Presentation is loading. Please wait.

Presentation is loading. Please wait.


Similar presentations

Presentation on theme: "Biosonar/Echolocation"— Presentation transcript:


2 Biosonar/Echolocation
Odontocetes Toothed whales Dolphins, porpoises, sperm whales Bats Cave swiftlets Used for navigation, hunting, predator detection, …. primary sense in these animals

3 Signals from Different Species
Odontocetes that whistle (Type II – near & offshore, social, low object density) Bottlenose dolphin Beluga False killer whale Odontocetes that DO NOT whistle (Type I – near shore and riverine, dense complex environment) Family Phocoenidae (Harbor porpoise, Finless porpoise, Dall’s porpoise) Genus Cephalorhynchus (Commerson’s dolphin, Hector’s dolphin)

4 Typical echolocation signals
non-whistling odontocete Phocoena phocoena SLpp ~ dB 200 s 50 100 150 200 FREQUENCY (KHZ) 0.2 0.4 0.6 0.8 1 Tursiops Phocoena RELATIVE AMPLITUDE whistling dolphin Tursiops truncatus SLpp ~ dB 200 s Smaller animals have amplitude limitations, so emit longer sounds?

5 Echolocation clicks Capable of whistling Non-whistling

6 Sending sound - melon

7 Click variability

8 Sending and receiving sound

9 Dolphin phonic lips 2 pairs One right, one left Can work independently
Endoscope view Ted Cranford

10 Bottlenose dolphin phonic lips
Cranford et al. 1996

11 Sound reception No pinna!
External opening = 3mm, plugged, no connection with tympanic bone No pinna! Norris (1968)’s Theory = Sound conveyed to middle and inner ear through acoustic fats in lower jaw.

12 “Acoustic fat” found ONLY here & melon
Receiving sound “Acoustic fat” found ONLY here & melon CT scan from Darlene Ketten

13 Evidence: Brill et al. (1988)
Behavioral Approach Blindfolded dolphin discriminates between aluminum cylinder & sand-filled ring Two hoods worn on lower jaw Gasless neoprene: doesn’t block sounds Closed cell neoprene: blocks sounds Performance No hood vs. Gasless hood = no significant difference No hood vs. Closed cell hood = significant!

14 Sperm whale morphology
Clicks have 235 dB source level! CT scan from Ted Cranford

15 Funding science (an aside)


17 Sperm whale phonic lips
Ted Cranford

18 Sperm whale click Mohl et al 2003

19 Sperm whale directionality

20 Sperm whale beam pattern

21 Dolphin Receive and Transmit Beams
-30 dB -20 dB -10 dB 0 dB 0 ° 20 ° -40 ° 40 ° -20 ° -30 ° 10 ° 30 ° -10 ° Transmit Au, W.W.L. and P.W.B. Moore, 1984

22 Click trains

23 Source level and range – regular clicks

24 Click timing – regular clicks

25 Final approach to target
“Terminal buzz” – dolphins “Creak” – sperm whales Function? Freq (kHz) Time (s)

26 Terminal buzz – beaked whales
Search Approach Attack? Recorded on a D-tag Madsen et al. 2005

27 Click timing

28 Click intensity

29 Track of beaked whale Coloration is roll of animal

30 Buzz before impact

31 Discrimination capabilities
Cylindrical targets with 0.2 mm wall thickness difference Au, 1993

32 Summary of echolocation clicks
Short, loud, broadband signals High resolution Outstanding Discrimination capabilities Highly directional Emitted in trains Spacing 2 way transit time + processing Variable by species Porpoises longer and narrower bandwidth Delphinids shorter and wide bandwidth Sperm whales much lower frequency Variable in individual By task/target With range Deformations of melon

33 The other side – fish hearing
Clupeoid fish Herring, shad, menhaden, sardine, anchovy Swimbladder morphology facilitates broad frequency hearing range 2 ‘fingers’ of swimbladder surround auditory bullae Can they hear (and respond to) the acoustic signals of a primary predator?

34 Herring feeding rate Control Click train Regular clicks

35 Fish polarization Control Click train Regular clicks

36 Herring swimming depth

37 Conclusions Respond to echolocation clicks
Stop feeding School Swim down Swim faster Do not respond to other signals in same frequency range Can hear and appropriately respond to predator cue

38 Prey stunning by sonar signals
Benoit-Bird et al 2006 Prey stunning by sonar signals Hypothesis Odontocetes use acoustic signals to capture prey Stun, disorient, debilitate prey Existing support Sperm whales – rapid swimming prey in stomachs intact Fish school depolarization while under attack in captivity Fish lethargy while under attack in wild Some acoustic signals can injure/kill fish

39 Some acoustic signals can affect fish
Observed effects Loss of buoyancy control Abdominal hemorrhage Death Sound characteristics Fast rise times High pressures Examples Explosives Dynamite, TNT dB Black powder dB Spark discharges dB Dolphin click levels dB

40 Problem Odontocete signals of intensities observed to affect fish not observed in nature Question Can odontocete click trains or bursts debilitate fish?

41 Video camera Calibration hydrophone Monofilament enclosure Video camera Transducers

42 Fish responses 15 minutes pre-exposure observation
15 minutes post-exposure observation Fish behavior observed Changes in activity level Changes in pitch/roll Post-experiment survival

43 Signals Bottlenose dolphin Killer whale Sperm whale SL = 203 dB
EL = 212 dB 50 100 150 200 -60 -50 -40 -30 -20 -10 250  s Bottlenose dolphin 50 100 150 200 -60 -50 -40 -30 -20 -10 250  s SL = 200 dB EL = 208 dB Killer whale SL = 187 dB EL = 193 dB 50 100 150 200 FREQUENCY (KHZ) -60 -50 -40 -30 -20 -10 500  s Sperm whale

44 Pulse rates Static pulse rate Modulated pulse “sweeps”
100, 200, 300, 400, 500, 600, & 700 pulses/second Exposure times of 7 seconds – 1 minute 6 individuals of 2 species (sea bass, cod) Groups of 4 individuals of each species Modulated pulse “sweeps” From 100 to 700 pulses/second in 1.1, 2.2, 3.2 seconds Similar to a “terminal buzz” 6 individuals of 2 species (cod, herring)

45 Subject selection Proposed “stunning” mechanism: Acoustic interaction with air-filled cavities Swim bladder Physostomous “Open” - Air comes from gulping at surface Physoclistous “Closed” - Air is produced biochemically “Stunning” proposed from field observations Salmon Physostomous Anchovy Physostomous with extensions to lateral line & labyrinth Mahi mahi No swim bladder 3 species commonly preyed upon by Odontocetes Variety of swimbladder types

46 Herring (Clupea harengus)
Physostome with air bladder extensions to labyrinth & lateral line - Increased sensitivity to sound - Respond to echolocation signals Modified primitive form

47 Sea Bass (Dicentrarchus labrax)
Euphysoclist - Physostome juvenile - Physoclist adult Intermediate form

48 Cod (Gadus morhua) Physoclist Most derived form

49 Results

50 Results No measurable change in behavior No mortality
Swimming activity Balance/buoyancy control Orientation No mortality Variables explored Frequency of signal Pulse rate “Terminal buzz” simulation Long exposure times Multiple individuals, different sizes, different species

51 Conclusions No response to stimuli
Signals near maximums recorded for odontocete clicks Stimulation with odontocete-like clicks alone is not enough to induce fish stunning Additional stress? Other sensory inputs? Odontocete behavior?

Download ppt "Biosonar/Echolocation"

Similar presentations

Ads by Google