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.
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
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
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)
5
Q
Channels of information transfers - Mechanical Energy and Force
A
- Sound and sonar (bats)
- Pressure
- Touch and vibration
- Gravity
- Inertia
6
Q
Channels of information transfers - Chemical
A
- Taste
- Smell
- Humidity
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
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
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
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
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)
12
Q
Photoreceptor: Intensity detector
A
- May be heat detectors
Ex: bacteria and archaea; too small to detect direction - Photoreceptor proteins; bacteriorhodpsin…
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…)
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
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
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
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
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
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
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
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
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
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
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
Infrared and thermal systems - Charcoal beetles
- 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
Infrared and thermal systems - Pit Vipers and Boas
- 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
Electrical Signals
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
Detection of electrical discharges - Electrorecptors
- 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
Detection of electrical discharges - Bees
```
• 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
Sounding with Electricity
- 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
Magnetic Signals
- 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
Mechanical - Tactile
- Very limited range
Ex: Venus flytrap uses it to detect/catch prey
- Impatiens: to release seeds
33
Mechanical - Vibration
- 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
Vibration in fish and amphibians
• 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
Vibration in insects
• 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
Mechanical - Sound
- 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
Infrasound
```
<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
Audible sound
```
20 Hz – 20 kHz
• What humans hear
• Mid frequency
• Intermediate distance
• Somewhat obstructed by barriers
```
39
Ultrasound
```
>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
Echolocation
* 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
Echolocation in microbats
- 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
Bats that fly in open spaces
* Insectivorous
* Use long pulses of constant, fairly low frequency to scan
* May switch to higher frequencies once prey detected
43
Bats that forage for aerial insects near edges of the ground, water or forests (a background cluttered environment)
* Have to distinguish b/w prey and background
* Use a mixed signal
* CF to detect prey
* FM to locate prey and navigate
44
Bats flying in highly cluttered space (ex: a forest)
* 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
Echolocation in Dolphins
- Clicks: Ultrasound, Audible sound
| - Can detect: Single fish 9m away with ultrasound, School of fish further away with audible sound
46
Chemical signals: Taste and smell
- 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
Taste and Smell in Terrestrial animals
* Taste mediated by contact chemoreceptors
* Smell mediated by receptors that detect volatile chemicals
*unclear in aquatic animals*
48
Chemoreceptors
• 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
Perception of taste and smells - Fish
- 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
Perception of taste and smells - Snakes and Other Reptiles
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
Vomeronasal organ detects pheromones
- 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
Chemical used varies with habitat
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
Chemical Signals vary with Function
- 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
Chemical communication in silkworm moths
- 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
Chemical communication in fish
- 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
Multi-channel communication
o Commonly more than one sense used
| o Even in a single communication may involve multiple channels
57
Drosophila courtship: Example of Multi-channels
- 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
Bee communication: Example of Multi-channels
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
How do we know the bee dance works?
• 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
