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NABS Video?

NABS Video?. Lec 1b: Life in Water - Adaptations. I. Diversity in Freshwater II. Adaptations to Life in Freshwater A. Respiration B. Flow C. Osmotic balance D. Life history E. Motion F. Feeding & Food Collection. 1. I. Diversity in Freshwaters. 2. A. Low compared to Marine

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NABS Video?

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  1. NABS Video?

  2. Lec 1b: Life in Water - Adaptations I. Diversity in Freshwater II. Adaptations to Life in Freshwater A. Respiration B. Flow C. Osmotic balance D. Life history E. Motion F. Feeding & Food Collection 1

  3. I. Diversity in Freshwaters 2 A. Low compared to Marine (41 vs. 56 phyla; 15 marine only; ID?) B. Possible reasons…. 1. Osmotic incompatibility 2. Ephemeral nature of FW systems 3. Low volume 4. Physically discontinuous -What taxa can overcome this? (metapop’n) -How do humans ‘help’? 5. Dynamic (Chem. & Phys) -actually increases diversity…. 6. Exceptions: Non-glacial lake endemics

  4. Insect Diversity Ephemeroptera (Mayfly) Odonata (Dragon/Damsel) Plecoptera (Stonefly) Hemiptera (True Bug) Megaloptera (Hellgrammite) Trichoptera (Caddisfly) Coleoptera (Beatle) Diptera (Fly) 3

  5. Orders of Insects with Aquatic Life Stages Order Aquatic Stage # Aquatic Spp #Non-Aquatic Spp Collembola All 25 300 Ephemeroptera Nymphs 625 0 Odonata Nymphs 425 0 Orthoptera All 5 1000 Plecoptera Nymphs 425 0 Hemiptera All 400 4600 Neuroptera Larvae 5 300 Megaloptera Larvae 40 0 Coleoptera All 1000 30000 Trichoptera Larvae 1000 0* Lepidoptera Larvae 50 10000 Diptera Larvae 10%? 17000 Hymenoptera Larvae 0.5%? 17000 4

  6. Fish Diversity Fishes are the most numerous of all vertebrates Amphibians 2500 spp Reptiles 6000 Birds 8600 Mammals 4500 Fish 25000 (Why?) Fish Distributions • 58% are in marine (0.58*25000=14,500spp) • (15,482 marine species as of Nov.2004) • 41% are in freshwater • 1% occupy both 5

  7. II. Adaptations to Life in Freshwater A. Respiration • Breathing air vs. water • Tidal process in air, ventilation in water • Air Water Contrasts: • AirWater • High [O2] Low [O2] • Light (0.013 kg/l) Heavy (1 kg/l) 6

  8. Increasing exposure to DO can be active or passive 7

  9. Obtain O2 directly from air: Snorkels: -direct: rat tailed maggot -indirect: use of aquatic plants -sharp spiracles thrust into plant arenchyma (Donacia) Tubes: Mosquitoes, Ranatra -change from caudal tube in larvae to thoracic horns in pupae Both make use of hydrophilic and hydrophobic surfaces PROBLEM: not transportable; need to 'grab' some air and keep it in contact w/ spiracles 8

  10. Direct diffusion through the body surface if small (e.g. Diptera) Why not possible for larger organisms? Tracheal gill(Ephemeroptera, Plecoptera, Odonata, Trichoptera) -operates best in moving water. Why? -anal gills in Anisoptera -filamentous gills in Trichoptera, Neuroptera -can adapt to changes in DO by ventilation -Mayfly gills nervous and muscular connections -Dragonflies expand and contract rectal chamber -Damselflies fan caudal lamellae -Stoneflies, caddisflies do 'pushups', or undulate -Hexagenia will undulate in their burrows to improve water flow 9

  11. Ephemeroptera (Mayflies) Plecoptera (Stoneflies) Questions: Does the surface area of the gills have anything to do with the DO concentration of the habitat? What could be some mitigating factors or adaptations? 10

  12. II. Adaptations to Life in Freshwater B. Flow(why no/little plankton in lotic systems?) 11 1. Morphology (which are general?) a. Body flattening b. Streamlined or fusiform body c. Reduction of projecting structures (aids swimming) d. Anchoring devices: suckers, hooks, silk e. Small size f. Ballast 2. Behavior a. Avoid current b. Migration (incl. drift) c. Emergence 3. Distinct communities (Riffle vs. pools) -Flow adapted taxa: 'Rheophilic' and 'Torteniculous' taxa Belphariceridae

  13. Laminar flow • Turbulent flow 12 12

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  15. Salt and freshwaters present different problems II. Adaptations to Life in Freshwater C. Osmotic balance One of two options…. 14

  16. II. Adaptations to Life in Freshwater D. Life History (Does the habitat meet all of the needs for metabolism, food, reproduction?) 1. Migration (insects, fishes) 2. Partially aquatic (amphibians, insects) 3. Resting stages in temporary habitats (crustaceans, molluscs) 15

  17. II. Adaptations to Life in Freshwater E. Motion 1. Passive-Floating (Problem: Most organisms are more dense than water 16

  18. II. Adaptations to Life in Freshwater E. Motion 1. Passive-Floating Stokes Law - applies to very small spherical objects • Sinking velocity of a spherical particle follows Stoke’s Law : • g = gravitational acceleration (m / s2) • η = coefficient of viscosity of the medium (kg/m/s) • densm = density of fluid • densp = density of particle • r = radius of the particle 17

  19. 18 Phytoplankton Macrophytes

  20. II. Adaptations to Life in Freshwater E. Motion 2. Swimming -Both push against water and reduce drag a. Effect of gravity is less than in air - fish can “float” - leading to free movement through a 3 dimensional environment b. Most muscle can be devoted to movement rather than to offsetting gravitational pull c. High density increases resistance; and hence increases energetic costs -musculature must be devoted toward forward movement d. Streamlining will reduce resistance of dense water e. Surface area of 'propelling' surface (vs. a bird; better yet think about penguin vs. flying birds) 19

  21. Jordan’s Rule: Links between fish morphology, water temperature, and density? • Within species, individuals will have more vertebrae or body segments when reared at colder temps • 2. More vertebrae in fish at higher latitudes • 3. Water temp ~ viscosity • 4. How to cope? Greater flexion, more vertebrae • 5. Check Re eqn: get longer, reduce effect of viscosity 20

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  23. Caddisfly net F. Feeding Blackfly larvae Daphnia ‘leg’ 21 22

  24. F. Feeding Cladoceran Copepod 23

  25. F. Feeding 23 24

  26. Lab Consider some of these adaptations when examining specimens Infer aspects of habitat and strategies for living in water from organism morphology

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