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7/31/2019 Fish Classification, Structure
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Vertebrates (subphylum vertebrata)
Possess a backbone (aka vertebral column,spine)
Vertebrae=Dorsal row of hollow skeletalelements (usually bone)
Nerve cord=spinal cord, protected by
vertebrae, (part of nervous system), ends inbrain
Bilateral symmetry, endoskeleton
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Fish Form & Function
Goals for this lab Learn about fish: Topics
Skin/scales
Coloration
Locomotion
Fins
Muscles
Discuss 3 classes of fish
Dissect different fish- up to 3 differentforms
Write paper comparing different fishforms
Due next Monday/Tuesday
Details to follow
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Global Habitats
58.2%
41.2%
39.9%
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Fish importance
Appeared > 500 mya
Comprise half of vertebrate species
Feed on all types of marine organisms
some organisms previously discussed use fish as theirhome (bacteria to crustaceans)
Some animals eat fish
Most economically important marine organism
Vital source of protein to millions of humans
Ground up for chicken feed, fertilizer, leather, glue,vitamins obtained from them
Some kept as pets
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Fish Morphology
Skin
Color
Bioluminescence
Swimming Locomotion
Fins
Muscles
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Skin
Organ of the body
Consists of connective tissue
Muscles pull against skin tissue & skeleton
Key component of the muscle-tendon-tail fin system
Layers
Epidermis
Typically 250 m thick 10-30 cell layersRange 20 m3 mm
Dermis
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Fish Skin
Function:
Hold fish together
Serves as barrier against abrasive agents
Osmoregulation (what does this mean?)
Permeable respiratory function
Biomechanical properties in sharks
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Fish Skin
Mucous formed in epidermis cells
Protect against infection
Constantly shed to remove bacteria and fungus
Ex. Clingfish lack scales, protect their bodies by
a thick layer of mucous
Bone is also skin derivative
scales, most important
Derivatives:
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Fish ScalesFirst appear as dermal bone
Found in fossil of Cambrian period (570 mya)
Layered bone, solid armor-constrained movement
Evolved smaller and reduced into scales
5 types of scales (examples with images to follow)
Placoid
Cosmoid
Ganoid
Cycloid
Ctenoid
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Fish Scales: Placoid
Found in elasmobranchs (sharks& rays)
teeth like, same composition
As fish grows, do not increase in
size, instead new scales are added
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Fish Scales: Cosmoid
In the Sarcopterygii (fish with fleshylobe fins), primitive fish
Less evolved than Elasmobranchs
and Actinopterygii (fish with rayed fins)
Scales found in fossil record but not
in any living fish,
Except in simplified version
of coelocanth and lungfish
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Fish Scales: Ganoid
In primitive Actinopterygii
Found in reedfish, polypterus, gar,
bowfin, and sturgeons
Were thick heavy scales when first
appeared
Rhomboid-shaped
Developed into teleost scales
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Fish Scales: Teleost scales
Ctenoid scales
Cycloid scales
Two types:
Ctenoid-higher fish
Cycloid-soft-rayed, anchovies, sardine
Mineralized surface layer & inner
collagenous layer
Scales surrounded by dermis, in dermal
pockets
Grow from top, bottom, and insides; overlaplower part
Scales grow with fish
Characterized by concentric ridges (growth
increments)
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Coloration
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Coloration
Fish display a multitude of patterns involving
2 or more colors,
in many tints and shades,arranged in spots, stripes, patches, and blotches
3 Types of coloration predominant in oceans
Silverpelagic, upper zoneReddeeper zone (~ 500 m)
Black or violetdeep sea
Countershaded near shore and colorful in coral reefs
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Coloration
Chromatophores
Colored cells from which light is reflected off
Located in the skin (dermis), eyes
Various colors/hues-combination of different chromatophores
Functional Roles of Colors in Fishes-examples of each to follow
Social Roles
Advertisement
Mimicry
Hiding
Protection from sun (especially larvae)
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Coloration: Social roles
Cleaner Fish:
distinctive markingsrecognized by larger fish
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Coloration:Advertisement:
Bright, bold and showy males indicate:
Reproductive availability, either
permanently or seasonally, e.g. cichlids,
wrasses, minnows, sunfishUnpalatable or venomous, e.g. lionfishes
MimicryDisguise:
Disguises: look like something in habitat,
e.g. leaffish, sargasso fish
Mimicry: mimic distasteful species
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Coloration: ConcealmentGeneral color resemblance
resemble backgroundVariable color resemblancechange
with background, e.g. flatfish
Obliterative shading
countershading, dark above, light
below (invisible fish)
Disruptive colorationdisruptive
contours that breakup outline; bold
stripes, bars, false eye spots
Coincident disruptive coloration
joining together of unrelated parts of
the body to reduce recognition; e.g. sea
dragon
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Coloration
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Bioluminescence
Most luminous fish found 300-1000 m depths, few shallow
3 Types of light producing methods:
Self-luminous (on/off)
Symbiotic bacteria nurtured in special glands
Acquire from other bioluminescent organisms- diet contains
light-emitting compounds
Function:
Concealment by counter-illumination - ventral placementmatches background from above, against attack from below
Dorsal photophores safeguard against predators from above
Advertisement for courting, maintaining territory, to startle and
confuse predators, and feeding
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Fish LocomotionMeans of Locomotion:
Simplest form: Passive drifting of larval fish
Many can:
Burrow
Walk, hop, or crawl
Glide
Fly
Most can:
Swim in a variety of ways
i
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FinsTypes of fins:
Paired fins: pectoral and pelvic
Median fins:dorsal, caudal, anal, & adipose
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Fins
Main functions:
Swimmingincrease surface area w/o increasing mass
Stabilizersyaw, stability-dorsal and anal fins
- brake, pitch, roll, reverse -pectoral/pelvic
thrust with caudal fin
Modifications in fins:
Defensespines, enlarge fish
Locomotionmodified for crawling, flying, gliding
Huntinglures, sensory organs
Respiratory organlungfish, supply oxygen to eggs
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FinsSoft rays vs. Spines
Soft rays:
Usually soft and not pointed
Segmented
Usually branched
Bilateral, w/left and right halves
Spines:
Usually hard and pointed
Unsegmented
Unbranched
Solid
Fi h M l
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Fish Muscles
Muscles provide power for swimming
Myomers=bands of muscle, run along sides of body, attached to
backbone
Constitute up to 80% of the fish itself
Much hardly used except during emergenciesDont have to contend with same effect of gravity
Fish muscle arrangement not suitable on land
Cow: 30% muscle/wt
Tuna: 60% muscle/wt
Contraction causes oscillation of body and tail
Body bends as one side contracts b/c of an incompressible
notochord or vertebral column
Caused by bands of muscle = myomeres
Fi h M l
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Fish MusclesMajor fibers (see handout):
Red, pink, and white
Pinkintermediate between red
and white
Muscle types do not intermingle
Different motor systems used for
different swimming conditions
Redcruising
Whiteshort duration, burstswimming
Pinksustained swimming,
used after red and before white
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Fish-Body shapes-see textbook for images
(Figure 8.9)
Fusiform-spindle shaped, e.g. tuna
Compressiform-laterally compressed,angelfish, butterfly fish
Anguilliform-eel-like
Filiform-even smaller anguilliform, e.g. snipeeel
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Body shapes continued
Depressiform-flatfish,rays, flounder
Taeniform-gunnel
Sagittiform-e.g. pike
Globiform-e.g.lumpsucker
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Fish Locomotion
Swimming classified into 2 generic categories:
Periodic (or steady or sustained)- e.g. running marathons,
for covering large distance at constant speed
Transient (or unsteady)e.g. like running sprints, used
for catching prey or avoiding predators
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Undulate
the body:
eels,
elongate
fish
Flex caudalportion, fast
swimmers
Isolate and
move only
fin(s)
Anguilliform
Carangiform
Subcarangiform
Ostraciform-rigid
body, caudal mai
propulsion
Thunniform-rigid
body, caudal main
propulsion
Labriform -pectoral oscillateDiodontiform - pectoral
Rajiform - pectoral
Amiiform -dorsalBalistiformanal+dorsal
(Wavelike) (fanlike)
Gymnotiform -anal
Tetraodontiformanal+dorsal
pectoral
anal
dorsal
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Tuna: Ultimate Living Swimming MachineSwim continuouslyfeeding, courtship, rest, reproduction
T Ul i Li i S i i M hi
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Tuna: Ultimate Living Swimming Machine
hydrodynamic adaptationsBig size-high performance engine
Streamlining-spindle shaped & rigid body
Small structures at various parts of the body to improve swimming
efficiency and reduce drag, e.g.
Eyes flush with bodydont protrude
Adipose eyelid - smooth, reduce drag
Depression grooves for dorsal, pelvic, & pectoral fins at high speed
Keeled peduncle - cutting through water
Finlets for cross-flow - delayed separation
T Ulti t Li i S i i M hi
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Tuna: Ultimate Living Swimming Machine
Must swim to survive:
No gas bladder, rigid body, ram ventilation
High blood volume, large heart, maintain warm core
(25oC)
School to utilize vortices generated by other fish (~like
race car driver who slipstreams and then slingshots pastleading car)
Adopt swim-glide for energy savings (like birds)
High narrow tailspropulsion with least effort, used todesign efficient propulsion systems for ships
Slipstream: The area of reduced
pressure or forward suction
produced by and immediately
behind a fast-moving object as it
moves through air or water.
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Fish-mouth types (some)
Large mouth with teeth (e.g. barracuda)
Long snout/small mouth (e.g. butterfly fish)
Protrusible mouth (e.g. slipmouth)
Large mouth (e.g. herrings)
Beak-like mouth (e.g. parrotfish)
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Fish
Three Classes:
Agnatha
Chondrithyes
Osteicthyes
Cl A h
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Class Agnatha
Jawless fishes
Ex. Hagfish, lampreys
No paired fins
Gill holes, no slits or operculum
Large sucking mouth with teeth
Scavengers
As a defense mechanism, secrete slime then tie itself in
knots to escape predators
Also tie in knots for pulling food off carcasses, and
cleaning slime from body
Class Agnatha
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Class Agnatha
Hagfishs
mouth
http://www.soest.hawaii.edu/oceanography/faculty/csmith/index.html
Cl Ch d i th
http://www.soest.hawaii.edu/oceanography/faculty/csmith/index.htmlhttp://www.soest.hawaii.edu/oceanography/faculty/csmith/index.html7/31/2019 Fish Classification, Structure
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Class ChondricthyesSharks and rays
Skeleton = cartilage, not bone
Paired fins-efficient
swimming
Gill slits exposed,
no operculum
Large oil-filled liver
Heterocercal tail (upperlonger than lower lobe)
Placoid scales-skin like
sandpaper
Class Osteichthyes
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Class Osteichthyes
Bony fish
Largest group of living vertebrates
Bones for skeletons
Gill covering (operculum)
Swim bladder (balloon-like)
Homocercal tails (even)
Cycloid & Ctenoid scales