document

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
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
Dermoptera vs. Chiroptera – gliding membrane
Wing shape and flight dynamics
Wing aspect ratio
(length/width)
Artibeus
(low aspect ratio)
Eumops
(high aspect ratio)
Echolocation
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
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.
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
Bat ear shapes
Bat facial structures
Yinpterochiroroptera
Cardioderma (Megadermatidae)
Hipposideros (Hipposideridae)
Yangochiroroptera
Murina (Vespertilionidae)
Lonchorhina (Phyllostomidae)
“ 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
Basic types of “microchiropteran” calls
Broad FM
(frequency
modulated
harmonics)
FM
(frequency
modulated)
Initial CF
(“constant”
frequency)
Teriminal FM
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)
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/uploa
ds/joesze.Euderma_maculatu
m_1.wav
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/upload
s/joesze.Myotis_ciliolabrum_5
.wav
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)
High duty cycle bats (Rhinolophidae)
Constant Frequency (CF)
Rhinolophus megaphyllus
http://batcalls.org/prod/uploads/ml
wen.Rhme-08Nov03-0457.wav
Rhinolophus hipposideros
http://batcalls.org/prod/uploads/wille
mhol.Rhin_hipp_Dordogne_0806200
5_A2_12000_290000.wav
High duty cycle bats (Hipposideridae)
Constant Frequency + Frequency Modulated (CF/FM)
Hipposideros abae
Hipposideros commersoni
CF component
FM component
Second harmonic
First harmonic
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)
Bat evolution:
flight first or echolocation first?
Comparative morphology
(size of cochlea)
CF
CF/FM
fossils
FM
no laryngeal
echolocation
“Microchiroptera”
paraphyletic
THE ABSENCE OF
LARYNGEAL
ECHOLOCATION
IN PTEROPODIDS
IS APPARENTLY
DERIVED
YINPTEROCHIROPTERA
YANGOCHIREROPTERA

Download Report