Fish BehaviorFish Behavior

Animal BehaviorAnimal Behavior Action or reaction to stimuli Happens in the brain (non-motor) and can be

manifested through muscular response, but often involves both

There can be a temporal component to the actual behavior (learning, e.g. feed training)

Short-term trigger for behavior, or effect on the organism

Long-term evolutionary significance/adaptation: behavior is selected for.

Animals behave in ways that maximize their fitness

Action or reaction to stimuli Happens in the brain (non-motor) and can be

manifested through muscular response, but often involves both

There can be a temporal component to the actual behavior (learning, e.g. feed training)

Short-term trigger for behavior, or effect on the organism

Long-term evolutionary significance/adaptation: behavior is selected for.

Animals behave in ways that maximize their fitness

Genetic vs. Environmental Factors

Genetic vs. Environmental Factors

Nature/nurture? On-going debate Behaviors have phenotypic variation:

studies on problem solving Due in part to genetic propensity: “ability”

to learn Due in part to environmental pressures and

variability The two: genes and environment, work

together Innate behavior: less subject to

environmental variation. Developmentally fixed

Nature/nurture? On-going debate Behaviors have phenotypic variation:

studies on problem solving Due in part to genetic propensity: “ability”

to learn Due in part to environmental pressures and

variability The two: genes and environment, work

together Innate behavior: less subject to

environmental variation. Developmentally fixed

Innate BehaviorFixed Action Patterns

Innate BehaviorFixed Action Patterns

Fixed Action Patterns: stereotypical innate behavior.

The organism will carry it out almost no matter what, even if it does not seem appropriate.

These are all part of a category of behaviors very important to survival and/or fitness.

Fixed Action Patterns: stereotypical innate behavior.

The organism will carry it out almost no matter what, even if it does not seem appropriate.

These are all part of a category of behaviors very important to survival and/or fitness.

Fixed Action Patterns - Example

Fixed Action Patterns - Example

Male three-spined stickleback: attacks other males with red bellies – attacks anything red

Male three-spined stickleback: attacks other males with red bellies – attacks anything red

Innate behavior Innate behavior

Brood parasitism is a classic example (Cichlids cuckoo catfish)

Fish behaving badly!

Ability to confront novel stimuli, learn about them, and adjust behavior is indicative of intelligence and self awareness. Intelligence is ‘costly’: brain development, parental investment, etc.

Brood parasitism is a classic example (Cichlids cuckoo catfish)

Fish behaving badly!

Ability to confront novel stimuli, learn about them, and adjust behavior is indicative of intelligence and self awareness. Intelligence is ‘costly’: brain development, parental investment, etc.

Cuckoo catfishSynodontis punctatus

Blue Victoria mouthbrooderHaplochromis nubilus

LearningLearning Change in behavior based on experience

Maturation is behavior change based largely on ability due to development (e.g., use of tool)

Habituation Loss of responsiveness due to repetition

Imprinting Learning in a critical time period (tightly

correlated with innate behavior) (e.g., salmon imprint on stream)

Conditioning: Pavlov Associating a stimulus with punishment or

reward (can also be trial and error) (visual experiments)

Change in behavior based on experience Maturation is behavior change based largely on

ability due to development (e.g., use of tool) Habituation

Loss of responsiveness due to repetition Imprinting

Learning in a critical time period (tightly correlated with innate behavior) (e.g., salmon imprint on stream)

Conditioning: Pavlov Associating a stimulus with punishment or

reward (can also be trial and error) (visual experiments)

Halichoeres garnotiYellowhead wrasse

Use of a rock as an anvil

Associative learning/conditioning

Associative learning/conditioning

Associating one stimulus with another Pavlov: classical conditioning.

Associating an arbitrary stimulus with reward or punishment

Operant conditioning: learning through trial and error. BF Skinner’s experiments. This has formed the basis for much animal training.

Classical and operant conditioning often work together

Associating one stimulus with another Pavlov: classical conditioning.

Associating an arbitrary stimulus with reward or punishment

Operant conditioning: learning through trial and error. BF Skinner’s experiments. This has formed the basis for much animal training.

Classical and operant conditioning often work together

CognitionCognition

Problem solving studies Consciousness and awareness The connection between nervous

system function and behavior Spatial orientation and mapping

Migration: Piloting, orientation (directional headings), navigation (relative location)

The role of learning in migration

Problem solving studies Consciousness and awareness The connection between nervous

system function and behavior Spatial orientation and mapping

Migration: Piloting, orientation (directional headings), navigation (relative location)

The role of learning in migration

MigrationMigration

Spatial orientation and mappingMigration: Piloting, orientation (directional headings), navigation (relative location)

The role of learning in migration

(magnetite, light, etc.)

Spatial orientation and mappingMigration: Piloting, orientation (directional headings), navigation (relative location)

The role of learning in migration

(magnetite, light, etc.)

Clownfishes / Anemones

Symbiosis

Behavioral ecologyBehavioral ecology

Animals behave in ways that maximize their fitness

Examples: Reproductive behavior = more

successful offspring

Feeding behavior = maximum energy gain

Animals behave in ways that maximize their fitness

Examples: Reproductive behavior = more

successful offspring

Feeding behavior = maximum energy gain

Fish BehaviorsFish Behaviors

• Migration • Shoaling • Feeding • Aggression • Resting • Communication  

• Migration • Shoaling • Feeding • Aggression • Resting • Communication  

Fish Migration Fish Migration

• Fish migrations are usually round-trip • Reasons for migration – Food gathering – Temperature adjustment – Breeding

• Fish migrations are usually round-trip • Reasons for migration – Food gathering – Temperature adjustment – Breeding

Timing of migrationsTiming of migrations

– Annual – Daily – generational

– Annual – Daily – generational

Classification of Fish Migration Classification of Fish Migration

Diadromous – Travel between sea & fresh water

– Anadromous – most of life at sea, breed in fresh water – Catadromous – most of life in fresh water, breed at sea – Amphidromous – migrate between water types at some stage other than breeding

• Potamodromous – Migrate within a fresh water system

Ocenodromous – Migrate to different regions of the ocean

Diadromous – Travel between sea & fresh water

– Anadromous – most of life at sea, breed in fresh water – Catadromous – most of life in fresh water, breed at sea – Amphidromous – migrate between water types at some stage other than breeding

• Potamodromous – Migrate within a fresh water system

Ocenodromous – Migrate to different regions of the ocean

Orientation During Migration

Orientation During Migration

• Orientation to gradients of temperature, salinity, and chemicals • Orientation by the sun • Orientation to geomagnetic and geoelectric fields

• Orientation to gradients of temperature, salinity, and chemicals • Orientation by the sun • Orientation to geomagnetic and geoelectric fields

Disadvantages of Migrations

Disadvantages of Migrations

• Expenditure of energy – Most must store energy before migration • Risk from predation

• Expenditure of energy – Most must store energy before migration • Risk from predation

Adjustments Required Due to Migrations

Adjustments Required Due to Migrations

• Adjusting physiologically to new water conditions – Temperature – Light – Water chemistry

• Many migratory species are now rapidly declining due to changes caused by man

• Adjusting physiologically to new water conditions – Temperature – Light – Water chemistry

• Many migratory species are now rapidly declining due to changes caused by man

Fish Behavior & CommunicationFish Behavior & Communication

Comparison of Migrations • Some stream species migrate a few meters from feeding to spawning grounds • Some species travel hundreds of km just to spawn

Comparison of Migrations • Some stream species migrate a few meters from feeding to spawning grounds • Some species travel hundreds of km just to spawn

Fish Behavior & CommunicationFish Behavior & Communication

Shoals and Other Aggregations • Forms of fish grouping – Solitary – Shoal – School – Pod • Reasons for grouping – Traveling – Feeding – Dealing with predators – Reproduction

Shoals and Other Aggregations • Forms of fish grouping – Solitary – Shoal – School – Pod • Reasons for grouping – Traveling – Feeding – Dealing with predators – Reproduction

DefinitionsDefinitions

Shoal - any group of fishes that remains together for social reasons

School - a polarized, synchronized shoal (has coordinated, directed movements)

Shoal - any group of fishes that remains together for social reasons

School - a polarized, synchronized shoal (has coordinated, directed movements)

How do Schools Work?How do Schools Work?

Requires great deal of coordination among individuals in the school

Vision is primary sensory cue for coordinating movement

Use of optomotor reaction - individual movement is coordinated with movement of some other visually distinctive object - e.g., a spot or a stripe

Requires great deal of coordination among individuals in the school

Vision is primary sensory cue for coordinating movement

Use of optomotor reaction - individual movement is coordinated with movement of some other visually distinctive object - e.g., a spot or a stripe

Functions of Schooling Behavior

Functions of Schooling Behavior

Hydrodynamic efficiency

Reduced predation risk

Feeding

Reproduction

Hydrodynamic efficiency

Reduced predation risk

Feeding

Reproduction

Functions of Schooling Behavior

Functions of Schooling Behavior

Hydrodynamic efficiency

individuals obtain reduction in drag

by following in “slip-stream” of

neighbors

limited evidence in support of this

Hydrodynamic efficiency

individuals obtain reduction in drag

by following in “slip-stream” of

neighbors

limited evidence in support of this

Functions of Schooling Behavior

Functions of Schooling Behavior

Reduced predation risk creates patchy distribution of prey -

large areas with no prey once school is found, individual risk of

being captured is reduced by dilution confusion of prey by protean displays,

encirclement, other behaviors

Reduced predation risk creates patchy distribution of prey -

large areas with no prey once school is found, individual risk of

being captured is reduced by dilution confusion of prey by protean displays,

encirclement, other behaviors

Functions of Schooling Behavior

Functions of Schooling Behavior

Feeding increases effective search space for

the individual (more eyes, separated by greater distance)

coordinated movements to help break up schools of prey - analogous to pack behavior in wolves - by tunas, jacks

Feeding increases effective search space for

the individual (more eyes, separated by greater distance)

coordinated movements to help break up schools of prey - analogous to pack behavior in wolves - by tunas, jacks

Functions of Schooling Behavior

Functions of Schooling Behavior

Reproduction increases likelihood of finding a mate facilitates coordination of

preparedness (behavioral and pheromonal cues)

facilitates arriving at right spawning site at right time

Reproduction increases likelihood of finding a mate facilitates coordination of

preparedness (behavioral and pheromonal cues)

facilitates arriving at right spawning site at right time

Fish Behavior & CommunicationFish Behavior & Communication

Shoaling • A social grouping of fish • Occurs throughout life in about 25% of fish species • Half of all fish shoal at some time

Benefits of Shoaling • Gives a predator many moving targets – Confuses predators – Increases chances at the individual level

– Increases food finding ability • Keeps potential mates in close proximity

Shoaling • A social grouping of fish • Occurs throughout life in about 25% of fish species • Half of all fish shoal at some time

Benefits of Shoaling • Gives a predator many moving targets – Confuses predators – Increases chances at the individual level

– Increases food finding ability • Keeps potential mates in close proximity

Fish Behavior & CommunicationFish Behavior & Communication

Pods • Tightly grouped school • Move as a single unit (including making quick turns) • Makes the school appear like one large organism – Protection from predators

Pods • Tightly grouped school • Move as a single unit (including making quick turns) • Makes the school appear like one large organism – Protection from predators

Liabilities of Grouping Behavior

Liabilities of Grouping Behavior

• Increased likelihood of disease & parasite transmission

• Becoming more conspicuous to some predators – Harvested more easily by man

• Increased likelihood of disease & parasite transmission

• Becoming more conspicuous to some predators – Harvested more easily by man

Feeding BehaviorFeeding Behavior

• Morphology is often a key to feeding behavior – many fish have specialized habits • Actual feeding may depend on what is available

• Optimal foraging – Take whatever is closest, as long as it is suitable food – Highest quality of food for the least amount of effort

• Morphology is often a key to feeding behavior – many fish have specialized habits • Actual feeding may depend on what is available

• Optimal foraging – Take whatever is closest, as long as it is suitable food – Highest quality of food for the least amount of effort

Optimal ForagingOptimal Foraging

• All else being equal, take the largest prey • Don’t choose prey that takes more energy than it provides • Be in a habitat that provides the type of food you are looking for

• All else being equal, take the largest prey • Don’t choose prey that takes more energy than it provides • Be in a habitat that provides the type of food you are looking for

Feeding BehaviorFeeding Behavior

Example - Sunfish, provide predator with prey of different sizes and different densities, fish respond by foraging optimally (taking the most energetically rich prey under the appropriate conditions)

Example - Sunfish, provide predator with prey of different sizes and different densities, fish respond by foraging optimally (taking the most energetically rich prey under the appropriate conditions)

Risk Sensitive ForagingRisk Sensitive Foraging• Foraging is sometimes restricted

because of undo risk – It does not make sense to look for prey where you will become the prey – Must balance energy gain possibility with risk of obtaining the energy

• Foraging is sometimes restricted because of undo risk – It does not make sense to look for prey where you will become the prey – Must balance energy gain possibility with risk of obtaining the energy

Finding FoodFinding Food

• Visual detection – Diurnal feeders – Means being in the open in bright light

• Olfaction – Common in bottom dwelling species

• Taste

• Visual detection – Diurnal feeders – Means being in the open in bright light

• Olfaction – Common in bottom dwelling species

• Taste

Aggressive BehaviorAggressive Behavior

• Direct charges – Often includes biting

• Ritualistic displays – Modified swimming – Flaring gill covers – Color changes – Threatening movements

• Direct charges – Often includes biting

• Ritualistic displays – Modified swimming – Flaring gill covers – Color changes – Threatening movements

Reasons for Aggressive Behavior

Reasons for Aggressive Behavior

• Defense of territory – Usually connected with reproduction – Sometimes to keep food source • Defense of brood • Repelling competitors for mates

• Defense of territory – Usually connected with reproduction – Sometimes to keep food source • Defense of brood • Repelling competitors for mates

Resting Behavior Resting Behavior • Inactive state

• Some fish spend a large part of the day not doing anything • Many species change color patterns • Most fish rest on or near the substrate • Many fish have a specified time of day when resting takes place • Some fish never rest (Sleep swimming?)

– Must keep moving (sharks)

• Inactive state • Some fish spend a large part of the day not doing anything • Many species change color patterns • Most fish rest on or near the substrate • Many fish have a specified time of day when resting takes place • Some fish never rest (Sleep swimming?)

– Must keep moving (sharks)

CommunicationCommunication

Visual signals Auditory signals Chemical signals Electric signals

Visual signals Auditory signals Chemical signals Electric signals

SignalsSignals

Visual Signals • Most important communication signal • Large variety of signals – Different species use different “languages” – Some cues are recognized between species

Visual Signals • Most important communication signal • Large variety of signals – Different species use different “languages” – Some cues are recognized between species

How visual signals are produced

How visual signals are produced

• Types of coloring – Pigments • Colored compounds • Located in chromatophores – Mostly in skin, but also in eyes & organs • Controlled by hormones & nerves – Structural colors • Reflection of light

• Types of coloring – Pigments • Colored compounds • Located in chromatophores – Mostly in skin, but also in eyes & organs • Controlled by hormones & nerves – Structural colors • Reflection of light

Kinds of Pigments in FishKinds of Pigments in Fish

• Carotenoid pigments – Bright reds & yellow – Green when they overlie blue structural color

• Melanins – Dark red, brown, black

• Purines (guanine) – Colorless crystals responsible for some structural colors

• Carotenoid pigments – Bright reds & yellow – Green when they overlie blue structural color

• Melanins – Dark red, brown, black

• Purines (guanine) – Colorless crystals responsible for some structural colors

Purpose of Color PatternsPurpose of Color Patterns

• Thermoregulation – Probably not very significant

• Intraspecific communication • Evasion of predators

• Thermoregulation – Probably not very significant

• Intraspecific communication • Evasion of predators

Common Color PatternsCommon Color Patterns

• Red coloration • Poster colors • Disruptive colors • Countershading • Eye ornamentation • Lateral stripes • Polychromatism

• Red coloration • Poster colors • Disruptive colors • Countershading • Eye ornamentation • Lateral stripes • Polychromatism

Red ColorationRed Coloration

• Red fish are common • Cryptic color in low light • Blends in with red algae • Used in spawning fish – Recognized at short distances – Does not attract predators at long distance

• Red fish are common • Cryptic color in low light • Blends in with red algae • Used in spawning fish – Recognized at short distances – Does not attract predators at long distance

• Bright, complex color patterns – Some fish use this to advertise when protecting territories – May serve to signal shoal – In some cases it may be used for predator avoidance - Blending into a complex background – Flash effect to avoid predators – May serve as a warning to others

• Bright, complex color patterns – Some fish use this to advertise when protecting territories – May serve to signal shoal – In some cases it may be used for predator avoidance - Blending into a complex background – Flash effect to avoid predators – May serve as a warning to others

• Disrupt the outline of the fish Disrupt the outline of the fish – Make them less visible – Make them less visible – Often associated with beds of – Often associated with beds of plants plants

Also known asAlso known as “protective “protective resemblance”resemblance”

• Disrupt the outline of the fish Disrupt the outline of the fish – Make them less visible – Make them less visible – Often associated with beds of – Often associated with beds of plants plants

Also known asAlso known as “protective “protective resemblance”resemblance”

• Being dark on top, light on bottom – Look like substrate from above – Look like water surface from below

• Being dark on top, light on bottom – Look like substrate from above – Look like water surface from below

Eye Ornamentation Eye Ornamentation

Disguising the eyeDisguising the eye

• • Minimize contrasting color Minimize contrasting color

• • Field of spots around eye to disguise pupil Field of spots around eye to disguise pupil

• • Eye lines that match pupilEye lines that match pupil

Emphasizing the eyeEmphasizing the eye

• • Pattern or colors in eye Pattern or colors in eye

• • Usually used for interspecific signalingUsually used for interspecific signaling

Disguising the eyeDisguising the eye

• • Minimize contrasting color Minimize contrasting color

• • Field of spots around eye to disguise pupil Field of spots around eye to disguise pupil

• • Eye lines that match pupilEye lines that match pupil

Emphasizing the eyeEmphasizing the eye

• • Pattern or colors in eye Pattern or colors in eye

• • Usually used for interspecific signalingUsually used for interspecific signaling

EyeEye Spots Spots EyeEye Spots Spots

• Usually at base of caudal fin Usually at base of caudal fin – Usually used to confuse – Usually used to confuse predators predators

• • Common in some fry Common in some fry – Sometimes used for species – Sometimes used for species recognitionrecognition

• Usually at base of caudal fin Usually at base of caudal fin – Usually used to confuse – Usually used to confuse predators predators

• • Common in some fry Common in some fry – Sometimes used for species – Sometimes used for species recognitionrecognition

LateLateral Strral Stripesipes LateLateral Strral Stripesipes

• Mid-lateral band usually Mid-lateral band usually

• • Best developed in schooling Best developed in schooling fish fish – Keep school oriented while – Keep school oriented while confusing predators confusing predators – Makes it hard to pick out – Makes it hard to pick out individualsindividuals

• Mid-lateral band usually Mid-lateral band usually

• • Best developed in schooling Best developed in schooling fish fish – Keep school oriented while – Keep school oriented while confusing predators confusing predators – Makes it hard to pick out – Makes it hard to pick out individualsindividuals

• Dominant members are often more Dominant members are often more brightly colored brightly colored – Makes it easier to attract mates – Makes it easier to attract mates – But makes them more conspicuous to – But makes them more conspicuous to predatorspredators

• Dominant members are often more Dominant members are often more brightly colored brightly colored – Makes it easier to attract mates – Makes it easier to attract mates – But makes them more conspicuous to – But makes them more conspicuous to predatorspredators

Auditory SignalsAuditory SignalsAuditory SignalsAuditory Signals

• Most fish produce sounds Most fish produce sounds

• • Uses for sound Uses for sound – Courtship singing (toadfish)– Courtship singing (toadfish)

– – Territorial defense Territorial defense – Signaling shoal– Signaling shoal

• Most fish produce sounds Most fish produce sounds

• • Uses for sound Uses for sound – Courtship singing (toadfish)– Courtship singing (toadfish)

– – Territorial defense Territorial defense – Signaling shoal– Signaling shoal

Sound ProductionSound ProductionSound ProductionSound Production

• Stridulation Stridulation – Rubbing hard surfaces together – Rubbing hard surfaces together – Low frequency sounds – Low frequency sounds

• • Vibration of swimbladder Vibration of swimbladder – Can give loud croaking – Can give loud croaking

• • Incidental to other activitiesIncidental to other activities

• Stridulation Stridulation – Rubbing hard surfaces together – Rubbing hard surfaces together – Low frequency sounds – Low frequency sounds

• • Vibration of swimbladder Vibration of swimbladder – Can give loud croaking – Can give loud croaking

• • Incidental to other activitiesIncidental to other activities

Chemical Signals Chemical Signals Chemical Signals Chemical Signals

• • Pheromones released into the Pheromones released into the water water – Reproductive cues – Reproductive cues – Recognition – Recognition • Schreckstoff = fear scents • Schreckstoff = fear scents – Predator avoidance – Predator avoidance – Produced in epidermal cells – Produced in epidermal cells

• • Pheromones released into the Pheromones released into the water water – Reproductive cues – Reproductive cues – Recognition – Recognition • Schreckstoff = fear scents • Schreckstoff = fear scents – Predator avoidance – Predator avoidance – Produced in epidermal cells – Produced in epidermal cells

Electrical SignalsElectrical SignalsElectrical SignalsElectrical Signals

• Muscle contractions give off a Muscle contractions give off a weak weak -Some fish have electric producing -Some fish have electric producing organs organs – Used to locate prey or – Used to locate prey or conspecificsconspecifics

• Muscle contractions give off a Muscle contractions give off a weak weak -Some fish have electric producing -Some fish have electric producing organs organs – Used to locate prey or – Used to locate prey or conspecificsconspecifics