Bony Fish by xiaoyounan


									Bony Fish
Class Osteichthyes

    Includes all bony fishes
    Cold-blooded vertebrates
    Largest class of all vertebrates
    Accounts for 96% of all fish species.
    Freshwater and Marine
Distinguishing Features

    Skeleton of bone
    Scales
    Paired fins
    Single pair of gill openings
    Jaws
    Paired nostrils
Body Shape

  Primarily Fusiform shape
  Deviate in 3 ways
    Laterally compressed: common for fish who
     live in dense cover or coral reefs.
       Example: Butterflyfish
    Depressed: common in bottom dwelling fish
       Example: Sea Moth
    Elongated: common in open ocean fish and
     eels. Example: Barracuda
Laterally Compressed

  Butterfly fish
Depressed body shape

  Sea Moth

  Barracuda

  Most fish species have pigmentation
   called chromatophores.
  Chromatophores can contract and
   expand to change colors.
  Iridescent- Reflective scales
  Cave dwelling fish lack pigmentation.

  Fish using chromatophores to match

  Fish reflects light and matches
Purpose of Coloration
 Camouflage
   Countershading
   Disruptive coloration- breaks up animals shape
   Change color to match surroundings
 Advertisement to other fishes
   Mate attraction and recognition
   Territorial behavior
   Warning signs
Disruptive Coloration

  Moorish Idols

  Some species produce light through a
   chemical reaction process.
  Used to attract mates, confuse or deter
   predators, or attract prey
  Light production occurs in
    Photophores- light producing cells
    Light-producing bacteria- live in or on the
     fish in a symbiotic relationship
Attract Prey

  Angler Fish
 Two kinds of fins-
   Paired fins- Pectoral and Pelvic
   Median fins- Dorsal, Caudal, and anal
 Most fins are supported by rays (soft or rigid)
 Some species have spiny rays associated
  with venom glands.
   Example: Stonefish, Lionfish, Scorpionfish
Venomous Spines

  Lionfish, warning colors
Head Structure

  Mouth- located on anterior end
  Nostrils- used for smell, no connection to
  Gills- Single pair of openings, covered by
   a flexible plate called Operculum.
  Teeth- fused to the jaw bone
  Eyes- size and position vary by habitat
   and behavior. Deeper = bigger eyes

  Scales are thin and flexible
  Develop from bone tissue
  Scales overlap from head to toe to
   reduce drag.
  Covered by a thin layer of tissue as well
   as mucus.
  Some bony fishes only have scales on
   portion of body, or none at all
4 Types of Scales

  Cosmoid (primitive)

  Ganoid

  Cycloid

  Ctenoid
Purpose of Mucus

  Helps to protect fish from infection
  Covers body to conceal scent from
    Example: Parrotfish enclose their bodies in
     a mucus bubble at night so predators cannot
     detect them
  Some juvenile fish feed on the mucus of
Parrotfish enclosed in

  Buoyancy provided by gas-filled swim
  Gas volume changes as the fish changes
Swim Bladder

  Average lifespan of fish is 12-20 years.
  Larger species typically live longer than
   smaller species.
  Infections and parasites are common
   causes of death in fish.
3 Types of fish Movement

  1) Most fish swim with a rhythmic side to side
   motion of the body or caudal fin
  2) Elongated fish like eels swim using a
   serpentine motion. They undulate their body in
   lateral waves that travel from head to tail.
  3) Other fish, like tuna, have shorter bodies
   and swim by moving only powerful and rigid
   caudal tail. (fastest)
 Most fish reproduce externally by spawning
 Females lay eggs and males release sperm
 Eggs will
     1. Drift in water column
     2. sink and remain on bottom
     3. Eggs may be sticky and attach to plants etc.
     4. Some fish brood eggs in mouth
     5. Some bury eggs
  Some fish have internal fertilization and are
     Seahorse: Females deposit eggs in a pouch on the male’s
     The male then releases sperm and the eggs develop inside
      the male.
     The male then gives birth
  Some fish are hermaphrodites.
     Sequential - Born one sex but change at some point during life
      due to social hierarchy/behavior
     Synchronous- Have both sperm and egg producing organs at
      the same time.

  The number of offspring is inversely
   related to the chances of the eggs
   reaching maturity.
  The larger number of eggs laid means
   there is a lower chance of surviving.
    The Common Mola lays 28 million eggs in a
     single season.
    The Atlantic Tarpon releases over 100
     million every time it spawns.
Breeding Behavior

  Various factors may influence breeding
      1. Change in duration of sunlight
      2. Temperature change of the water
      3. Presence of the opposite sex
      4. Change in currents, tide, or stages of the
Breeding Cycles
 Reproduction is generally cyclic in bony fish.
 Some spawn many times a year, while
  others spawn only once a lifetime and then
  die soon after. Ex: Pacific Salmon
 Anadromous- Fish that spend most of their
  time in the sea, but breed in rivers.
 Catadromous- FW fish that migrate to the
  sea to breed.

  Hearing- No external opening; inner ear for
   equilibrium, detecting acceleration, and
  Eyesight- Well developed for some species.
  Taste- taste buds inside mouth, responsible for
   accepting or rejecting prey
  Smell- well developed
  Lateral Line- Vibrations
Human Interaction

  1. Commercial Fishing
  2. Recreational fishing
  3. Habitat destruction- building dams,
   stream diversion, destroy coastal
  4. Pollution
  5. Introduced species
  6. Aquarium Collection

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