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BIOL 350 > Sensory Ecology > Flashcards

Sensory Ecology Flashcards

1
Q

What is sensory ecology?

A

How organisms obtain information about their environment and how this affects their distribution, behaviour, etc.

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2
Q

What function does the information about the environment serve?

A

o Homeostasis (including regulation of temperature)
o Phenology (timing)
o Spatial orientation
o Defence
o Persuasion (signal to influence another individual)
- True communication or deception

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3
Q

Channels of information transfers

A

o Probably used initially to obtain information about food, predators and abiotic factors; some later used for intraspecific communication

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4
Q

Channels of information transfers - Electromagnetic and Thermal energy

A
  • Light
  • Infrared and thermal (snakes have heat-sending organs)
  • Electric (platypus have electroreceptors on bill)
  • Magnetic (beluga wales use earths magnetic field as info for orientation)
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5
Q

Channels of information transfers - Mechanical Energy and Force

A
  • Sound and sonar (bats)
  • Pressure
  • Touch and vibration
  • Gravity
  • Inertia
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6
Q

Channels of information transfers - Chemical

A
  • Taste
  • Smell
  • Humidity
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7
Q

Variables in type of signals

A

o Variation in range, rate, obstructed by barriers, dark use, deflected currents
- Electric is short range, visual in medium and olfactory auditory and magnetic are long
- Visuals are obstructed by barriers….some aren’t
o Variation in fade out time, localization
- Smells stay for a long time – but sounds don’t
- Is it possible for it to be in one small place or can it be coming from anywhere

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8
Q

Benefits and drawbacks of using light as communication

A
  • Benefits; potentially very detailed info very quickly

- Drawbacks; quick fadeout, and much variation, affected the most by environment, easily detected by predators

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9
Q

Benefits and drawbacks of using chemical channels as communication

A
  • Provides least detailed picture
  • BUT less affected by environment
  • Can be private, limiting detection by prey or even interspecific competitors
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10
Q

Electromagnetic and thermal energy: Vision

A
  • Ability to detect light
  • Best for scanning the environment, most directional and rapid
  • Most precise info on direction, distance and nature of objects
  • Not useful in dark or cluttered environments (forests)
  • Involved light-detecting organs (eyes) that have photoreceptors
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11
Q

Photoreceptor cells

A
  • Pigmented neurons with photoreceptor proteins
  • Part of all light-detecting organs
  • Development similar in all animals (indicative of very early origin)
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12
Q

Photoreceptor: Intensity detector

A
  • May be heat detectors
    Ex: bacteria and archaea; too small to detect direction
  • Photoreceptor proteins; bacteriorhodpsin…
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13
Q

Photoreceptor: Direction detector

A
  • Having more than one eye helps
    Ex: planaria (use their ocelli to move away from light) – orient so that light received by two ocelli is equal and minimal
  • Daphnia have one fused compound eye with several ommatidia (light detector found in insects and crustaceans) – each ommatidia has light focusing lens and detects light from a small portion of the visual field - use eye to avoid shore by orienting with shadow cast by shore at the rear and swimming until the light on all ommatidia is equal – also use as a cute of vertical migration (swim up in dim light and down in bright light) – several different pigments
  • Plants and fungi have phytochrome – detects red and far-red light; detect direction of light (used in phototropism, Photoperiodism…)
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14
Q

Photoreceptor: Image former (lenses)

A
  • In vertebrates and some invertebrates
  • Used to increase sensitivity (ability to capture light) increase aperture
  • To increase resolution (grain of image), increase aperture, lens size, increase number of photoreceptor cells
  • Includes: compound eyes, camera eyes: vertebrates and cephalopods
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15
Q

Compound eyes

A

Compound eyes cannot detect small or distant objects but provide a wider field of vision; raid recovery of retinal cells 6x faster than ours, so excellent motion detectors

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16
Q

Camera Eyes

A

Camera eyes; iris controls size of pupils, amount of light reaching retina – light enters through the pupil, and lens changes shape for focus – vitreous gel is translucent to let light through, cornea protects and retina contains photoreceptor cells and sends visual info to brain; macula and fovea are central region of retina and this is where most rods and cones are found
• Best sensitivity and resolution for larger animals; distance and direction
- Found in vertebrates and cephalapods

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17
Q

Eye Size

A

Big animal, big eyes

• Dark environment has bigger eyes (up to a point) – down to 1000m, small eyes below this

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18
Q

Quit point

A
  • Light intensity at which animals stop relying on vision in favour of other senses
  • Influenced by amount of light available and mode of life
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19
Q

Senses used by: Tropical megabats (flying foxes)

A
  • Eat fruit, nectar at dawn and dusk
  • Rely on sight, not echolocation
  • Relative big eyes
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20
Q

Senses used by: Microbats

A
  • Small eyes and big ears
  • Use echolocation for spatial orientation while flying at night
  • Only those that feed on flying insects use echolocation to capture prey
  • Others use odour, sounds produced by their prey, vision and in the case of vampire bats – infrared
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21
Q

Binocular vs monocular vision

A

o Predators: forward directed eyes
- Binocular vision: overlapping fields, 3D
- Restricts field of view
- Provides focus on prey
o Herbivores: lateral eyes
- Monocular vision: can see behind
- Can also see behind and around even with heads down
- Can see 3D vision
• Looking first with one eye and then the other

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22
Q

Pupils

A

o Adjustable aperture that lets light in
o Round in most animals, especially diurnal
o Slit shaped pupils
- Nocturnal animals that are also active in day (Ex: cats)
- Prevent damage to retina in bright light because can close more
- Gecko’s pupils zip up during day
o Goats and sheep: rectangular pupils that increase field of vision to 330 degrees

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23
Q

Neural processing

A

o Visual capabilities determined by the way the nervous system processes visual information
o Ex: summation in dark environments
o Some organisms have neural processing that enhances detection of certain shapes, some sensitive to movement

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24
Q

Visual communication: Bioluminescence

A 
o Production of an emission of light by living organism 
o Found:
- Widely in marine animals 
- Some fungi 
- Bacteria 
- Terrestrial invertebrates 
- In some animals, produced by symbiotic organisms 
o Uses of bioluminescence: 
- Camouflage 
• Blind or confuse predators 
• Reduce contrast 
- Mimicry 
• Mimic other bioluminescent species to catch them (ex: anglerfish) 
- Mate attraction
25
Q

Infrared and thermal systems - Charcoal beetles

A
  • Fire chasers, respond to infrared light (not to heat)
  • Can locate fire from more than 60KM away
  • Descend in large swarms while fire still hot, females lay eggs as soon as it stop burning
  • Larvae feed on recently burned wood – not yet decomposing
  • Avoid plant defenses
  • Used to descend on football stadiums when it was still legal to smoke
26
Q

Infrared and thermal systems - Pit Vipers and Boas

A
  • Thermal detectors in rostrum
  • Information processed by same part of brain that processes visual information
    • Therefore blind snake is just as efficient as non blind
    • If thermal detectors covered then snake less efficient
  • California ground squirrels use this: adults are resistant to venom, heat tails and then kick dirt in their face
27
Q

Electrical Signals

A

o Many organism of dark environments can detect electrical fields
o Effective range usually < length of animals (<1m)
o Expensive because high energy use
o Most effective in wet condition

28
Q

Detection of electrical discharges - Electrorecptors

A
  • Gel filled pores
  • Detect electrical discharge
  • Found in: cartilaginous fish (snout and head)
  • Sharks have ampullae of lorenzi
  • Some bony fish
  • Monotremes (snouts)
  • For prey detection and sometimes mating
29
Q

Detection of electrical discharges - Bees

A 
• Bees tend to be positive 
• Flowers ten to be negative 
•	When bee lands on flower:
- Pollen is transferred easily and quickly 
- Both are neutralized 
- May indicate nectar availability
30
Q

Sounding with Electricity

A
  • Some fish can use electricity for communication
  • Electrical fields produced by different
    species differ in shape, frequency and
    waveform
  • also variations with age, sex and slight
    individual variations
  • Elephant nose fish
  • Modify signal to show aggression or attract a mate
  • When two electric fish approach each other they may shift frequencies slightly
31
Q

Magnetic Signals

A
  • Magnetoreception: Ability to perceive the magnetic forces of earth
  • Many animals use it to provide info on location
  • Bees use magnetic signal; indicate location of food, orient comb, set circadian rhythms
  • In mammals
    • In captivity, woodmice: Orient activity toward home; Magnetoreception as a back-up
    • Microbats: Echolocaton for short, magneto for long distance
    • Ruminants (cow, deer): Orient north-south, except under powerlines
32
Q

Mechanical - Tactile

A
  • Very limited range
    Ex: Venus flytrap uses it to detect/catch prey
  • Impatiens: to release seeds
33
Q

Mechanical - Vibration

A
  • At short distances, movement of molecules through a substrate
  • Snakes detect substrate vibration better than sound, use inner ear
  • Spiders detect prey in their webs, mates and competitors: slit sensilla, mechanoreceptors in cuticle
    • Mechanoreceptors sense a physical deformation (pressure, touch, stretch, motion, sound vibration)
    • Ion channels linked to hairs OR internal structure cells like cytoskeleton
    • Bending/stretching alters permeability of ion channels  electrical signal
    • Mammals: Dendrites that wind around base of hairs detect gentle touch; Touch receptors deep in skin detect deeper pressure; Whiskers (cats…)
34
Q

Vibration in fish and amphibians

A

• Lateral line

  • Mechanosensory system in amphibians and fish
  • Made up of individual neuromasts
  • Made up of hair cells
  • Described as a “distant touch”
  • Used to detect predator, prey, inanimate objects
  • Used in schooling: Blind fish school
35
Q

Vibration in insects

A

• Commonly used for communication, predator detection
• Detected through mechanoreceptors:
- Trichoform sensilla
- Campaniform sensilla in legs, behind primary wings …
- Johnston’s organs: sensory organs involving hairs in antennae
• Ex: treehopper nymphs call mother through vibrational signals
• Ex: tree cutter ants call in their buddies through vibrational signals

36
Q

Mechanical - Sound

A
  • Second to light in providing detailed information at a distance
  • Less directional
  • BUT can be used in a dark or cluttered environment
  • Two parameters
    • Intensity (loudness, amplitude)
    • Pitch (frequency of waves)
37
Q

Infrasound

A 
<20Hz
• Low frequency 
• Long-distance 
• Bends around obstacles 
• Used by whales, rhinos, hippos, elephants, giraffes and okapi 
• Used by homing pigeons and other birds
38
Q

Audible sound

A 
20 Hz – 20 kHz 	
• What humans hear 
• Mid frequency 
• Intermediate distance 
• Somewhat obstructed by barriers
39
Q

Ultrasound

A 
>20 kHz 
• Highest frequency 
• Short-distance 
• Does not bend around objects 
• Used by bats to echolocate 
• Detected by insects prey to bats 
• Dogs, some fish etc. 
• Ultrasound speakers to frighten rodents, insects etc.
40
Q

Echolocation

A
  • Using ultrasound
  • Toothed whales, dolphins, porpoises, bats, shrews, cave-dwelling birds
  • To orient and capture prey
  • Energy expense reduced if coordinated with breath, movement
  • May be insensitive to own sound (close ear, detect only echo)
41
Q

Echolocation in microbats

A
  • CF - Constant frequency (sometimes QCF, nearly constant frequency, a very narrow bandwidth):
    o Good for detection of an echo
    o Good for detection of motion
  • FM (frequency modulated or frequency sweep that goes from high to low, broad bandwidth):
    o Better for localization of the sound since: provide time markers, information on size and texture
  • Mixed call with a CF and a FM
  • Bats that forage in two habitats may switch between signals
  • Shift frequencies when flying around other bats (to avoid jamming)
  • Whispering (basbastelle) bats: very quiet to avoid alerting prey
  • Not used for communication: for that bats use auditory range
42
Q

Bats that fly in open spaces

A
  • Insectivorous
  • Use long pulses of constant, fairly low frequency to scan
  • May switch to higher frequencies once prey detected
43
Q

Bats that forage for aerial insects near edges of the ground, water or forests (a background cluttered environment)

A
  • Have to distinguish b/w prey and background
  • Use a mixed signal
  • CF to detect prey
  • FM to locate prey and navigate
44
Q

Bats flying in highly cluttered space (ex: a forest)

A
  • Have greater problems with overlap b/w background and food
  • Aerial feeders use FM, CF or mixed (CF to detect and FM to zero in)
  • Use other types of information to find prey
45
Q

Echolocation in Dolphins

A
  • Clicks: Ultrasound, Audible sound

- Can detect: Single fish 9m away with ultrasound, School of fish further away with audible sound

46
Q

Chemical signals: Taste and smell

A
  • Used to alert organism, for specific information only
  • Smell: signal travels slowly and is replaced slowly
    • Number of chemicals is considerable
    • Difficult to detect the direction
  • Taste: direct
47
Q

Taste and Smell in Terrestrial animals

A
  • Taste mediated by contact chemoreceptors
  • Smell mediated by receptors that detect volatile chemicals

unclear in aquatic animals

48
Q

Chemoreceptors

A

• General: info about total solute concentrations (ex: osmoreceptors in mammalian brain stimulate thirst)
• Specific: info about specific chemicals
- Chemicals are detected by binding to receptor proteins
- Specific receptor can be specific for one chemical
- Other specific receptors can bind to a range of chemicals
Ex: humans have 10X as many distinguishable smells as types of receptors

49
Q

Perception of taste and smells - Fish

A
  • Extremely sensitive to dilute amounts of chemicals
  • Used to find food, home, mate, communicate
  • Smell: reception through nose
  • Taste associate with mouth, barbells (whiskers)
50
Q

Perception of taste and smells - Snakes and Other Reptiles

A

Three well developed chemical senses

1) nasal for most volatile chemicals
2) vomeronasal (Jacobson’s organ) for less volatile
3) taste for non-volatile (taste)
- Some overlap: an airborne odour will be detected by nose, then tongue…

51
Q

Vomeronasal organ detects pheromones

A
  • Many non-primate mammals and amphibians also have vomeronasal
  • Pheromones are chemicals excreted by individuals that affects members of same species
  • Vomeronasal requires direct contact with source of odour
  • Send signal to hypothalamus; affects reproductive behaviour and aggression
52
Q

Chemical used varies with habitat

A

Aquatic:
• Polar since these dissolve well in water
• Often large Terrestrial species:
• Less polar (but still somewhat polar to bind with chemoreceptor)
• Generally smaller molecules
• More volatile if they are to be airborne (ex: alcohols)
• Those that are detected from the substrate are less volatile, more polar (ex: organic acids)

53
Q

Chemical Signals vary with Function

A
  • Sex attractants: species-specific, relatively long so they stick around, not so long that they are not at all volatile
  • Alarm pheromones
    • Fairly small, disperse quickly
  • Sex pheromones in fish can be waste products, including bile, salts and hormones
  • Specificity may be determined by the ratios of the various components
54
Q

Chemical communication in silkworm moths

A
  • Female attracts male with bombykol pheromone
    • Species specific
  • Male antennae designed to detect small amounts
  • Male flies upwind when he detects bombykol in order to find the female
  • Bombykol amounts are too small to be detectable to most predators
55
Q

Chemical communication in fish

A
  • Small fish release purine-based alarm pheromones from skin during damage
  • When they detect the pheromone, the small fish engage in anti-predator behaviour
  • Similar sized fish of different species sensitive to each other’s pheromones (mutualism)
56
Q

Multi-channel communication

A

o Commonly more than one sense used

o Even in a single communication may involve multiple channels

57
Q

Drosophila courtship: Example of Multi-channels

A
  • Step 1: visual recognition of female by male
  • Step 2: olfactory detection of female by male
  • Step 3: male touches female
  • Step 4: female release pheromones (olfactory)
  • Step 5: male vibrates wings (vibration and auditory)
58
Q

Bee communication: Example of Multi-channels

A

Some social bees communicate with hive-mates to indicate location of food:
• Scaptotrigona postica: Marks the route with a pheromone; Leads recruits to source
• Melipona: Zigzag dance with partial leadings; Gives information on direction; Activity level and sound gives distance and value: more rapid means better and closer
• Apis florea (dwarf honey bee); Round dance for close sources-no direction; Waggle dance for distant sources; Direction points at source during waggle; Note: hive horizontal
• Apis (other honey bees); Same as for dwarf honey bees except hive is vertical so direction adjusted; Angle relative to vertical surface of hive the same as horizontal angle of food from sun

59
Q

How do we know the bee dance works?

A

• Bees can be seen to follow direction
• Bees can be tricked into following misleading directions
- If partially blind bee orients towards bright light instead of sun, bees make same mistake
- Bees will follow direction of fake bee

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