Alt muligt jeg manglede (magneto, vision and sensory ecology)

Question 1

What are some of the high quality info that can be obtained from vision?

Answer 1

Many details, highly directional, fast (speed of light)

Question 2

How many times have eyes evolved?

Answer 2

MANY times –> huge diversity

Question 3

In what visual field are rod cells functional?

Answer 3

Peripheral vision

Question 4

What are the fovea responsible for?

Answer 4

Color vision and acuity

Question 5

Which opsin does the rod cells contain?

Answer 5

RHO (blue light)

Question 6

Describe how light influences the circadian rythm.

Answer 6

Melatonin levels rises during night time

Question 7

Describe the photoreceptors of the fruit fly eye.

Answer 7

Rh1: broadspectrum/sensitivity
Rh3/4: UV light
Rh5: blue light
Rh6: green light

3+5 and 4+6 are coexpressed by R7 and R8, whereas R1-6 express Rh1

Question 8

What is the retina, and what cells are found in the retina (human)?

Answer 8

The light sensing part of the eye
Inverted retina in human eye: light passes several layers of neurons before reaching the receptors

Ganglion cells (transmitting to the optic nerve) –> amacrine cells and bipolar cells –> horizontal cells –> photoreceptor cells (rods and cones)

Question 9

How does the retina of insects differ from that of humans?

Answer 9

Everted, 4-8 PR-cells in each ommatidia

Question 10

Describe the fovea in insects.

Answer 10

An area with smaller interommatidial angle = acute zone

Question 11

The dynamic range of human vision is due to the dynamic shift in 11-cis:all-trans retinal ratio. How many log units can this dynamic range shift?

Answer 11

6-7 log units

Question 12

What is responsible for which colour spectrum the opsin is responsible for?

Answer 12

A few amino acids

Question 13

Describe what the dynamic range means in dark habitats vs light habitats.

Answer 13

Dark: many active opsins
Light: less active opsins

Question 14

Describe how colour vision is dependent on the three different opsins.

Answer 14

All three must be active: releative response from all three => combined probability

Question 15

How many different opsins does the mantis shrimp have?

Answer 15

13

Question 16

What are the fastest and the slowest eyes known in relation to fff?

Answer 16

300 Hz (dragon fly) vs 0.5 Hz (starfish)

Question 17

How is the fff dependent on depth?

Answer 17

Because of temperature (slows down all physiological functions). Tuna heat up retina by swimming –> rising fff

Question 18

Mention some taxa that use magnetoreception.

Answer 18

Mollucks (snails), athropods (crustacean, insects), vertebrates (birds, mammals, amphibias)

Question 19

How do finite senses cope with infinte input?

Answer 19

They don’t -
Senses are evolved to match the response range that is most beneficial to their chances of survival
Sensory systems are evolved to maximize the number of discriminable levles of the stimulus within this range

Question 20

What is the discriminable range limited by (sensory ecology)?

Answer 20

Noise

Question 21

Describe what is meant by receptor noise.

Answer 21

Noise present in receptors as result of (e.g.) thermal motion of molecules –> the receptor potential is thus not constant but jitters

Question 22

Describe what is meant by channel noise.

Answer 22

Noise caused by fluctations in the incoming stimulus signal, e.g., the intensity of a sound reaching our ear will fluctate randomly due to random fluctations in the density and volume of the intermediate air

Question 23

Describe what is meant by environmental noise.

Answer 23

Noise created by competing sources, whose output is usually not random, e.g., the sound reaching our ear may be contaminated by other sounds that worsen our ability to detect the wanted sound reliably.

Question 24

Why are matched filters a good idea?

Answer 24

To filter out unnecessary info, and in many cases to enhance important info
Simplifies processing, freeing the brain

Question 25

Matched filter has evolved in all aspects of animals lifes, but especially in what?

Answer 25

It’s interaction with the environment, e.g., the eye: matched to the spatial layout of the habitat

Question 26

How many eyes does the tripedalia gople has?

Answer 26

4 rhopalia with 6 eyes each - the upper and lower lens eyes resembles vertebrate eyes, and are image forming
Other types of eyes: pit and slit

Question 27

Why is the eye tremor necessary?

Answer 27

Several functional reasons, but one is to prevent adaptation to constant stimulation and optimize contrast