Functional Functional Morphology: Morphology: Locomotion Locomotion

&& FeedingFeeding

Chapter 8Chapter 8(Helfman, Collette & Facey)(Helfman, Collette & Facey)

Fish Locomotion

• Primary forces involved in fish swimming:Primary forces involved in fish swimming:– ThrustThrust - force that propels forward - force that propels forward– DragDrag - friction produced from passing an object - friction produced from passing an object

through a mediumthrough a medium– GravityGravity – force from earth’s magnetic pull – force from earth’s magnetic pull

(partially counterbalanced by density of water)(partially counterbalanced by density of water)

– LiftLift - upward force that counteracts gravity - upward force that counteracts gravity

Swimming Styles...Thrust Generation

• Body waves – AnguilliformBody waves – Anguilliform

• Partial body waves – (Sub)Carangiform Partial body waves – (Sub)Carangiform

• Caudal peduncle/fin beats – OstraciformCaudal peduncle/fin beats – Ostraciform

• Medial fin waves - Amiiform Medial fin waves - Amiiform

• Pectoral fin beats -LabriformPectoral fin beats -Labriform

Swimming Styles Swimming Styles Body waves Body waves Anguilliform (eel-like)Anguilliform (eel-like)

Lateral curvature in spine and Lateral curvature in spine and musculature that moves in a musculature that moves in a posterior directionposterior direction

Start: lateral displacement Start: lateral displacement of head, and then passage of of head, and then passage of this displacement along the this displacement along the body axis to the tailbody axis to the tail

Result: backward-Result: backward-facing “wall” of body facing “wall” of body pushing against the pushing against the waterwater

Swimming Styles Swimming Styles Partial body waves Partial body waves (Sub) Carangiform, Thunniform (tuna-like)(Sub) Carangiform, Thunniform (tuna-like)

Body wave begins posterior to head and increases with Body wave begins posterior to head and increases with amplitude as it moves posteriorlyamplitude as it moves posteriorly

Reduced drag compared to full body wave swimmingReduced drag compared to full body wave swimming

Wave STARTS at the caudal peducle (deeply forked, Wave STARTS at the caudal peducle (deeply forked, lunate)lunate)

Swimming Styles Swimming Styles Caudal peduncle/fin beats Caudal peduncle/fin beats Ostraciform (boxfish-like and puffer-like)Ostraciform (boxfish-like and puffer-like)

Sculling action of caudal fin—like rowingSculling action of caudal fin—like rowing

No body wavesNo body waves - body remains rigid - useful for odd- - body remains rigid - useful for odd-shaped fishesshaped fishes

Swimming Styles Swimming Styles Medial fin wavesMedial fin wavesAmiiform - bowfin-likeAmiiform - bowfin-like

Body rigid, but medial fins generate posterior waves Body rigid, but medial fins generate posterior waves (forward) or anterior (reverse)(forward) or anterior (reverse)

Good for stalking or moving without disrupting body Good for stalking or moving without disrupting body musculature that serves as electric organ (knifefish)musculature that serves as electric organ (knifefish)

Also used for sculling - triggerfish & othersAlso used for sculling - triggerfish & others

Swimming StylesSwimming Styles

Pectoral fin beatsPectoral fin beats LabriformLabriform

wrasse-like wrasse-like

Similar to rowingSimilar to rowing laterally-positioned laterally-positioned

pectoral fins- often includes pectoral fins- often includes feathering as wellfeathering as well

Especially useful for fine maneuveringEspecially useful for fine maneuveringe.g. by deep-bodied fishese.g. by deep-bodied fishes

Drag Reduction Features in Fish• Fusiform body shapeFusiform body shape• Reduction of body wave amplitudeReduction of body wave amplitude• Reduction of fin surface area:Reduction of fin surface area:

– caudal fin (forked, lunate)caudal fin (forked, lunate)– paired and medial finspaired and medial fins

• Boundary layer modificationsBoundary layer modifications– mucousmucous– laminar jets of waterlaminar jets of water– microprojectionsmicroprojections

Fusiform body shape

• pointed leading edgepointed leading edge• maximum depth 1/3 body length back from maximum depth 1/3 body length back from

headhead• posterior taperposterior taper• ““propellor” (caudal fin) interrupts perfect propellor” (caudal fin) interrupts perfect

fusiform shapefusiform shape

Body wave modifications

• Minimize lateral movement of head to Minimize lateral movement of head to reduce drag - subcarangiformreduce drag - subcarangiform

• Increase amplitude as wave moves in Increase amplitude as wave moves in posterior directionposterior direction

• Ultimate expression involves no body Ultimate expression involves no body waves, but alternate contraction and transfer waves, but alternate contraction and transfer of body musculature energy to caudal of body musculature energy to caudal peduncle and caudal fin - thunniformpeduncle and caudal fin - thunniform

Fin surface area reduction

• Area of fins increases dragArea of fins increases drag• Permanent design modifications: forked caudal Permanent design modifications: forked caudal

fins, reduced length of medial finsfins, reduced length of medial fins• Adjustable design modifications: variable erection Adjustable design modifications: variable erection

of fins - allows for minimizing surface area when of fins - allows for minimizing surface area when fin is not needed for thrust or turning - ultimate fin is not needed for thrust or turning - ultimate expression: fairings in tunas (dorsal and pectoral expression: fairings in tunas (dorsal and pectoral fin pockets)fin pockets)

Boundary layer modification• Layer of water immediately adjacent to skin Layer of water immediately adjacent to skin

causes most of friction - boundary layercauses most of friction - boundary layer• thickness of boundary layer is proportional to thickness of boundary layer is proportional to

amount of frictionamount of friction• three approaches to reducing thickness of three approaches to reducing thickness of

boundary layer:boundary layer:– smoothing it - making it “slicker”smoothing it - making it “slicker”

– roughing it - giving it tiny disruptions (golfers roughing it - giving it tiny disruptions (golfers learned from sharks??)learned from sharks??)

– shortening it - reducing distance of contactshortening it - reducing distance of contact

Boundary Layer, continued

• Fluid jets - from gill chamber and out operculum Fluid jets - from gill chamber and out operculum or in micropockets behind and beneath scalesor in micropockets behind and beneath scales

• mucous - slime adds to “slipperiness”, can reduce mucous - slime adds to “slipperiness”, can reduce drag by up to 65%drag by up to 65%

• microprojections - disrupt boundary layer so it microprojections - disrupt boundary layer so it cannot grow:cannot grow:– cteniictenii– placoid tipsplacoid tips

Buoyancy Control in Fishes

• Dynamic lift: generated by propelling a hydrofoil Dynamic lift: generated by propelling a hydrofoil forward at an inclined angle of attackforward at an inclined angle of attack

• Static lift: generated by including low-density Static lift: generated by including low-density substances and reducing mass of high density substances and reducing mass of high density substances in body.substances in body.

Dynamic Lift

• Hydrofoils: fish use their fusiform body and some Hydrofoils: fish use their fusiform body and some use their pectoral fins as hydrofoilsuse their pectoral fins as hydrofoils

• Amount of lift is determined by: angle of attack and Amount of lift is determined by: angle of attack and speed of propulsionspeed of propulsion

• Ultimate expression of this is in pelagic rovers - Ultimate expression of this is in pelagic rovers - tunas, mackerel sharkstunas, mackerel sharks– head, pectoral fins and peduncle keels all used as head, pectoral fins and peduncle keels all used as

hydrofoilshydrofoils– swim constantlyswim constantly

Static Lift

• Reduction of high density substances:Reduction of high density substances:– cartilage less dense than bonecartilage less dense than bone– use design features in bone that increase strength use design features in bone that increase strength

while reducing mass of bonewhile reducing mass of bone

• Inclusion of low-density fluidsInclusion of low-density fluids– lipids - squalene in sharks (sp. grav. = 0.86)lipids - squalene in sharks (sp. grav. = 0.86)

• stored in liverstored in liver

– gases - in swim bladdergases - in swim bladder• only in bony fishesonly in bony fishes

Swim bladders

• Gas-filled appendix to the anterior digestive Gas-filled appendix to the anterior digestive system; dorsal to abdominal organssystem; dorsal to abdominal organs

• Two types of swim bladders:Two types of swim bladders:– physostomous - pneumatic duct connects swim physostomous - pneumatic duct connects swim

bladder to esophagousbladder to esophagous– physoclistous - no connection between swim physoclistous - no connection between swim

bladder and gutbladder and gut

Food Aquisition&

Processing

1. Structure1. Structure

2. Function (behavior, 2. Function (behavior, physiology)physiology)

3. Nutritional needs3. Nutritional needs

4. Digestive efficiency4. Digestive efficiency

Food captureFood capture

• Mouth and pharyngeal cavityMouth and pharyngeal cavity

– upper jawupper jaw

– teeth - jaw, mouth, pharyngealteeth - jaw, mouth, pharyngeal

– gill rakersgill rakers

More on teethMore on teeth

Food captureFood capture

• Mouth and pharyngeal cavityMouth and pharyngeal cavity

– upper jawupper jaw

– teeth - jaw, mouth, pharyngealteeth - jaw, mouth, pharyngeal

– gill rakersgill rakers

Food captureFood capture

• Mouth and pharyngeal cavityMouth and pharyngeal cavity

– upper jawupper jaw

– teeth - jaw, mouth, pharyngealteeth - jaw, mouth, pharyngeal

– gill rakersgill rakers

GIGI

• EsophagusEsophagus• StomachStomach

– large in carnivores, large in carnivores, small in small in herbivores/omnivoresherbivores/omnivores

• Pyloric caecaePyloric caecae• IntestineIntestine

– short in carnivores, short in carnivores, long in long in herbivores/omnivoresherbivores/omnivores

• Anus - separate from Anus - separate from urogenital poreurogenital pore

GI- auxiliary organsGI- auxiliary organs• LiverLiver– produces bile (lipolysis)produces bile (lipolysis)

– stores glycogenstores glycogen

– stores lipidsstores lipids

• PancreasPancreas– digestive enzymesdigestive enzymes

• proteases - protein breakdownproteases - protein breakdown

• amylases - starch breakdownamylases - starch breakdown

• chitinases - chitin breakdownchitinases - chitin breakdown

• lipases - lipid breakdownlipases - lipid breakdown

Fish Feeding - function

• HerbivoresHerbivores– < 5% of all bony fishes, < 5% of all bony fishes,

no cartilaginous fishesno cartilaginous fishes• browsers - selective - eat browsers - selective - eat

only the plantonly the plant• grazers - less selective - grazers - less selective -

include sedimentsinclude sediments

• DetritivoresDetritivores– 5 - 10% of all species5 - 10% of all species

– feed on decomposing feed on decomposing organic matterorganic matter

Fish Feeding - function, cont.

• CarnivoresCarnivores– zooplanktivoreszooplanktivores

• suction feedingsuction feeding

• ram feedingram feeding

– benthic invertebrate benthic invertebrate feedersfeeders

• graspersgraspers

• pickerspickers

• sorterssorters

• crusherscrushers

Fish Feeding - function, cont.

• Carnivores, Carnivores, cont.cont.– fish feedersfish feeders

• active pursuitactive pursuit

• stalkingstalking

• ambushingambushing

• luringluring

Fish feeding behavior

• Fish feeding behavior integrates Fish feeding behavior integrates morphology with perception to obtain morphology with perception to obtain food:food:– SearchSearch– --> Detection--> Detection– --> Pursuit--> Pursuit– --> Capture--> Capture– --> Ingestion--> Ingestion

Feeding behavior

• Fish show versatility in Fish show versatility in prey choice and prey choice and ingestioningestion

• Behavior tightly linked Behavior tightly linked to morphology to morphology

(co-evolution)(co-evolution)

Fish feeding behavior

• Behavior tends to be optimizing when Behavior tends to be optimizing when choices are availablechoices are available– optimal = maximize benefit:cost ratiooptimal = maximize benefit:cost ratio– basically...more for less!basically...more for less!– i.e., select the prey that yields the greatest i.e., select the prey that yields the greatest

energetic or nutrient “return” on the energy energetic or nutrient “return” on the energy invested in search, pursuit, capture, and invested in search, pursuit, capture, and ingestioningestion

Fish digestive physiology

• After ingestion of food, gut is responsible for:After ingestion of food, gut is responsible for:– Digestion (breaking down food into small, Digestion (breaking down food into small,

simple molecules)simple molecules)• involves use of acids, enzymesinvolves use of acids, enzymes

– Absorption - taking molecules into bloodAbsorption - taking molecules into blood• diffusion into mucosal cellsdiffusion into mucosal cells

• phagocytosis/pinocytosis by mucosal cellsphagocytosis/pinocytosis by mucosal cells

• active transport via carrier moleculesactive transport via carrier molecules

Fish digestive physiology

• Digestion is accomplished inDigestion is accomplished in– StomachStomach

• low pH - HCl, other acids (2.0 for some tilapia!)low pH - HCl, other acids (2.0 for some tilapia!)

• proteolytic enzymes (mostly pepsin)proteolytic enzymes (mostly pepsin)

Fish digestive physiology

• Digestion is accomplished inDigestion is accomplished in– StomachStomach– IntestineIntestine

• alkaline pH (7.0 - 9.0)alkaline pH (7.0 - 9.0)

• proteolytic enzymes - from pancreas & intestineproteolytic enzymes - from pancreas & intestine

• amylases (carbohydrate digestion) - from amylases (carbohydrate digestion) - from pancreas & intestinepancreas & intestine

• lipases (lipid digestion) - from pancreas & liver lipases (lipid digestion) - from pancreas & liver (gall bladder, bile duct)(gall bladder, bile duct)

Fish digestive physiology

• Absorption is accomplished inAbsorption is accomplished in– IntestineIntestine

• diffusion into mucosal cellsdiffusion into mucosal cells

• phagocytosis/pinocytosis by mucosal cellsphagocytosis/pinocytosis by mucosal cells

• active transport via carrier moleculesactive transport via carrier molecules

Fish Nutritional Needs

• High protein diet:High protein diet:– carnivores - 40 - 55% protein neededcarnivores - 40 - 55% protein needed– omnivores - 28 - 35% protein neededomnivores - 28 - 35% protein needed– (birds & mammals - 12 - 25% protein (birds & mammals - 12 - 25% protein

needed)needed)– 10 essential amino acids (PVT. TIM HALL)10 essential amino acids (PVT. TIM HALL)

Fish Nutritional Needs

• High protein dietHigh protein diet• Why so high?Why so high?

– proteins needed for growth of new tissueproteins needed for growth of new tissue– proteins moderately energy-dense (don’t proteins moderately energy-dense (don’t

need dense source - ectotherms, low gravity)need dense source - ectotherms, low gravity)

– few side-effects - ease of NHfew side-effects - ease of NH44++ excretion excretion

Nutritional efficiency in fishes

• Fish more efficient than other Fish more efficient than other vertebrates:vertebrates:– conversion factor = kg feed required to conversion factor = kg feed required to

produce 1 kg growth in fish fleshproduce 1 kg growth in fish flesh• fishes: 1.7 - 5.0fishes: 1.7 - 5.0

• birds & mammals: 5.0 - 15.0birds & mammals: 5.0 - 15.0

Nutritional efficiency in fishes

• Fish more efficient than other Fish more efficient than other vertebratesvertebrates

• Why?Why?– ectothermy vs. endothermyectothermy vs. endothermy– energy/matter required to counterbalance energy/matter required to counterbalance

gravitygravity– bias of a high-protein dietbias of a high-protein diet

Nutritional efficiency

• Maintenance ration (MR) = the amount of food Maintenance ration (MR) = the amount of food needed to remain alive, with no growth or needed to remain alive, with no growth or reproduction (% body wt./day)reproduction (% body wt./day)

• MR is temperature-dependentMR is temperature-dependent– MR increases as temperature increasesMR increases as temperature increases

• MR is size-dependantMR is size-dependant– MR decreases as size increasesMR decreases as size increases

Temperature & Size effects - red hind (Serranidae)Temp (C) Fish mass

(g) MR (% body mass/day)

Maint. diet (g)

19 250 1.7 4.25

600 1.3 7.8

28 250 5.8 14.5

600 3.0 18.0