Chapter 7: Part 2

Question 1

Opsins

Answer 1

• photoreceptor protein
• protein required for color vision

Question 2

Retinal

Answer 2

• photoreceptor protein
• When the retinal molecule absorbs a photon of the appropriate wavelength, the molecule changes shape, contributing to a nervous impulse by the photoreceptor cell

Question 3

Opsin and Retinal

Answer 3

• Variations in the specific amino acids that hold on to the retinal molecule within the opsin produce differences in the wavelengths absorbed by the pigment in different photoreceptor cells

Question 4

rods

Answer 4

• respond to light intensity
• no color
  -black and white

Question 5

How many types of cones do birds have?

Answer 5

4
- UV/violet cones (UV/ short WL sensitive)
- blue cone (short wavelength sens.)
- green cone (middle wavelength sens.)
- red cone (long wavelength sens.)
- ^^double cone of this (long-wavelength sens.)

Question 6

How do avian cones compare to mammal cones?

Answer 6

• the UV/violet cone is unique to birds!
• humans only have 3

Question 7

What is the function of oil droplets in the cone cells?

Answer 7

-carotenoid filled organelle, filters light
- filters before reaching visual pigments, enhances color
- refine the spectral sensitivities of the (A) violet-type and (B) ultraviolet-type avian visual systems

Question 8

External acoustic meatus/ External ear

Answer 8

• short external passage, covered by feathers
• often surrounded by muscle to partially or fully close the ear

Question 9

auricular feathers

Answer 9

• around ear opening
• protect when diving sound of wind

Question 10

Middle ear

Answer 10

• includes tympanic membrane and collumella

Question 11

Tympanic membrane

Answer 11

• carries sound waves into the ear, into the middle ear cavity
  travel:
• stapes&raquo_space; oval window&raquo_space; tectorial membrane&raquo_space;basilar membrane&raquo_space; cochlea&raquo_space; round window

Question 12

Columella

Answer 12

• aka stapes
  -the middle ear
• connects tympanic membrane to the pressure sensitive fluid system of the inner ear

Question 13

Inner ear

Answer 13

• includes the cochlea
• organ of corti

Question 14

Cochlea

Answer 14

• fluid filled coiled section of the inner ear that is the base of the hearing organ
• includes lagena and organ of corti

Question 15

organ of corti

Answer 15

• a structure in the cochlea of the inner ear which produces nerve impulses in response to sound vibrations
• fluid vibrations has membrane move in turn to hair cells

Question 16

How do birds compare to mammals in regards to hearing ability?

Answer 16

• most birds can detect sounds within a range similar to humans

Question 17

How are owls special in hearing abilities?

Answer 17

• owls can hear in a really low register
• have adaptations for hearing in the dark (facial disk with facial ruff of feathers that reflect sounds into the ears)
• Assymetrical ears
• two coordinate system

Question 18

asymmetrical ears of owls

Answer 18

• with one being higher on the head than the other, and one ear canal aimed upward and the other downward
• This arrangement enables these owls to localize sounds in the vertical dimension as well as from side to side, resulting in a very sophisticated auditory map

Question 19

Two coordinate system

Answer 19

• detects both the elevation of the sound (the vertical dimension, how high or low it is) and its azimuth (the horizontal dimension, how far to the left or right)

Question 20

Echolocation

Answer 20

• Occurs in 2 families of birds: Steatornidae (oilbirds) and Apodidae (cave swiftlets)
• Used for orientation in dark caves
• Echolocate by producing clicking sounds and then receiving and interpreting the resulting echo

Question 21

How do the semicircular canals function and what kind of motion do they detect?

Answer 21

• work together to sense rotational and angular movements of the head
• they sense motion via the ampulla, a bulb-shaped structure, has hair cells
• have canal for anterior, posterior, and horizontal
• has pressure exerted by stationary fluid on the cupula in the middle of the semicircular duct, causing rotation of head

Question 22

Herbst corpuscle

Answer 22

• layer of “squishy” tissue
• The most elaborate of avian tactile sensors, it consists of as many as 12 onion-like layers of external lamellae that transfer slight pressure changes to the elaborate nerve ending of the receptor axon in the center
• Also found in feather follicles, joints

Question 23

How are herbst corpuscles used to detect hidden/buried prey items?

Answer 23

• The pressure gradient created in the mud by the insertion of bird’s beak (red) is distorted locally by a solid object, like a mollusk shell
• The variation in pressure induced by the shell (blue) is detectable as a difference between the two side of the tip of the beak by the Herbst corpuscles under the ramphotheca
• example: kiwis, red knot

Question 24

How do birds compare to mammals in terms of the number of taste receptors?

Answer 24

• Most birds have about 300 taste buds, the majority of which occur on the roof of the mouth or deep within the oral cavity
• Compared with mammals, birds have few or no taste buds on the tongue
• humans have 10,000 taste buds on tongue

Question 25

Understand how hummingbirds have evolved a modified umami receptor (T1R3) to be able to
detect sweet tastes

Answer 25

• Umami (savory): sensed by taste buds with a combination of T1R1 and T1R3 proteins
• All living birds lack the T1R2 gene – have no sweet receptors
• hummingbirds evolved specific amino acid changes to the binding domain of T1R3 to enable it bind sugars

Question 26

Where is the olfactory epithelium located

Answer 26

• in turbinates(conchae) of birds, aka “nose”
  -various levels of smell

Question 27

What is the relationship between oflactory bulb size and foraging

Answer 27

• the larger the bulb, the higher detection threshold for foraging

Question 28

How do seabirds (like albatrosses) search for food? What chemical cues do they use?

Answer 28

• tend to fly crosswind, optimizing the likelihood of encountering an odor plume of prey.
• Once detected, these birds use a zigzag flight pattern to approach their prey, beginning their decent about 2.5 kilometers downwind of the capture site.

Question 29

How do kiwis search for food?

Answer 29

• using herbst corpuscles!