Lost?
Ask a Turtle:
Navigation and Migration in Loggerheads
by
Giovanni Casotti
Department of Biology
West Chester University, West Chester, PA
Terminology
Navigation
o Moving along a course
Migration
o Moving from one region
to another
Homing
o Returning back to a specific point
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Migration
Reproductive success
– Sockeye salmon (lifecycle migration and homing)
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Migration
Reproductive success
– Loggerhead turtles
− Elephant seals
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Case Study
Loggerhead turtles
1. How do hatchlings navigate to the ocean?
What dangers are faced by newly emerging
turtles hatchlings?
2. Once in the water, what mechanism do
hatchling turtles use to make their way
toward open ocean?
3. Once off the coast, juveniles make their way
to the North Atlantic Current (Gyre).
Describe this pathway.
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Migration
Food acquisition
– Humpback whales
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Navigation Strategies
Trail following
– Employed by
invertebrates only (ants)
Piloting
‒ Using landmarks to navigate
(pigeons)
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Navigation Strategies
Path integration
– Employed by invertebrates only (ants)
Return journey
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Navigation Strategies
Map and compass navigation
– Used by long distance migrators (whales and turtles)
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Terrestrial Animals
Compass navigation
– Using Earth’s magnetic field
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Case Study
Watch the video on turtle navigation:
http://www.youtube.com/watch?v=LbiBXRtiVrg
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Magnetite Receptors
Located in beaks of birds
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Magnetite Receptors
2 possible mechanisms of action
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Case Study
Question
4. How do hatchling and adult turtles find their
way along their migratory pathway? What
methods did scientists use to identify the
mechanism responsible for long distance
navigation in sea turtles?
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Navigation Strategies
Compass navigation
– Using the sun (starlings)
Sunlight
Sunlight
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Navigation Strategies
Compass navigation
– Using the stars (Indigo buntings)
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Navigation Strategies
Olfactory cues: Detection of dimethyl
sulphide (DMS)
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Case Study
Questions
5. Birds might use DMS to navigate. What
produces DMS and what methods did
researchers use to determine this? In what
oceans has DMS been measured?
6. What about seals? Why do the researchers think
that seals use visual cues to navigate?
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Case Study
Questions
7. Why did the researchers discount the possibility
of geomagnetic, celestial, acoustic and olfactory
cues as navigational tools in seals?
8. Migrating in the open ocean can be more
challenging than a land migration. Describe
these differences.
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Image Credits
Slide 1
Photo ©Nexus7 | Dreamstime.com, ID#28139654, licensed for use.
Slide 2
Photo by Hila Shaked, “Hatchling Loggerhead sea turtles near Atlit, Israel, on their way to the ocean,”
http://commons.wikimedia.org/wiki/File:Hatchling_Loggerhead_Sea_Turtles_near_Atlit_Israel.jpg), CC BY-SA 3.0.
Slide 3 (left)
Photo of spawning sockeye salmon by Theinterior, http://commons.wikimedia.org/wiki/File:SockeyeSpawn_inAdams.JPG, CC BY 3.0.
Slide 3 (right)
Figure 5 from: Lohmann, K. J., Lohmann, C.M.F. , and Endres, C.S. 2008. The sensory ecology of ocean navigation. J Exp Biol June 2008 vol. 211 no. 11 17191728. http://jeb.biologists.org/content/211/11/1719/F5.expansion.html#ref-19.
Slide 4 (left)
Crop of Fig 3 in:
Lohmann, K. J., Lohmann, C. M. F. and Endres, C. S. 2008. The sensory ecology of ocean navigation. J. Exp. Biol. 211: 1719–1728. Available online at
http://jeb.biologists.org/content/211/11/1719.long. Last accessed March 27, 2014. CC-BY 3.0.
Slide 4 (right)
Distribution of the northern elephant seal (dark blue: breeding colonies; light blue: non-breeding individuals) , by Mirko Thiessen,
http://en.wikipedia.org/wiki/File:Mirounga_angustirostris_distribution.png, CC BY-SA 3.0.
Slide 6
National Park Service, US Department of the Interior. Humpback Whale (Megaptera novaeangliae).
http://www.nature.nps.gov/biology/migratoryspecies/humpbackwhale.cfm.
Slide 7 (left)
Photo of ant trail by Wikipedia User:Fir0002, http://commons.wikimedia.org/wiki/File:Ant_trail.jpg, CC BY-SA 3.0.
Slide 7 (right)
Julius Neubronner's tiny cameras strapped to homing pigeons, http://commons.wikimedia.org/wiki/File:Pigeoncameras.jpg, public domain.
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Slide 8
Created by author.
Slide 9
NASA, http://www.nasa.gov/images/content/607968main_geomagnetic-field-orig_full.jpg.
Slide 10
Schematic of experimental setup and photo of turtle in harness provided by The Lohman Lab, Department of Biology, University of North Carolina, Chapel
Hill, NC (http://www.unc.edu/depts/geomag/), used with permission.
Slide 12
Figure 7 in:
Pósafi, M., and R. E. Dunin-Borkowski. 2009. Magnetic nanocrystals in organisms. Elements 5: 235-240. Used with the permission of the Mineralogical Society
of America.
Slide 13
Panels B and C of Figure 4 in:
Pósafi, M., and R. E. Dunin-Borkowski. 2009. Magnetic nanocrystals in organisms. Elements 5: 235-240. Used with the permission of the Mineralogical Society
of America.
Slide 15
Adapted from Fig. 27.21, page 603 In: Hickman CP, Roberts, L.S. Keen, SL, Larson, A., I’Anson, H and Eisenhour, D.J. (2008). Integrated Principles of Zoology.
14th ed. McGraw-Hill, Boston. ISBN 978-0-07-722126-3.
Slide 16
Modified from: Emlen, ST (1967). Migration orientation in the Indigo Bunting, Passerina cyanea: Part 1 Evidence for the use of celestial cues. The Auk, 84: (3)
309-342. https://sora.unm.edu/sites/default/files/journals/auk/v084n03/p0309-p0342.pdf
Slide 17
Figure 1 in: Nevitt, G. A. and Bonadonna, F. 2005. Sensitivity to dimethyl sulphide suggests a mechanism for olfactory navigation by seabirds. 1: 303305.
Available online at http://rsbl.royalsocietypublishing.org/content/1/3/303.full. Used with permission.
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