What is a Fish?

1
Sensory Perception
Vision Olfaction Hearing mechanoreception Electr
oreception Magnetoreception
2
Senses
Physical Quantity Sense Organ
Sound Ears
Water flow Lateral line
Chemicals Taste Buds/Nose
Electricity Ampullae of Lorenzini
Magnetic Fields Nose ????
Light Eyes

3
Acoustico Lateralis System

• Equilibrium
• Hearing
• Mechanoreception

Hair sensory cells
4
Sensory Hair Cells
5
Hearing in Fishes

• Fish have ears
• Otoliths detect particle motion
• Swimbladder can act as pressure transducer

6
What is Sound?

• Sound is a mechanical vibration that propagates
  through an elastic medium such as air or water.
• Sound travels as waves of oscillating particles
  accompanied by increases and decreases in the
  ambient pressure.
• Sound propagates along the axis of particle
  vibration.

7
Ear Morphology
8
Fish hearing is generally low-frequency
9
(No Transcript)
10
Cyprinidae
11
American Shad Audiogram
12
Ultrasonic detection by american shad.
Classical Conditioning Example of cardiac
response followed by electric shock
13
Ultrasonic sound detection by American
Shad Auditory Brain Response
14
Sound Production
Swimbladder of the toadfish, Opsanus sp.  Sonic
muscles can be seen on the lateral walls.
Batrachoididae Oyster toadfish Opsanus tau
15
Ecology of Sound Production
             
Sound produced by spawning aggregation of
sciaenids
16
Lateral Line
Neuromasts groups of hair cell w/gelatinous
cupule
17
Hydrodynamic Stimuli

• Water currents from flows (rheotaxis)
• Schooling/predator avoidance
• Active hydrodynamic imaging
• Passive hydrodynamic imaging
• Courtship
• Subsurface feeding

18
Flows produced by organisms
19
Lateral line shapes
20
Electroreception
Elasmobranchs Teleosts Low frecuency AC - DC
Teleosts High frequency AC
21
Electroreceptors
22
Ampullae de Lorenzini
Dogfish can detect a flounder buried 15 cm deep
(1 mV/Km)
23
(No Transcript)
24
(No Transcript)
25
Electrical fishes
26
Electric Organ Discharge (EOD)

• Modified muscle cells to create EOD

27
Brachyhypopomus spp. EOD
28
Magnetoreception

• Elasmobranchs
• Hammerhead shark schools
• Laboratory experiments with rays
• Teleosts
• Magnetite found in Salmon and Tuna

29
Magnetoreception
30
Induced Electric Field

• Currents in ocean flowing through earths
  magnetic field generate currents from lt5 nV/cm to
  500 nV/cm.
• Suspected that eels use these currents, but not
  clear if they are sensitive enough to electrical
  fields.
• Stingrays can sense fields as low as 5 nV.cm

31
At ambient magnetic field of 0.5 gauss, a
swimming speed of 1 cm/s would produce a
threshold stimulus of 5 nV/cm. This has yet to be
proven.
32
Magnetite in Nose (Trout)

1. Bacteria containing magnetite (not from the
   trout).
2. Olfactory epithelium. Red dot with arrow is
   putative magnetite.
3. Bright field (left) and dark field (right) TEM of
   dot from b.
4. Energy dispersive analysis of x-rays from
   crystal. Shows presence of iron (Cu is from
   copper screen, Pb and U from TEM stains).

Walker, Diebel, Haugh, Pankhurst, Montgomery,
Green. 1997. Structure and function of the
vertebrate magnetic sense. Nature. 390 371-376.
33
Olfaction
34
(No Transcript)
35
(No Transcript)
36
Taste Buds
37
Vision
38
Photoreceptor cells

• Rods
• Sensitive at low light levels
• Present in all fishes
• Cones
• Sensitive at high light intensity
• Some elasmobranchs and most fishes
• Red cones (600nm)
• Green cones (530nm)
• Blue cones (460nm)
• Ultraviolet cones (380nm)

39
Electromagnetic Wavelengths
40
(No Transcript)
41
Rod maximum absorption
42
Visual Acuity
Determined by eye aperture and photoreceptor
density. Acuity increases as size increases.