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  1. 1. Anna Fabrizio 3/9/10 University of Washington School of Aquatic and Fisheries Sciences Chemotaxis and foraging behavior in Octopus rubescens
  2. 2. Octopus physiology <ul><li>octopuses are known to have well developed vision, often used for hunting </li></ul><ul><li>many octopuses live in habitats where vision is compromised </li></ul><ul><li>many octopuses prey on organisms that don’t move </li></ul><ul><li>octopus suckers are used for sensing “taste” </li></ul><ul><ul><li>most sensitive at the tips of arms </li></ul></ul>
  3. 3. Octopus foraging behaviors <ul><li>2 primary foraging behaviors: </li></ul><ul><ul><li>Poke/grope </li></ul></ul><ul><ul><li>Web-over </li></ul></ul><ul><li>Both are primarily tactile in nature, but dependent on visual range </li></ul>(Forsythe and Hanlon, 1995) Web-over Web-over Web-over Web-over
  4. 4. Octopus chemotaxis <ul><li>little research done on distance chemotaxis in octopuses </li></ul><ul><li>Chase and Wells (1986) </li></ul><ul><ul><li>Blind octopuses responded to and were able to sense the general direction of chemicals in the water </li></ul></ul><ul><li>Lee (1992) </li></ul><ul><ul><li>Octopuses in Y-maze responded to specific chemical direction </li></ul></ul><ul><li>research has been done on tactile/taste discrimination by octopuses (Wells 1962) </li></ul>
  5. 5. Objective <ul><li>to expand on previous chemotaxis studies by analyzing octopus reaction to live prey </li></ul><ul><ul><li>Octopus rubescens has not been used for chemotaxis studies in the past </li></ul></ul>
  6. 6. Behavioral experiments Experimental tank set-up T-wall boxes barrier wall
  7. 7. Behavioral experiments
  8. 8. Results <ul><li>19 trials performed: 8 blind, 11 visual </li></ul><ul><li>1 blind trial resulted in a choice (crab) </li></ul><ul><li>6 visual trials resulted in a choice </li></ul><ul><ul><li>all chose the crab </li></ul></ul><ul><li>Behavior observations </li></ul><ul><ul><li>more response to crabs during visual trials </li></ul></ul><ul><ul><ul><li>color change, active motion </li></ul></ul></ul>
  9. 9. What does this mean? <ul><li>Can we confidently determine that octopuses CAN use distance chemotaxis from previous studies done with chemicals alone? </li></ul><ul><ul><li>Natural foraging behaviors show little evidence for the use of distance chemotaxis </li></ul></ul><ul><ul><ul><li>But what about circumstances that compromise vision? </li></ul></ul></ul>
  10. 10. Stressed out crabs <ul><li>During trials, crabs also exhibited different kinds of behavior </li></ul><ul><ul><li>when crabs could see the octopus, they held very still but were obviously in distress </li></ul></ul><ul><li>Do octopuses respond more frequently to stressed crabs than non-stressed crabs? </li></ul><ul><ul><li>Is there a physiological difference between stressed/non-stressed crabs? </li></ul></ul>
  11. 11. Prey analysis – Hemigrapsus oregonensis <ul><li>Purpose: analyze shore crab RNA/protein to see if they express something that octopuses would respond to </li></ul><ul><li>Techniques: </li></ul><ul><ul><li>SDS/PAGE </li></ul></ul><ul><ul><li>PCR </li></ul></ul><ul><li>Specifically looking at stressed vs non-stressed </li></ul><ul><ul><li>stressed, immersed crabs excrete excessive ammonia, waste, carbon dioxide </li></ul></ul>
  12. 12. Procedure
  13. 13. Protein analysis <ul><li>protein fixation and extraction from gill tissues </li></ul><ul><li>SDS-PAGE gel </li></ul>C2 C3 C4 C5 C6 S1 S2 S3 S4 S5 S6
  14. 14. Results Genetic analysis <ul><li>RNA fixation and extraction from gill tissues </li></ul><ul><li>reverse transcription -> cDNA </li></ul><ul><li>4 primers, 3 genes – Carcinus maenas : </li></ul><ul><ul><li>CHH and CHH precursor 6: hormone expressed under stress </li></ul></ul><ul><ul><li>Metallothionein: cysteine-rich protein that helps reduce oxidative stress </li></ul></ul><ul><ul><li>Na+/K+ - ATPase: enzyme that helps regulate ammonia excretion </li></ul></ul>
  15. 15. Genetic analysis
  16. 16. <ul><li>further study into the significance of stress on prey and the ability of octopuses to find them </li></ul><ul><li>more extensive research on distance chemotaxis with live prey </li></ul>Future possibilities
  17. 17. Acknowledgments Steven Roberts, Sam White, Mackenzie Gavery Tim Carpenter, Kathryn Kegel - Roberts lab - Seattle Aquarium