Bony FishBony FishClass osteichthyes Class osteichthyes

VARIETY: WHY

Many body shapes:Many body shapes:

Streamlined shape reduces Streamlined shape reduces dragdrag

Hinged tail increases Hinged tail increases swimming efficiencyswimming efficiency

Scales:Scales:

•Thin and overlappingThin and overlapping

•Covered by layer of skin and Covered by layer of skin and mucusmucus

•Grow as the fish growsGrow as the fish grows

Coloration:Coloration:

•Chromatophores: color cellsChromatophores: color cells

•Irridophores: shiny cellsIrridophores: shiny cells

Muscle: Red vs. whiteMuscle: Red vs. white

•Myoglobin=stores oxygen in musclesMyoglobin=stores oxygen in muscles

•Red muscle=more myoglobin=more Red muscle=more myoglobin=more swimming!swimming!

•White muscle=less myoglobin=slow!White muscle=less myoglobin=slow!

Osmoregulation: blood is less Osmoregulation: blood is less salty than oceansalty than ocean

•Drink waterDrink water

•KidneysKidneys

•Gills (chloride cells) excrete saltGills (chloride cells) excrete salt

Digestive organs:Digestive organs:

•Pyloric ceca: digestive glandPyloric ceca: digestive gland

• Intestine length:Intestine length:– Long=plant materialLong=plant material– Short=“meat”Short=“meat”

Temperature regulationTemperature regulation

•PoikilothermsPoikilotherms (most) (most)

•PseudohomeothermsPseudohomeotherms (some): (some): temp kept slightly higher than temp kept slightly higher than water (muscles make heat water (muscles make heat energy)energy)

Gills are efficient

• Low oxygen content in water

• Many gill filaments to increase surface area

• Active fish have more gill surface area (up to 10 times the body surface area!)

• Extract up to 85-90% of oxygen in water

• You extract about 20%

Counter Current Flow in Gills

• Water and blood flow in opposite directions within the gill space

• Diffusion occurs: oxygen into blood and Carbon dioxide out of blood

Fish countercurrent flow: gills

Oxygen flow into blood: dots represent oxygen flowing into blood

Operculum: pump to increase efficiency

• Bony plate helps to pump water over the gills

• Removes need to SWIM to respire: allows hovering, etc. and different shapes evolved

• Some fish like tuna have an operculum that no longer pumps; water is forced over the gills by fast swimming (Ram Gills)

SwimSwim BladderBladder

• Allows fish to be Allows fish to be NEUTRALLY BUOYANTNEUTRALLY BUOYANT

• May be open to the pharynx and air May be open to the pharynx and air enters here (pneumatic duct); gulpers enters here (pneumatic duct); gulpers /surface fish may do this/surface fish may do this

• Has a gas gland/rete mirable to get gas Has a gas gland/rete mirable to get gas into the bladderinto the bladder

Rete Mirable

• Chemical reactions cause blood to release oxygen into the swim bladder:

• Lactate levels in the blood increase pH levels drop hemoglobin releases oxygen which then diffuses back into the incoming capillary until oxygen pressure is greater than that of the swim bladderoxygen enters SB

Dr Seuss’s Law:

• One fish two fish

• Red fish blue fish!!

Boyle’s Law: Up fish out gas/down fish/in gas

• Fish swims up/pressure decreases/gas expands/fish must let gas out!

• Fish swims down/pressure increases/gas contracts/fish must let gas in!

Swim bladder used to make Swim bladder used to make soundssounds

Grunt

CroakerCroaker

PufferPuffer

Crevalle JackCrevalle Jack

SENSES

• Smell: (nares/olfactory sacs)• Color vision (cone cells)• Touch/vibrations (neuromast cells:

hairlike cells that detect motion• Taste (cells on lips, mouth, barbels)• Hearing (otoliths or ear stones for

vibrations)• Balance: semicircular canals

Why Variety? What structures have led to such variety?

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