Biosonar/Echolocation Odontocetes Toothed whales Dolphins, porpoises, sperm whales Bats Cave swiftlets Used for navigation, hunting, predator detection, …. primary sense in these animals Signals from Different Species
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SLpp ~ 190 - 225 dB
Typical echolocation signals
Smaller animals have amplitude limitations, so emit longer sounds?
Capable of whistling
One right, one left
Can work independently
Cranford et al. 1996
External opening = 3mm, plugged, no connection with tympanic bone
Norris (1968)’s Theory = Sound conveyed to middle and inner ear through acoustic fats in lower jaw.
“Acoustic fat” found ONLY here & melon
CT scan from Darlene Ketten
Clicks have 235 dB source level!
CT scan from Ted Cranford
Mohl et al 2003
Recorded on a D-tag
Madsen et al. 2005
Coloration is roll of animal
Cylindrical targets with 0.2 mm wall thickness difference
Dolphin click levels 225 dB
Physostome with air bladder extensions to labyrinth & lateral line
- Increased sensitivity to sound
- Respond to echolocation signals
Modified primitive form
- Physostome juvenile
- Physoclist adult
Most derived form