overview make strong fields for hunting (rare) make weak fields for other uses (more common) ...
TRANSCRIPT
OverviewOverviewMake Strong Fields for
hunting (rare)Make Weak fields for
other uses (more common)
Don’t make electrical fields, but sense them (very common).
Make Strong Fields for hunting (rare)
Make Weak fields for other uses (more common)
Don’t make electrical fields, but sense them (very common).
Electricityfor Hunting
Strongly Electric Fish
Electricity made using muscles or nerves
TorpedoRay
Electro-plaques
Tells how many electrons are moving through the circuit.
Tells how hard the electrons are being pushed.
12 V, 1 amp
24 V
4 X 12 = 48 V, 1 amp
1 Amp, 12 V
4 Amps, 12 V
Batteries 12 V and 1 Amp
36 V4 Amp
Torpedo Ray
Bottom Side!
Electro-plaques
Torpedo Ray
Stacking For Volts
+
-
-+
-
+
-
+
-
+
-
+
-
+
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+
-
; Multiple stacks for Amps
Electric Eel
6.000 electroplaques500 volts and 1 amp = 500 watts
OverviewOverviewMake Strong Fields for
hunting (rare)Make Weak fields for
other uses (more common)
Don’t make electrical fields, but sense them (very common).
Make Strong Fields for hunting (rare)
Make Weak fields for other uses (more common)
Don’t make electrical fields, but sense them (very common).
Fish that make Weak FieldsFish that make Weak Fields
Active Electricity for
Locating preyAvoiding predators
NavigationCommunication
Active Electricity for
Locating preyAvoiding predators
NavigationCommunication
Weakly Electric FishWeakly Electric Fish
MormyridsMormyrids
14 Percent of all fish species = Mormyrids
Red October Nimitz
“Ping”
Sound waves sent out by the Red October bounce off the Nimitz and back to the Red October. Sonar operators on the Red October hear the reflected sound and know that the Nimitz is there.
ActiveSonar
“gotcha”ActiveElectricalSenses
An electrical field sent out by special organs in the Red Fish is distorted by the other fish. Electrical field detectors on the Red Fish detect the distortion and know that the other fish is there. Finds prey and predators.
Active Electricity for
Locating preyAvoiding predators
NavigationCommunication
Active Electricity for
Locating preyAvoiding predators
NavigationCommunication
ActiveElectricalSenses
Rock
Why to Electric Eels and Mormyrids have such weird fins?
The elephant fish sets up a nice symmetrical electrical field using it’s electrical organ. When anything enters the field, the field is distorted and the fish can sense the change.
Active Electricity for
Locating preyAvoiding predators
NavigationCommunication
Active Electricity for
Locating preyAvoiding predators
NavigationCommunication
Electricity forCommunication
OverviewOverviewMake Strong Fields for
hunting (rare)Make Weak fields for
other uses (more common)
Don’t make electrical fields, but sense them (very common).
Make Strong Fields for hunting (rare)
Make Weak fields for other uses (more common)
Don’t make electrical fields, but sense them (very common).
Passive Electricity for
Locating preyAvoiding predators
NavigationCommunication
Passive Electricity for
Locating preyAvoiding predators
NavigationCommunication
All animalsmake a weak electrical field
Red October
Nimitz
Sound from the engines and propeller of the Nimitz are detected by sonar operators on the Red October. When they hear the sound they know the Nimitz is there.
PassiveSonar
An electrical field produced by normal muscle and nerve activity in the green fish is detected by electrical sensors on the Red Fish.
PassiveElectricalSenses
Hammerheads and Stingrays
Fish That Sense Electricity: It isn’t just for exotic species
Dermis
Epidermis
Ampullary Organfor sensing electrical fields
Sharks
Moving a wire through a magnetic field produces
an electrical current
Sensors on Sharks
= Opening of Ampullae
= Lateral Line
= Canal between Ampullae
Canals are
full
of
Conductiv
e jelly
!
Shark Navigation
Electricity Highlights
• Some fish use muscle and nerves to make strong fields for killing prey
• Some fish just sense electrical fields– Passive electrical senses – detects other animals for hunting or
escape• Other fish make weak fields for navigation or
communication• Communication: Mormyrids zap messages to each other
and receive them• Navigation
– Active electrical senses: zap out a field and look for interference• Sensors in bony fish = ampullary organs• Sensors in sharks = conductive canals, Ampullae of
Lorenzini
The Lateral Line
Ampula
Cupola
LateralLineCanal
CupolaHair Cells
Hair Cells
Canal to skin surface
Crista in Ear Neuromast in Lateral Line
Ampula
Cupola
LateralLineCanal
CupolaHair Cells
Hair Cells
Canal to skin surface
Crista in Ear Neuromast in Lateral Line
Water Movement
Neuromasts
Muscle
Dermis
Epidermis
Pore
Muscle
Dermis
EpidermisPoreScaleWater
Water Movement
FreeNeuromasts
Super SensitiveNo “Filter”
= Lateral Line Pores
= Exposed Neuromasts
Tilapia: The lateral line is interrupted to avoid the fin
Flounder: The lateral line goes around the fin.
Placements avoid fins, but also
reveal the purpose of the Lateral
Line
Schooling
Protection
Flying Fish: The lateral line is on the bottom of the fish so that it can sense what is beneath.
Prey Detection
Frogfish
Frog Fish: The lateral line goes along the top of the fish so that it can sense what is above.
Killifish
The struggling bug makes ripples that the killifish detects with free neuromasts
Antarctic Pagothenia
Antarctic Pagothenia
Lateral line specially tuned to shrimp vibrations
Navigation
Blind Cavefish
Lateral Line Highlights• Detects movements in the water• Canal connected to surface by pores• Movement of water detected my neuromasts• Neuromasts look like cristae (ears)• Neuromasts may be exposed, but they are
extremely sensitive: not for rough water• Lateral line and neuromasts are positioned
depending on the needs of the fish• Lots of uses: Schooling, prey detection,
predator avoidance, navigation
Semicircular Canals Third canal (horizontal) not visible
Ampullae
FishEar
Right side Up FishOtolith
Upside Down Fish
Otolith bending hairs on hair cells
Hairs on hair cells straight
Focusing in MammalsLens shape changes
Side Views Front View
Near
Far
Focusing in FishMuscle pulls on lens
DaytimeCones in frontRods Shaded
Light
NightRods in FrontNo ShadingCones in Back
Light
Smell vs. Taste?
• Nose
• Sensors in the Olfactory Epithelium
• Many uses, including food location
• Nose
• Sensors in the Olfactory Epithelium
• Many uses, including food location
• Mouth, & many places
• Taste buds SCC
• Primarily for feeding
• Mouth, & many places
• Taste buds SCC
• Primarily for feeding
Olfactory EpitheliumCiliated Cells
Molecules Whooshing by in the Water
Nerves to the brain
• Amino acids: The building blocks of protein. Some amino acids are more stimulatory than others.
• Steroids: Some fish are highly sensitive to hormones especially those related to reproductive activities (see below).– Prostaglandins: Released by
female fish upon ovulation.
What Can They Taste ?
• sweet, sour, bitter, salty, uma • Amino acids• Steroids: Sex hormones• Organic acids and nucleotides: • Carbon Dioxide: ??• Peptide toxins: Like marine puffer
toxin
Solitary Chemoreceptor Cells: SCC
Dispersed on external surface of fish as well as on gills and in the oral cavity.
These cells are sensitive to amino acids in some species but not others.
They are especially adept at detecting fish mucus and some organic acids.
• Eggs: found in a redd
• Alevin: fry with yolk
• Parr: Fingerlings in fresh water, black bars
• Smolt: Fingerling ready for the sea, silver
• Adult: In the sea
Does not die, returns to the sea
Homing Theories
•Imprinting: Salmon smell the stream
•Pheromone: Salmon smell their kin
•Which is right?
“zap”ActiveElectricalSenses
An electrical field sent out by special organs in the Red Fish is distorted by the other fish. Electrical field detectors on the Red Fish detect the distortion and know that the other fish is there.
An electrical field produced by normal muscle and nerve activity in the green fish is detected by electrical sensors on the Red Fish.
PassiveElectricalSenses
Sensors on Sharks
= Opening of Ampullae
= Lateral Line
= Canal between Ampullae
Canals are
full
of
Conductiv
e jelly
!