Sensing the Environment I:
Worksheet 2.7
Supplemental Instruction
Iowa State University
Leader:
Course:
Instructor:
Date:
Hannah
AECL 365
Dr. Waldman
10-13-15
1.) Name some reasons that indicate why the senses are important.
 Help detect heat, light, pressure, other organisms (predators, prey)
 Define and limit known world (if can’t smell it/detect it, don’t know its there)
 Sense organs enable vertebrates to monitor the environment and permits
evolution of complex behaviors
2.) The more __variable___ environment, the greater __advantages___ of sense organs to
survive.
a. __Behavior___ is constrained by limits of the sensory systems.
3.) Name the 3 types of sense organs and examples of each.
 1) Chemoreceptors smell and taste
 2) Mechanoreceptors touch & pain; hearing/lateral line; equilibrium
 3) Electromagentic light (vision); heat; electrical/magnetic (animal
navigation)
4.) Chemoreception is the most _ancestral____ and __universal____ of the sense organs.
_Smell__ is more sensitive & more complex than taste.
5.) Taste __receptor___ cells are located in the taste buds.
a. What are the 5 basic tastes?
 Umami (savory)
Sweet
 Sour
Bitter
 Salty
b. Which of the 5 is an important warning sign of toxicity?
 Bitter
6.) Chemical scents have a variety of important functions. List a few.
 Recognition species, ex, individuals, predators, prey, etc.
 Emotional states e.g. fear, readiness to mate
 Advertisement e.g. territorial, mating
 Orientation e.g. scent tracks
7.) The mechanoreceptors are located in the _skin (dermis)____.
8.) Touch/Pain is sensed by __distorted____ nerve tissue and sends information off to the
CNS. If the touch/pressure is sustained, the nerve tissue __adjusts_____.
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9.) Explain what a lateral line is and who uses it. What behavior is it important in?
 Lateral line distant pressure receptor for detecting wave vibrations and
currents in water (helps detect nearby movements of prey, predators, mates, or
just position of static objects)
o Found in fish, frogs, and adult salamanders
o Important in fish schooling behavior
 When water displaced, moves hair cells in the cupula, which are connected to
neuromast cells: sends nerve signal to brain
10.) How does the transmission of sound differ in water than in air?
 In water:
o More difficult to initiate (water is more dense than air)
o Once initiated, transmission (speed) more rapid (5x)
o Speed slows down in colder and deeper waters
11.) Frequency determines the _pitch___ (high or low) while amplitude determines
__loudness___ (volume).
12.) The original function of the vertebrate ear was for _balance____.
a. The actual organ responsible for this function is called the ___labyrinth____.
13.) Hearing in mammals begins in the middle ear with 3 subdivisions. Name each of these,
their function, and their components.
 Outer ear collects sound waves and take to tympanic membrane
(eardrum)—vibrates
 Middle ear air-filled chamber with 3 bones (malleus, incus, stapes = middle
ear ossicles)
o Ossicles amplify vibrations (sound) coming from eardrum
 Inner ear contains the cochlea ( = organ of hearing; filled with liquid and
uses hair cells to detect movement)
o Receive vibrations from middle ear
o Send info to the CNS
14.) In the mammalian inner ear, pitch discrimination depends on the __location__ of hairs
stimulated but loudness depends on the __number___ of hairs stimulated.
15.) _Fish__ hear low sounds best. __Mammals____ have the broadest range of hearing
while ___birds____ have a very narrow hearing range.
16.) Describe the hearing (ear) specialization in owls.
 Broad skull helps because further ears are apart, better hearing for distances
 Asymmetrical ears (in size and position)
 Sound catching facial disc (brings in sound to ears)
o Sound arrives separately to each ear
o Serves for directional hearing (can tell which direction sound came from)
 **Helps for prey location in the dark!
17.) __Sonar/Echolocation____ involves emitting a high frequency sound, which is then
bounced back off of prey and objects. This is used for prey location in the dark and or
murky waters.