overview make strong fields for hunting (rare) make weak fields for other uses (more common) ...

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

+

-

-+

-

+

-

+

-

+

-

+

-

+

-

+

-

; 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

!