Reading Assignment: Chapter 23: Perciformes end

Notice: Projects Due: Wednesday 10 December end

Behavior & Communication: 1. Schooling 2. Feeding 3. Aggressive Behavior 4. Dominance Hierarchies 5. Resting Behavior end

1. Schooling - moving in close coordinated association 25% of fishes school –herring schools to 4.5 billion m density fish per m 3 1/7 th vol. of Lake Sakakawea –consider: Lake Sakakawea 30 billion m mi long; 185 ft max depth end

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 end

sergeant major end

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 end

Hydrodynamics of Schooling thrust streamlines turbulence end

Carangidae--bigeye jack school end

diagonal banded sweetlips end

Advantages of Schooling continued: increased efficiency in finding food increased reproductive success end

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 end

Scaridae--parrot-fishes end

cookie cutter shark end

cookie cutter shark end

goblin shark caught at depth of 960 m end

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 end

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 end

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

Aggressive Behavior continued: Aggressive encounters: –charges –nips –flare fins –lateral displays –submissive behaviors end

Aggressive Behavior continued: Factors affecting aggressive advantage: –size –prior residency –result of previous encounters Dominance Hierarchies –often established in interacting groups –Advantages/Disadvantages? end

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 end

Communication Pheromones--already covered 1. Visual Signals 2. Auditory Signals end

1. Visual Signals: Color -- important in visual comm. –pigments: carotenoids - reds, yellows (contribute to green) melanins - dark red, brown, black end

Color continued: –Structural colors: (reflected light) purines - reflective (colorless) –ex: guanine (iridiophores) cells containing guanine –iridescence: produced when light waves are reflected in parallel end

carotenoids clown fish end

Salvelinus fontinalis--brook trout carotenoids end

carotenoids diagonal banded sweetlips end

melanins end

Poeciliidae -- black mollymelanins end

Etheostoma nigrum - johnny dartermelanins end

guanine blue marlin end

guanine Hiodon alosoides -- goldeye end

guanine Dorosoma petenense -- threadfin shad end

guanine Sphyraenidae -- barracuda end

Example of coloration: Campostoma--stoneroller end

Example of coloration: end

Etheostoma exile--Iowa darter Example of coloration: end

Lepomis cyanellus -- green sunfish Example of coloration: end

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

acetylcholine Chromatophore pigment Return to normal color

Function of coloration thermoregulation - dark absorbs heat; light reflects heat intraspecific communication evasion of predators

squirrelfish red coloration Examples: red--first wavelength to be filtered

red coloration short distance advertisement northern redbelly dace

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

queen angelfish

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 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

photophoresdragonfish Light producing cells Most common in twilight-zone fishes m Self-liminescence--liciferin/luciferace chem. react Symbiotic luminescence--luminescent bacteria in gland-like structures

photophores lanternfish