Reading Assignment: Chapter 23: Perciformes end. Notice: Projects Due: Wednesday 10 December end.

Reading Assignment:

Chapter 23: Perciformes

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Notice:

• Projects Due: Wednesday 10 December

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Behavior & Communication:

1. Schooling

2. Feeding

3. Aggressive Behavior

4. Dominance Hierarchies

5. Resting Behavior

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1. Schooling - moving in close

coordinated association • 25% of fishes school

– herring schools to 4.5 billion m3

• @ density 0.5-1 fish per m3

• 1/7 th vol. of Lake Sakakawea

– consider: Lake Sakakawea 30 billion m3

• 200 mi long; 185 ft max depth

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Advantages of Schooling:

• Reduced risk of predation– school may appear as large organism– collective alertness– predator confusion

• difficulty of selecting target (flock-shooting)

• movement camouflage

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sergeant majorend

Advantages of Schooling continued:

• Hydrodynamics--energetic efficiency in swimming– drafting– snout-cone effect– similar to V-formation in birds

• 25 birds could get a 70% increase in distance for a given energy expenditure

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Hydrodynamics of Schooling

thrust

streamlines

turbulence

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Carangidae--bigeye jack schoolend

diagonal banded sweetlips end

Advantages of Schooling continued:

• increased efficiency in finding food

• increased reproductive success

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2. Feeding Behavior• Generalists--wide variety of prey

– omnivores -- catfishes

• Specialists--specific prey– herbivores -- plant/algae eaters– planktivores– piscivores -- fish eaters– extreme specialists

• scale-eating cichlids• parrot fishes -- coral• cookie-cuter sharks

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Scaridae--parrot-fishesend

cookie cutter shark

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cookie cutter shark

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goblin shark

caught at depth of 960 m

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Feeding Behavior continued:

• Opportunists -- take advantage of abundant prey – even if outside normal mode of feeding– non-surface feeders may feed at surface during

mayfly hatch– trout feeding on insect hatches

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Foraging Factors:

• prey size versus mouth size• energetic efficiency--energy spent versus energy

gained– prey distance– ease of capture - speed; maneuverability– handling - spines; armor– ease of digestion - composition; scales; bone– energy/nutrient content

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3. Aggressive Behavior

• Territoriality - some defend territories, generally for a limited resource– mates– breeding sites– feeding territories– Ex. Tilapia in thermal gradient

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Aggressive Behavior continued:

• Aggressive encounters:– charges– nips– flare fins– lateral displays– submissive behaviors

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Aggressive Behavior continued:

• Factors affecting aggressive advantage:– size– prior residency– result of previous encounters

• Dominance Hierarchies– often established in interacting groups– Advantages/Disadvantages?

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4. Resting Behavior

• “sleeping” or inactive

• observed in many species

• day night dusk dawn

• schools become disorganized

• some change color

• some do not react to vision or touch

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Communication

Pheromones--already covered

1. Visual Signals

2. Auditory Signals

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1. Visual Signals:• Color -- important in visual comm.

– pigments: • carotenoids - reds, yellows (contribute to green)• melanins - dark red, brown, black

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Color continued:

– Structural colors: (reflected light)• purines - reflective (colorless)

– ex: guanine (iridiophores) cells containing guanine

– iridescence: produced when light waves are reflected in parallel

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carotenoids

clown fishend

Salvelinus fontinalis--brook trout

carotenoids

end

carotenoids

diagonal banded sweetlipsend

melanins

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Poeciliidae -- black mollymelanins

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Etheostoma nigrum - johnny dartermelanins

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guanineblue marlin

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guanine

Hiodon alosoides -- goldeye end

guanine

Dorosoma petenense -- threadfin shad

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guanine

Sphyraenidae -- barracudaend

Example of coloration:

Campostoma--stonerollerend

Example of coloration:

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Etheostoma exile--Iowa darter

Example of coloration:

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Lepomis cyanellus -- green sunfish

Example of coloration:

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Chromatophores -- pigment cells

• branched cells

• contain pigments or reflective crystals

• pigments can be concentrated in center or distributed in branches

• control: neuro-endocrine system

Chromatophore

pigment

Vision & Nerve control

Normal coloration

EX: experiments with flounders--role of vision

Pleuronectiformes

adrenaline

Chromatophore

pigment

Lighter color

acetyl

cholin

e

Chromatophore

pigment

Return to normal color

Function of coloration

• thermoregulation - dark absorbs heat; light reflects heat

• intraspecific communication

• evasion of predators

squirrelfishred coloration

Examples:

red--first wavelength to be filtered

red coloration

short distance advertisement

northern redbelly dace

countershading

countershading

poster colors--complex color patterns

(common in reef fish)

Function of Poster colors:• advertisement of territory ownership• contact between foragers• intraspecific communication of sex, status,

maturity (Labridae, Scaridae)• predator avoidance--cryptic on color

background• aposmatic coloration--advertisement of

danger (poison; spines)

poster colors

butterfly fish

poster colors

poster colors

queen angelfish

poster colors

poster colors lionfish--aposmatic coloration

disruptive coloration--patterns that disrupt outline

flicker fusion--patterned fish against patterned background

disruptive coloration

camouflage

disruptive coloration

camouflage

disruptive coloration

camouflage

disruptive coloration

camouflage

guitarfish

disruptive coloration

camouflage

leafy seadragon

eye concealment

eye concealment

eye concealment

eye enhancement

French angelfish

eye enhancement

moray eel

eyespots

lateral stripes

common in schooling spp

For orientation &

pred. confusion

lateral stripes

polychromatism

• different colors in different individuals– ex: midas cichlid

• gold morphs win comp. for food

• rarely common in wild (prob. due to pred.)

– ex: annual killifish• brightly colored morphs dominant--greater

reproductive success early

• dull forms live longer--rep. success later in season

special patterns

Ex: egg-shaped spots on male cichlids– mouth brooders– females take eggs into mouth after laying– attempts to pick up “dummy” eggs aids

fertilization

photophores dragonfish

Light producing cellsMost common in twilight-zone fishes 300-1000 m

Self-liminescence--liciferin/luciferace chem. react

Symbiotic luminescence--luminescent bacteria

in gland-like structures

photophores

lanternfish