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BAT FLIGHT AND ECHOLOCATION

BAT FLIGHT AND ECHOLOCATION. http:// www.arkive.org/species/ARK/mammals/Myotis_daubentonii/Myotis_daubentoni_08.html?movietype=wmMed. Structure of bat wings. Comparative structure of vertebrate wings. Bat & Bird comparison. Mechanical efficiency. Origin of bat flight.

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BAT FLIGHT AND ECHOLOCATION

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  1. BAT FLIGHT AND ECHOLOCATION http://www.arkive.org/species/ARK/mammals/Myotis_daubentonii/Myotis_daubentoni_08.html?movietype=wmMed

  2. Structure of bat wings

  3. Comparative structure of vertebrate wings

  4. Bat & Bird comparison

  5. Mechanical efficiency

  6. Origin of bat flight Gliding as an intermediate stage Multiple independent origins among living mammals Marsupials – 1 Order, 3 Families Placentals – 2 Orders, 3 Families http://www.arkive.org/species/GES/mammals/Petaurus_gracilis/Petaurus_gracilis_00.html?movietype=wmMed

  7. Dermoptera vs. Chiroptera – gliding membrane

  8. Wing shape and flight dynamics Wing aspect ratio (length/width) Artibeus (low aspect ratio) Eumops (high aspect ratio)

  9. Echolocation

  10. Characteristics of sound AMPLITUDE (loudness) 20 dB – whisper 60 dB -- conversation 130 dB – pain threshold Bat echolocation 60 – 120 dB 1400 Hz (1.4 kHz) FREQUENCY Human hearing 0.02 – 20 kHz Bat echolocation 9 – 200+ kHz http://www.asel.udel.edu/speech/tutorials/acoustics/sn_h7.wav

  11. Characteristics of sound ATTENUATION of sound (rate of energy loss) Increases with frequency ECHO attenuation Increases with frequency HOWEVER Higher frequencies produce echoes from smaller objects.

  12. Characteristics of sound in echolocation High frequencies more effective in locating small targets but have limited range Low frequencies increase detection range but limit resolution of target Constant frequency (CF)allows for precise location via doppler shift (i.e., returning sound has a shifted freqeuncy) Multiple frequencies (broad band) provide more information about target shape Harmonics Frequency modulation (FM) –frequecny sweep

  13. Bat ear shapes

  14. Bat facial structures Yinpterochiroroptera Cardioderma (Megadermatidae) Hipposideros (Hipposideridae) Yangochiroroptera Murina (Vespertilionidae) Lonchorhina (Phyllostomidae)

  15. “ Tongue-clicking” echolocation Rousettus (Pteropodidae) Does not involve larynx. Sound pulses produced by in mouth with tongue Short duration pulses with wide frequency range. Effective for obstacle avoidance inside cave roosts

  16. Basic types of “microchiropteran” calls Broad FM (frequency modulated harmonics) FM (frequency modulated) Initial CF (“constant” frequency) Teriminal FM

  17. Perch-hunters & “whispering” bats Large ears for receiving low-frequency ambient sound from prey. Large eyes (also use vision to locate prey) Produce low amplitude FM “stealth” calls Nycteris (Nycteridae) Macroderma (Megadermatidae) harmonics Plecotus (Vespertilionidae)

  18. Low frequency FM bats Hunt in open habitat Produce high amplitude calls at low frequencies (some audible to humans) Large ears “tuned” to low frequencies Euderma maculatum (Vespertilionidae) http://batcalls.org/prod/uploads/joesze.Euderma_maculatum_1.wav

  19. Broad frequency FM bats Produce high amplitude calls with multiple harmonics over a broad frequency range, with downward-sweeping FM. Provide detailed information on shape and size of prey Myotis ciliolabrum http://batcalls.org/prod/uploads/joesze.Myotis_ciliolabrum_5.wav

  20. High duty cycle bats Fly in closed, cluttered habitat (forest interior). Emit very high frequency constant frequency (CF) calls, or CF and FM in combination, using Doppler shift to determine location and movement of prey. Elaborate nose involved in beaming calls and ear shape “tuned” to receive narrow-band echoes Rhinolophus (Rhinolophidae) Hipposideros (Hipposideridae)

  21. High duty cycle bats (Rhinolophidae) Constant Frequency (CF) Rhinolophus megaphyllus Rhinolophus hipposideros http://batcalls.org/prod/uploads/mlwen.Rhme-08Nov03-0457.wav http://batcalls.org/prod/uploads/willemhol.Rhin_hipp_Dordogne_08062005_A2_12000_290000.wav

  22. High duty cycle bats (Hipposideridae) Constant Frequency + Frequency Modulated (CF/FM) Hipposideros abae Hipposideros commersoni CF component FM component Second harmonic First harmonic

  23. Insulation from “self-deafening” Isolation of the otic capsule from cranium Dampening sound transmission through middle ear ossicles Tensor tympani (increasing tension on tympanum) Stapedius (regulates contact of stapes with cochlea)

  24. Bat evolution: flight first or echolocation first?

  25. Comparative morphology (size of cochlea) CF CF/FM fossils FM no laryngeal echolocation

  26. “Microchiroptera” paraphyletic THE ABSENCE OF LARYNGEAL ECHOLOCATION IN PTEROPODIDS IS APPARENTLY DERIVED YINPTEROCHIROPTERAYANGOCHIREROPTERA

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