1 / 28

by Giovanni Casotti Department of Biology West Chester University, West Chester, PA

NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE. A Presentation to Accompany the Case Study:. Living on the Edge. by Giovanni Casotti Department of Biology West Chester University, West Chester, PA. A Day in the Life of a Hummingbird. Extreme environments: Osmoregulation. Strategies.

marthareed
Download Presentation

by Giovanni Casotti Department of Biology West Chester University, West Chester, PA

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE A Presentation to Accompany the Case Study: Living on the Edge by Giovanni Casotti Department of Biology West Chester University, West Chester, PA A Day in the Life of a Hummingbird

  2. Extreme environments: Osmoregulation

  3. Strategies Osmoconformers • Plasma > 290 mOsm Osmoregulators • Plasma ~ 290 mOsm

  4. Aquatic environment Euryhaline • Eustarine species Stenohaline • Other species

  5. Aquatic environment Ionoconformer Ionoregulator

  6. Aquatic environment FW problems • High amount of water intake • Loss of body ions Problem Solution

  7. Aquatic environment SW problems • High amount of ion intake • Loss of body water Problem Solution

  8. Evolution onto land Problem - dehydration • Evolve renal morphology (birds and mammals) thus altering function Birds • Role of the cloaca Mammals • Efficient kidneys

  9. Renal morphology Fishes, amphibians, reptiles • Nephron at right angle to collecting duct

  10. Renal morphology Birds and mammals • Development of the loop of Henleparallel to collecting duct

  11. Renal function Renal processes • Filtration • Reabsorption • Secretion

  12. Countercurrent multiplier Important points • Water movement if passive – osmosis • Water movement depends on ion gradient • Development of a concentration gradient in the medulla • The role of antidiuretic hormone • The role of the vasa recta

  13. Countercurrent multiplier

  14. U/P ratios VertebrateRatio Fish 0.1-1.0 Amphibians 0.1-1.0 Reptiles 0.1-1.0 Birds 0.1-2.5 Mammals 0.2-26.0

  15. Avian cloaca Temporary storage Reabsorb Na+, K+, Cl-, H2O

  16. Case study Hummingbirds/Sunbirds • A unique animal on the edge of survival • Watch the hummingbird video

  17. Hummingbirds Unique challenges • Dilute (up to 3 - 6 times body mass/day) or a concentrated diet. Can they dehydrate?

  18. Nectar variability The influence of nectar sucrose and activity of sucrase.

  19. Case Study Questions • 1. Do floral nectar concentrations vary throughout the day. Why do you think that hummingbirds are active feeders first thing in the morning?  • 2. What are some of the daily osmotic challenges faced by sunbirds? How do they cope physiologically with low and high concentrations of nectar? • 3. Why don’t you see hummingbirds feed during the hottest part of the day?

  20. Hummingbirds Unique challenges • High rate of water fluxthat is variable

  21. Hummingbirds Unique challenges • High excretory rate (up to 3 - 6 times its body mass/day)

  22. Hummingbirds Unique challenges • High metabolic rate Allen hummingbird Anna hummingbird House wren Widow bird Swallow Shrews Mice

  23. Hummingbirds Unique solutions • Modified kidneys with virtually no medulla • Undergo Torpor

  24. Case Study Question • 4. From the material presented in this lecture, explain how the mammal nephron produces a concentrated urine. In your answer explain how the countercurrent multiplier mechanism operates, the importance of the design of the thin descending and thick ascending limb of Henle, and the length of the loop of Henle.

  25. Case Study Read the paper on hummingbird renal morphology Question • 5. Casotti et al. (1998) discusses 3 renal adaptations that enable Anna’s hummingbird to survive on a high water flux, low ion diet. What are they and how do they operate?

  26. Torpor

  27. Torpor

  28. Case Study Reading the article on torpor in the Rufous hummingbird Questions • 6. What is torpor and why is it an important physiological adaptation for survival? • 7. How much of a decrease is there in O2 consumption between normothermy and torpor? How long does torpor typically last?

More Related