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passage 3
P1
Scientists have long known that the soft surface of the bill of the platypus is perforated with openings that contain sensitive nerve endings. ████ █████████ ████████ ████ ██████████ █████████ ██ ███ █████ ██ ███ ████████ ████ ███ ██████ ████ ███ ████ ██ ██████ ███ ████ █████ ███████████ █ ██████████ █████████ ██ ███ ████ ████ ███ ████████ █████ █████ ███ ████████ ███ ██████ ████ ██ ██ ██████████ ███
Biologists' conclusion ·
Platypus uses its bill to locate prey underwater
We've known for a long time that the bill has nerve endings. Now biologists think those nerves on the bill are used for finding prey underwater.
New evidence supporting conclusion ·
Neurophysiological studies
Studies reveal two sensory receptors in pores on platypus bills: mechanoreceptors (respond to physical pressure), and electroreceptors (respond to electrical fields).
Bohringer's conclusion ·
Bill is the primary sensory organ for the platypus
This was supported by studies showing the bill is sensitive to touch.
Puzzle ·
How does platypus locate prey at a distance?
If a platypus isn't touching its prey with its bill, how can it find the prey? (Probably has to do with the electroreceptos, since we discussed the mechanoreceptors earlier.)
P2
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Set-up for Scheich's hypothesis ·
Platypus hunts by steadily wagging bill, then moving bill erratically after prey it finds prey
The erratic movements are called "searching behavior."
Scheich's hypothesis ·
Platypus distinguishes prey from non-prey by detecting electric fields
Scheich's experiment ·
Confirms platypus can detect electric fields
Platypus switches to searching behavior when it encounters electric field from battery. Then platypus attacked the battery like it was food.
Scheich's speculation ·
All invertebrates that platypus eats produce electric fields
We already know that shrimp prey of platypus produces an electric field.
Passage Style
Phenomenon-hypothesis
Single position
20.
It can be inferred from ███ ███████ ████ ██████ ██████████ █████████ ███ ████████ ██ ██████████ ██
a
capture prey that ██ ███ ████████
b
distinguish one kind ██ ████ ████ ███████
c
detect electric fields ████████ ██ █████████ ████
d
stimulate its mechanoreceptors
e
pick up the █████ ██ ███ ████