1. rectal gland
24. Definitions
    1. stenohaline
    2. euryhaline
25. Figure 26.4 Salinity trends in an estuary
26. Figure 26.5 The responses of a resident osmotic regulator to variations in salinity in an estuary
    1. Brackish water animals are often euryhaline
    2. Most are iso-osmotic
    3. can tolerate considerable dilution.
    4. Active regulators are hyperosmotic to brackish water and better resist environmental fluctuations
27. Figure 27.10 Types of osmotic regulation
    1. Hyper-isosmotic:
    2. Hyper-hyposmotic:
28. Catadromic and Anadromic fish
29. Catadromic and Anadromic fish
30. Lamprey Osmoregulation
31. Lamprey osmoregulation, cont.
32. fresh-water elasmobranchs
33. OSMOREGULATION IN THE TERRESTRIAL ENVIRONMENT
34. Moist-skinned animals: Earthworms
35. Terrestrial Animals
    1. Surrounded by dry/desiccating environment
    2. Must limit water loss from evaporation
       1. Skin permeability
       2. Respiratory membranes
       3. Kidneys concentrate urine to decrease water
36. Amphibia
37. Frogs and other Amphibians
38. Amphibians
39. Desert Frogs
40. Figure 27.20 Arboreal frogs of the genus Phyllomedusa spread protective lipids secreted by integumentary glands over their skin surface
41. Arthropods: Insects and Arachnids
42. WATER BALANCE: GAINS AND LOSSES
43. WATER BALANCE: GAINS AND LOSSES
44. Water Loss in Insects and Arachnids
45. Water Loss in Insects and Arachnids
46. Water Gain in Insects and Arachnids
47. Water Gain in Insects and Arachnidsx
48. The kangaroo rat is a desert mammal that has quite different means of water conservation than humans.
    1. most of its water from carbohydrate metabolism.
    2. minimizes water loss from evaporation by aestivation during the heat of the day.
    3. generates concentrated urine
49. Figure 27.22 A kangaroo rat water budget

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