Wk 8.doc

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29 Mar 2012
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NATURAL HISTORY NOTES – WEEK 8
ADAPTATIONS FOR FINDING PREY continued:
HEARING VERY SPECIALIZED IN BATS, DEPEND ENTIRELY ON IT FOR HUNTING
SOME ANIMALS FIND THEIR PREY IN A VERY DIFFERENT WAY:
BATS SEARCH FOR PREY BY USING SONAR:
HIGH FREQUENCY SOUND BOUNCES OFF OBJECT BACK TO BAT EARS DETECT, ANALYSE
INSTANTLY
BECAUSE BATS LISTEN TO ECHOES CALLED ECHOLOCATION
THREE PHASES TO ECHOLOCATION:
SEARCH PHASE: SHORT PULSES HIGH PITCHED SOUND (20-30 CALLS PER SEC)
1) DETECTION AND APPROACH PHASE: PULSES BECOME SHORTER IN DURATION, GIVEN
AT FASTER RATE (MORE FREQUENTLY)
2) TERMINAL PHASE: FASTEST RATES ; 500 CALLS PER SECOND = FEEDING BUZZ
WHY FASTER AT END? FINE RESOLUTION: ALLOWS DETECTION OF SMALL INSECTS
WHY NOT USE ALL THE TIME? ATTENUATES QUICKLY, DOESN’T TRAVEL AS FAR
SONAR: USED BY OTHER ANIMALS: SHREWS
OLFACTORY SENSE: SENSE OF SMELL
- ELONGATED SNOUT with INCREASED NUMBER OF SENSORY CELLS
- DENSE CONCENTRATIONS IN VOMERONASAL OR JACOBSON'S ORGAN
ENHANCE DETECTION BY SMELL BY HUNTING AT SPECIFIC TIME
FOXES, WOLVES, ETC. HUNT AT DUSK, IN EARLY NIGHT GROUND IS WARMER THAN AIR,
SCENT STAYS JUST ABOVE GROUND
SNAKESHUNT BY SMELLWITH TONGUEPICK UP SCENT MOLECULES IN AIR
SNAKE’S TONGUE FORKED, PULLS SCENTS INTO VOMERONASAL ORGAN IN ROOF OF MOUTH
DIFFERENT CONCENTRATION ON EACH FORK ALLOWS SNAKE TO PINPOINT DIRECTION OF
PREY
TACTILE SENSE = SENSE OF TOUCH
TACTILE SENSORS IN DIFFERENT LOCATIONS:
A) HANDS: RACCOON PAWS – HIGH DENSITY
B) NEAR MOUTH:
MAMMALS: A) WHISKERS NEAR MOUTH = VIBRISSAE FOX, OTTER
B) FLESHY NOSE PROTUBERANCES: STAR-NOSED MOLE
BIRDS: A) FEATHERS - WHISKER-LIKE NEAR BEAK , ALSO GUIDE AND CAPTURE:
FLYCATCHERS, GOATSUCKERS
B) BEAK : SANDPIPERS SUCH AS AMERICAN WOODCOCK – TIP HAS HERBST
CORPUSCLES = TACTILE SENSE
RECEPTOR CELLS REQUIRE PRESSURE (DUCKS HAVE THESE IN BILL TOO)
HEAT SENSOR: RATTLESNAKES - PIT BETWEEN EYES AND NOSTRILS IS SENSITIVE TO
INFRARED = BODY HEAT,
CHANGE OF ONLY 0.05 °C CAN BE DETECTED
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