Alt muligt jeg manglede (magneto, vision and sensory ecology) Flashcards
What are some of the high quality info that can be obtained from vision?
Many details, highly directional, fast (speed of light)
How many times have eyes evolved?
MANY times –> huge diversity
In what visual field are rod cells functional?
Peripheral vision
What are the fovea responsible for?
Color vision and acuity
Which opsin does the rod cells contain?
RHO (blue light)
Describe how light influences the circadian rythm.
Melatonin levels rises during night time
Describe the photoreceptors of the fruit fly eye.
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
What is the retina, and what cells are found in the retina (human)?
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)
How does the retina of insects differ from that of humans?
Everted, 4-8 PR-cells in each ommatidia
Describe the fovea in insects.
An area with smaller interommatidial angle = acute zone
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?
6-7 log units
What is responsible for which colour spectrum the opsin is responsible for?
A few amino acids
Describe what the dynamic range means in dark habitats vs light habitats.
Dark: many active opsins
Light: less active opsins
Describe how colour vision is dependent on the three different opsins.
All three must be active: releative response from all three => combined probability
How many different opsins does the mantis shrimp have?
13
What are the fastest and the slowest eyes known in relation to fff?
300 Hz (dragon fly) vs 0.5 Hz (starfish)
How is the fff dependent on depth?
Because of temperature (slows down all physiological functions). Tuna heat up retina by swimming –> rising fff
Mention some taxa that use magnetoreception.
Mollucks (snails), athropods (crustacean, insects), vertebrates (birds, mammals, amphibias)
How do finite senses cope with infinte input?
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
What is the discriminable range limited by (sensory ecology)?
Noise
Describe what is meant by receptor noise.
Noise present in receptors as result of (e.g.) thermal motion of molecules –> the receptor potential is thus not constant but jitters
Describe what is meant by channel noise.
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
Describe what is meant by environmental noise.
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.
Why are matched filters a good idea?
To filter out unnecessary info, and in many cases to enhance important info
Simplifies processing, freeing the brain
Matched filter has evolved in all aspects of animals lifes, but especially in what?
It’s interaction with the environment, e.g., the eye: matched to the spatial layout of the habitat
How many eyes does the tripedalia gople has?
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
Why is the eye tremor necessary?
Several functional reasons, but one is to prevent adaptation to constant stimulation and optimize contrast
