pressure sensory mechanism for prey detection in birds- T.Piersma, R.Aelst Flashcards
what are red knots and where do they occur?
sandpipers in coastal intertidal areas
with dry sand could they discriminate between food and non food items?
no
what can Herbst corpuscles measure and why?
acceleration due to pressure change
accelerating pressure build up
what can the bills detect in soft sediment?
perception of a pressure gradient
object blocks pore water flow
what can repeated probing in soft wet sediment allow?
allows the birds to induce residual pressure disturbance from a nearby object
where do red knots tend to eat invertebrates?
arctic tundra breeding ground
what were the 3 types of buckets?
- no prey
- 15 buried bivalves
- 15 buried stones
which feeder would they go to if the bucket had objects?
right
what % showed correct choice indicating they could discriminate between buckets?
60%
what may be a possible reason for them making mistakes?
strategically to see if there are alternative cues
in light microscopy what did the silver staining show?
corpuscular nerve endings
what were the scanning electron microscopes used to show?
presence of sensory pits
in the training phase how many trials did it take for preference to be significant?
120
when buried in dry sand after how many trials were they still on the 50% line?
328
what do they have in lacunae sensory pits?
high numbers of Herbst corpuscles
where is the largest density of sensory pits?
tip of the bill
what is found under keratin spines on the palate and what do these detect?
grandly corpuscles- velocity detectors
where is the detection of buried objects weaker?
in dry sand
in the dry sand what is the air near the probing bill?
what is the resistance from sand pores?
easily compressed
low resistance
in wet sand:
a) what is the interstadial water like?
b) what does the pressure from the probing bill drop over?
c) what is the water resistance like between sand grains?
d) what takes time?
a) nearly incompressible
b) a large distance
c) high
d) relaxation of increased pressure
with a hard object why is the pressure pattern not disturbed?
flow must go around the object
if sand is loose and mobile what does the probing bill do to the water?
increases pressure
when the bill is retreated what happens to the sand grains?
rearranged, denser packing and so an increased pressure build up
what is the birds preferred feeding terrain?
sandy with a film of moisture
what is pressure pattern dominated by?
radial decay
what is darcys law?
pressure gradient balanced by frictional drag of pore water flow
flow is proportional to pressure gradient
