Fish - University of San Diego Home Pages by dffhrtcv3

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									 Vertebrates (subphylum vertebrata)
• Possess a backbone (aka vertebral column,
  spine)
• Vertebrae=Dorsal row of hollow skeletal
  elements (usually bone)
• Nerve cord=spinal cord, protected by
  vertebrae, (part of nervous system), ends in
  brain
• Bilateral symmetry, endoskeleton
             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 different
  forms
• Write paper comparing different fish
  forms
    – Due next Monday/Tuesday
    – Details to follow
Global Habitats



                  41.2%




                   58.2%
                           39.9%
                 Fish importance
•   Appeared > 500 mya
•   Comprise half of vertebrate species
•   Feed on all types of marine organisms
•   some organisms previously discussed use fish as their
    home (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
       Fish Morphology
Skin
  Color
  Bioluminescence
Swimming Locomotion
  Fins
  Muscles
                     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 layers
          Range 20 m – 3 mm
      Dermis
             Fish Skin

Function:
   Hold fish together
   Serves as barrier against abrasive agents
   Osmoregulation (what does this mean?)
   Permeable  respiratory function
   Biomechanical properties in sharks
                      Fish Skin
Derivatives:
    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
Fish Scales
 First 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
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
  Fish Scales: Cosmoid
  In the Sarcopterygii (fish with fleshy
lobe 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
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
 Fish Scales: Teleost scales
  Two types:
     Ctenoid-higher fish
     Cycloid-soft-rayed, anchovies, sardine
  Mineralized surface layer & inner             Ctenoid scales
collagenous layer
  Scales surrounded by dermis, in dermal
pockets
  Grow from top, bottom, and insides; overlap
lower part
 Scales grow with fish
                                                   Cycloid scales
  Characterized by concentric ridges (growth
increments)
Coloration
                      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
     Silver – pelagic, upper zone
     Red – deeper zone (~ 500 m)
     Black or violet – deep sea
Countershaded near shore and colorful in coral reefs
                         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)
Coloration: Social roles
  Cleaner Fish:
  distinctive markings
  recognized by larger fish
Coloration:
Advertisement:
Bright, bold and showy males indicate:
Reproductive availability, either
permanently or seasonally, e.g. cichlids,
wrasses, minnows, sunfish
Unpalatable or venomous, e.g. lionfishes



Mimicry – Disguise:
Disguises: look like something in habitat,
e.g. leaffish, sargasso fish
Mimicry: mimic distasteful species
Coloration: Concealment
General color resemblance –
resemble background
Variable color resemblance – change
with background, e.g. flatfish
Obliterative shading –
countershading, dark above, light
below (invisible fish)
Disruptive coloration – disruptive
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
                   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 placement
 matches 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
                  Fish Locomotion
Means of Locomotion:
  Simplest form: Passive drifting of larval fish
   Some can:
          Burrow
          Walk, hop, or crawl
          Glide
          Fly
  Most can:
          Swim in a variety of ways
Types of fins:
                             Fins
      Paired fins: pectoral and pelvic
      Median fins: dorsal, caudal, anal, & adipose
                               Fins
Main functions:
     Swimming – increase surface area w/o increasing mass


     Stabilizers – yaw, stability-dorsal and anal fins
                  - brake, pitch, roll, reverse -pectoral/pelvic
                  thrust with caudal fin
     Modifications in fins:
         Defense – spines, enlarge fish
         Locomotion – modified for crawling, flying, gliding
         Hunting – lures, sensory organs
         Respiratory organ – lungfish, supply oxygen to eggs
                               Fins
Soft rays vs. Spines




 Soft rays:                              Spines:
    Usually soft and not pointed            Usually hard and pointed
    Segmented                               Unsegmented
    Usually branched                        Unbranched
    Bilateral, w/left and right halves      Solid
                    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 emergencies
    Don’t 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
                         Fish Muscles
Major fibers (see handout):
  Red, pink, and white
  Pink intermediate between red
and white
  Muscle types do not intermingle
   Different motor systems used for
different swimming conditions
      Red – cruising
     White – short duration, burst
   swimming
     Pink – sustained swimming,
   used after red and before white
               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
                pectoral
Isolate and                       Rajiform - pectoral
move only                                                Diodontiform - pectoral Labriform -pectoral oscillate




                           anal
   fin(s)
                                  Gymnotiform -anal

                dorsal
                                                                                 Tetraodontiform – anal+dorsal
                                                        Balistiform – anal+dorsal
                                   Amiiform -dorsal
                                                                                                  Ostraciform-rigid
Flex caudal                                                                                       body, caudal main
                                                                                                  propulsion
portion, fast
swimmers                                                                                  Thunniform-rigid
                                                                                          body, caudal main
                                                                                          propulsion
                                                                 Carangiform


                                                Subcarangiform
 Undulate
 the body:                 Anguilliform
    eels,
  elongate
    fish                                       (Wavelike)                                         (fanlike)
http://www.oceanfootage.com/stockfootage/Titan_Tr
igger_Fish//?DVfSESSCKIE=7305db92882366fd26
             c463edc209393f8e25bdc9
    Tuna: Ultimate Living Swimming Machine
Swim continuously – feeding, courtship, rest, reproduction
            Tuna: Ultimate Living Swimming Machine
                   hydrodynamic adaptations
  Big 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 body – don’t 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
              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 past
leading car)                                              Slipstream: The area of reduced
                                                            pressure or forward suction
                                                                      produced by and immediately
  Adopt swim-glide for energy savings (like birds)                   behind a fast-moving object as it
                                                                       moves through air or water.

 High narrow tails – propulsion with least effort, used to
design efficient propulsion systems for ships
Fish-mouth types (some)
  • Large mouth with teeth (e.g. barracuda)

  • Long snout/small mouth (e.g. butterfly fish)


  • Protrusible mouth (e.g. slipmouth)


  • Beak-like mouth (e.g. parrotfish)


  • Large mouth (e.g. herrings)
    Fish

Three Classes:
  Agnatha
Chondrithyes
 Osteicthyes
                        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

                                                                     Hagfish’s
                                                                     mouth




http://www.soest.hawaii.edu/oceanography/faculty/csmith/index.html
                Class Chondricthyes
  Sharks and rays
 Skeleton = cartilage, not bone
  Paired fins-efficient
swimming
  Gill slits exposed,
       no operculum
  Large oil-filled liver
  Heterocercal tail (upper
longer than lower lobe)
  Placoid scales-skin like
sandpaper
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
                Dissection Worksheet
•Working in groups of 2 or 3 people,
    • dissect 1 fish following the worksheet and writing the answers to
    the questions in your notebook as you go.
• Need to draw 3 external illustrations in your notebooks
    • 1 of the fish you are dissecting, before you dissect it
    • 2 others that have specialized mouths and caudal fins
        • label the type of mouth and caudal fin each has
    • Label the following structures on each illustration:
        • gill cover, pectoral fins, pelvic fins, dorsal fin,
        • anal fin, adipose fin (if present), lateral line
        • give the head length, total length, and the fork length (of the
        dissected one ONLY, see handout)
        • look at a scale under a microscope and draw it.
 Dissection Worksheet continued
• Cut through body cavity
   – Find the following
      •   Heart
      •   Liver
      •   Stomach/intestines
      •   Swim bladder (if applicable)
      •   Spine
• Cut cross section, 2/3 down the body
   – Red muscle
   – White muscle
            Scales- use slides
• Draw
  –   Placoid
  –   Ganoid
  –   Cycloid
  –   Ctenoid

								
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