I.I. Fishes - BiologyFishes - Biology

B.B. ColorationColoration• Pigments in Pigments in chromatophoreschromatophores

• Specialized cells in skinSpecialized cells in skin• Many fishes can change colors rapidly by expanding or Many fishes can change colors rapidly by expanding or

contracting pigment in chromatophorescontracting pigment in chromatophores• Structural colorsStructural colors – Produced by reflective crystals in – Produced by reflective crystals in

iridophoresiridophores (specialized chromatophores) (specialized chromatophores)• FunctionsFunctions1.1. Warning colorationWarning coloration

• Dangerous, poisonous, bad tastingDangerous, poisonous, bad tasting2.2. Cryptic colorationCryptic coloration

• Blend with environment – hide from predators, stalk Blend with environment – hide from predators, stalk preyprey

3.3. Disruptive colorationDisruptive coloration• Break up outline of individual fish – confuse predatorsBreak up outline of individual fish – confuse predators

4.4. CountershadingCountershading• Dark top, light bottomDark top, light bottom• Camouflage in open waterCamouflage in open water

Warning

Cryptic Countershading

Disruptive

I.I. Fishes - BiologyFishes - Biology

C.C. LocomotionLocomotion• Most fishes swim using rhythmic contractions Most fishes swim using rhythmic contractions

produced by bands of muscles – produced by bands of muscles – myomeresmyomeres• Myomeres connect to backbone for supportMyomeres connect to backbone for support• Swimming muscles make up large percentage of Swimming muscles make up large percentage of

body weight (up to 75% in tunas and active body weight (up to 75% in tunas and active swimmers)swimmers)

1.1. SharksSharks• Lack swim bladderLack swim bladder• Generate lift withGenerate lift with

1)1) Buoyant oily liverBuoyant oily liver2)2) Heterocercal tailHeterocercal tail3)3) Rudder-like pectoral finsRudder-like pectoral fins

2.2. Rays and skatesRays and skates• Generate lift with large pectoral finsGenerate lift with large pectoral fins• Narrow tail plays minor role in swimmingNarrow tail plays minor role in swimming

Fig. 8.12

I.I. Fishes - BiologyFishes - Biology

C.C. LocomotionLocomotion3.3. Bony fishesBony fishes

• Swim bladder provides buoyancySwim bladder provides buoyancy• Diversity in swimming stylesDiversity in swimming styles

1)1) Eel-likeEel-like – Undulation of body – Undulation of body• ExEx – Moray eel – Moray eel2)2) CaudalCaudal – Propulsion with tail and body – Propulsion with tail and body• ExEx – Tuna – Tuna3)3) PectoralPectoral – Tail contributes little – Tail contributes little• ExEx – Surgeonfish – Surgeonfish4)4) Dorsal/AnalDorsal/Anal – Tail used as rudder – Tail used as rudder• ExEx – Triggerfish – Triggerfish5)5) OtherOther• ExEx – Trunkfish – Trunkfish

Fig. 8.11

I.I. Fishes - BiologyFishes - Biology

D.D. FeedingFeeding1.1. Sharks and Cartilaginous FishesSharks and Cartilaginous Fishes

a.a. Bite pieces from large preyBite pieces from large prey• Tiger shark – Diverse stomach contentsTiger shark – Diverse stomach contents• Great white shark – Wound and waitGreat white shark – Wound and wait• Cookie cutter shark – Cut out chunksCookie cutter shark – Cut out chunks

b.b. Ingest smaller prey wholeIngest smaller prey whole• Nurse shark – Benthic invertebratesNurse shark – Benthic invertebrates

c.c. Filter plankton – Gill rakersFilter plankton – Gill rakers• Whale shark – WarmWhale shark – Warm• Basking shark – ColdBasking shark – Cold• Megamouth sharkMegamouth shark• Manta rayManta ray

I.I. Fishes - BiologyFishes - Biology

D.D. FeedingFeeding2.2. Bony FishesBony Fishes

a.a. Capture large prey wholeCapture large prey whole• BarracudaBarracuda• FrogfishesFrogfishes

b.b. Pickers - Ingest smaller prey wholePickers - Ingest smaller prey whole• Butterflyfish, SlipmouthButterflyfish, Slipmouth

c.c. GrazersGrazers• ParrotfishParrotfish• FilefishFilefish

d.d. Filter plankton – Gill rakersFilter plankton – Gill rakers• AnchoviesAnchovies• SardinesSardines• HerringsHerrings

Fig. 8.13

I.I. Fishes - BiologyFishes - Biology

E.E. Respiratory SystemRespiratory System1.1. Irrigation of GillsIrrigation of Gills

a.a. ChondrichthyesChondrichthyes• Force water over gills byForce water over gills by

• Swimming with mouth openSwimming with mouth open• Each gill lies in own Each gill lies in own gill chambergill chamber

• Open to outside through Open to outside through gill slitsgill slits• First pair of gill slits modified as First pair of gill slits modified as spiraclesspiracles• Open/Close mouth to ventilate gillsOpen/Close mouth to ventilate gills

b.b. OsteichthyesOsteichthyes• Gills housed in common gill chamberGills housed in common gill chamber

• Openings covered by Openings covered by operculumoperculum on each on each sideside

• Mouth opens/operculum closes & vice-versaMouth opens/operculum closes & vice-versa

Fig. 8.16

I.I. Fishes - BiologyFishes - Biology

E.E. Respiratory SystemRespiratory System2.2. Structure of GillsStructure of Gills

• Gills supported by cartilaginous or bony Gills supported by cartilaginous or bony gill archesgill arches• Each gill arch bears two rows of Each gill arch bears two rows of gill filamentsgill filaments• Each gill arch has projections called Each gill arch has projections called gill rakersgill rakers

• Filter out potentially damaging coarse particlesFilter out potentially damaging coarse particles• May be used for filter feeding in some speciesMay be used for filter feeding in some species

• Each gill filament contains rows of Each gill filament contains rows of lamellaelamellae• Contain dense networks of Contain dense networks of capillariescapillaries• Increase surface area for gas exchangeIncrease surface area for gas exchange• Greater numbers of lamellae in active swimmersGreater numbers of lamellae in active swimmers

3.3. Gas ExchangeGas Exchange• Occurs by diffusionOccurs by diffusion• Countercurrent exchangeCountercurrent exchange

• Increases efficiency of gas exchangeIncreases efficiency of gas exchange

Fig. 8.17