Marine FishesMarine Fishes

What is a fish??What is a fish??Classic definition:Classic definition:

-Any of numerous cold-blooded aquatic vertebrates of the-Any of numerous cold-blooded aquatic vertebrates of the

superclass Pisces, characteristically having fins, gills, and asuperclass Pisces, characteristically having fins, gills, and a

streamlined body and including specifically, and...streamlined body and including specifically, and...

-Any of the class Osteichthyes, having a bony skeleton, and...-Any of the class Osteichthyes, having a bony skeleton, and...

-Any of the class Chondrichthyes, having a cartilaginous-Any of the class Chondrichthyes, having a cartilaginous

skeleton and including the sharks, rays, and skates. skeleton and including the sharks, rays, and skates.

Although this is all accurate...we will find that fish areAlthough this is all accurate...we will find that fish are

considerably MORE!!considerably MORE!!

Fish similarities...Fish similarities...

• Vertebrate ( chordate)Vertebrate ( chordate)

• Gills Gills

• PoikilothermicPoikilothermic

• FinsFins

• ScalesScales

Drag Reduction Features in FishDrag Reduction Features in Fish

• ““Fusiform” body shapeFusiform” body shape• Reduction of body wave amplitudeReduction of body wave amplitude• Reduction of surface areaReduction of surface area• Boundary layer modificationsBoundary layer modifications

What is a fusiform body shape?What is a fusiform body shape?

• pointed leading edgepointed leading edge• maximum depth 1/3 body length back from headmaximum depth 1/3 body length back from head• posterior taperposterior taper• caudal fin interrupts ideal fusiform shapecaudal fin interrupts ideal fusiform shape

Ostracoderms

– Class Pteraspidomorphi (sp. diplorhina = “two nares”)

– they literally had two separate olfactory bulbs in the brain.

– those with a different shell, i.e. dermal armor

Placoderms - earliest gnathostomesPlacoderms - earliest gnathostomes(jawed vertebrates)(jawed vertebrates)

• True jaws = more food!True jaws = more food!• Paired fins = more food!Paired fins = more food!

Hagfish (Agnatha): jawless fishHagfish (Agnatha): jawless fish

LampreyLamprey

• Predatory/parasiticPredatory/parasitic• Rasping teethRasping teeth

Parasitism of Great Lakes fishes…Parasitism of Great Lakes fishes…

Cartilagenous Fishes(Sharks, Skates and Rays)

Distinguishing Elasmobranch TraitsDistinguishing Elasmobranch Traits

cartilaginous skeletonno swim bladderheterocercal tailplacoid denticles - scales and teethspiracles present with 5-7 gill slits (no operculum)urea retained for osmoregulationspiral valve in intestinemales have claspers, internal fertilizationoviparous, ovoviviparous, viviparousteeth in rows, are constantly replaced

Elasmobranch… plate or strap gill

Sharks exhibit extreme variability in size, shape and abilities.

Nearly 850 spp. of sharks, 350 exhibit typical Nearly 850 spp. of sharks, 350 exhibit typical body morphology.body morphology.

Variations on this theme are common.Variations on this theme are common.

Carchariniformes – basking sharks, filter feeder

Cetorhinus maximus Cetorhinus maximus

Great White, Great White, Carcharodon carchariasCarcharodon carcharias

Mako Great WhiteGreat WhiteIsurus oxyrinchusIsurus oxyrinchus

Lamniformes - mackerel,Lamniformes - mackerel, mako, white sharksmako, white sharks-carnivores-carnivores

Skates and rays Skates and rays spend most of their lives near (on) the spend most of their lives near (on) the

ocean floor eating molluscs, squid, and small fish.ocean floor eating molluscs, squid, and small fish.

Yellow stingray, Urolophus jamaicensis

Like sharks, skates and rays come inLike sharks, skates and rays come in

many shapes and sizes.many shapes and sizes.

Blue spotted ray, Blue spotted ray, Taeniura Taeniura lymmalymma

Skates (order Rajiformes)

•pelvic fin divided into two lobes  •tail relatively stocky, no spine 

Rays (order Myliobatiformes)

•each pelvic fin with one lobe  •tail relatively slender to whip-like spine

Spotted ratfish Spotted ratfish Hydrolagus collieiHydrolagus collieiFamily: chimaeridaeFamily: chimaeridae

• Identification: Broad, flat, duckbill shaped snout Identification: Broad, flat, duckbill shaped snout containing incisor shaped teeth. Prominent, venomous containing incisor shaped teeth. Prominent, venomous spine at leading edge of  dorsal fin. Tapering tail spine at leading edge of  dorsal fin. Tapering tail constitutes almost half overall length. Coloration  brown constitutes almost half overall length. Coloration  brown or grey with white spots. Skin smooth and scaleless. Can or grey with white spots. Skin smooth and scaleless. Can give off an iridescent, silvery sheen.  Fins grey or dark.give off an iridescent, silvery sheen.  Fins grey or dark.

• Size: up to 97cm in length.Size: up to 97cm in length.

Boneless Boneless vs.vs.BonyBony

Found in sharks and rays, and can vary greatly in external appearance. They do not increase in size as the fish grows, instead new scales are added. Placoid scales are often referred to as

denticles. Placoid scales consist of a flattened rectangular base plate which is embedded in the fish, and variously developed structures, such as spines, which project posteriorly on the surface. The spines give many species a rough texture.

Placoid scales

Placoid scales of the Broadnose Sevengill Shark.

Cycloid and Ctenoid Scales

Found in bony fishes (the Teleostei). Overlapping = flexibility, over cosmoid or ganoid scales.

Cycloid scales—smooth posterior margin, no ctenii. (Greek "cyclo“ or circle.)

Fish form and functionFish form and functionshow a high degreeshow a high degreeof variation.of variation.

Coloration is also veryColoration is also veryimportant in fish.important in fish.

Here a stonefish “disappears”Here a stonefish “disappears”amid the coral background.amid the coral background.

ChromatophoresChromatophores, specialized, specializedpigment cells within itspigment cells within itsskin provide protective skin provide protective coloration.coloration.

• • Disrupt the outline of the fish Disrupt the outline of the fish

• • Being dark on top, light on bottom Being dark on top, light on bottom – Look like substrate from above – Look like substrate from above – Look like water surface from below – Look like water surface from below

Warning coloration! May indicate poisonous Warning coloration! May indicate poisonous amimal.amimal.

Fish LocomotionFish Locomotion

Fish LocomotionFish 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

Skeletal Fish Muscle:Skeletal Fish Muscle:

•Essentially three types of fish muscle: red, white, pink.Essentially three types of fish muscle: red, white, pink.

•Red muscleRed muscle (oxidative): Highly vascularized, myoglobin (oxidative): Highly vascularized, myoglobin containing tissue used during containing tissue used during sustained swimmingsustained swimming. Small . Small diameter and high blood volume = rich Odiameter and high blood volume = rich O22 supply! supply!

Presence leads to strong flavor in some fishes (tuna). Presence leads to strong flavor in some fishes (tuna).

•White muscleWhite muscle (glycolytic): Little vascularization. Used (glycolytic): Little vascularization. Used during “sprint” swimming. Large diameter fibers. during “sprint” swimming. Large diameter fibers.

•Pink musclePink muscle: This one is sort of in between red and : This one is sort of in between red and white. Serves in sustained swimming, but not to the extentwhite. Serves in sustained swimming, but not to the extent that red muscle is used.

Swimming Styles Swimming Styles Body wavesBody 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 wavesPartial 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 beatsCaudal peduncle/fin beats Ostraciform (boxfish- Ostraciform (boxfish-like and puffer-like)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

Fish Feeding - functionFish Feeding - function

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

fishes, no cartilaginous fishes, no cartilaginous fishesfishes

• browsers - selective - browsers - selective - eat only the planteat only 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, Fish Feeding - function, cont.cont.

• CarnivoresCarnivores– zooplanktivoreszooplanktivores

• suction feedingsuction feeding

• ram feedingram feeding

– benthic invertebrate benthic invertebrate feedersfeeders

• graspersgraspers

• pickerspickers

• sorterssorters

• crusherscrushers

Fish Feeding - function, Fish Feeding - function, cont.cont.

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

• active pursuitactive pursuit

• stalkingstalking

• ambushingambushing

• luringluring

Fish feeding behaviorFish feeding behavior

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

Feeding behaviorFeeding behavior

• Fish show versatility in Fish show versatility in prey choice and ingestionprey choice and ingestion

• Behavior tightly linked to Behavior tightly linked to morphology morphology

(co-evolution)(co-evolution)

Similar to Darwin’s finches, different shaped Similar to Darwin’s finches, different shaped mouths permit specialization on many prey mouths permit specialization on many prey items.items.

Digestive Digestive SystemsSystems

CartilagenousCartilagenousvs.vs.

Teleost (bony)Teleost (bony)

Fish circulation is a Fish circulation is a closed systemclosed system. Heart . Heart pumps blood through a loop of arteries, veins, pumps blood through a loop of arteries, veins, and capillaries.and capillaries.

Gills: the best wayGills: the best wayto gain oxygen (Oto gain oxygen (O22))

from an environment from an environment where its concentrationwhere its concentrationis already very low.is already very low.

Counter-currentCounter-currentcirculationcirculation permits O permits O22

to diffuse from high toto diffuse from high tolow concentration, evenlow concentration, evenacross venous tissueacross venous tissueafter most Oafter most O22 has been has been

removed from the waterremoved from the waterby gills.by gills.

Salt BalanceSalt BalanceRevisitedRevisited

Rem:Rem:Freshwater fishFreshwater fish[salt] inside fish > [salt] inside fish > [salt] outside [salt] outside

Saltwater fishSaltwater fish[salt] inside < [salt] inside < [salt] outside fish[salt] outside fish

Structure of Lateralis Structure of Lateralis CanalsCanals

• Epidermal tunnelEpidermal tunnel

• Pores open from canal to Pores open from canal to skin surfaceskin surface

• NeuromastsNeuromasts distributed distributed within tunnelwithin tunnel

• Fluid in tunnel is Fluid in tunnel is moremore viscous than water; viscous than water; therefore, more resistant therefore, more resistant to flowto flow

Lateral line also aids in navigation in close quarters.Lateral line also aids in navigation in close quarters.

Damselfish, Chromis spp.

Predator avoidancePredator avoidance

Fish Migrations: food, spawningFish Migrations: food, spawning

Migration for some salmon is a one-way trip!Migration for some salmon is a one-way trip!

Freshwater eels, Freshwater eels, Anguilla rostrataAnguilla rostrata are at the extreme are at the extreme end of migratory patterns, taking an entire life to end of migratory patterns, taking an entire life to make the round trip. Adults spend 15 years in fresh make the round trip. Adults spend 15 years in fresh water before making the return trip to spawning water before making the return trip to spawning grounds.grounds.

Reproduction in FishesReproduction in Fishes

Reproductive traits and life-history patternsReproductive traits and life-history patterns

Mating systems:Mating systems:– Promiscuous - both sexes with multiple partners -

most (common)– Polygynous - males with multiple mates (cichlids)– Polyandry - females with multiple mates – few

(Anglerfish, males “parasitize” females, clownfish)

– Monogamy - mating pair remains together over time, long gestation of young (some cichlids, seahorses, pipefish)

Courtship/ritualistic displays are patterns of Courtship/ritualistic displays are patterns of behavior observed in many fish.behavior observed in many fish.

Some marine fish have specialized reproductive Some marine fish have specialized reproductive organs.organs.

Claspers in elasmobranchs: male reproductive organClaspers in elasmobranchs: male reproductive organ

Egg laying (ovipary) in sharks, is a common menthod Egg laying (ovipary) in sharks, is a common menthod of fish reproduction.of fish reproduction.

swell shark egg, Cephaloscyllium ventriosum