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Chapt 10 Bony Fishes

      Ichthyology
   “the study of fish”
Phylum Chordata
• Class Actinopterygii
   – “modern bony fish”
   – 25,000 species or ½ of all
     vertebrate species
   – So diverse no one
     characteristic can
     differentiate them from
     sharks, skates, and rays
     (cartilaginous fish)
   – Taxonomy of fishes are still
     changing as new technology
     and research reveal new
     characteristics
Phylum Chrodata
• Characteristics
  – Presence of swim bladder or lung
  – Bones
  – Bony scales
  – Fin rays
2 major groups
• Subclass Chondrostei        • Subclass Neopterygii
  – Heterocercal tail            – Homocercal tails
  – Skeleton made mostly of         • Backbone does not
    cartilage                         extend into tail
  – Ganoid scales                – Cycloid OR Ctenoid
     • Armored appearance          scales
     • Florida Gar                  • Both are thinner and
                                      more flexible than ganoid
                                      scales
Body Shapes-determined by habitat
• Fusiform- streamlined
  shape for active
  swimmers
• Laterally compressed-
  flattened so can
  maneuver though corals
• Flattened: bottom-
  dwellers
• snakelike: burrowing
  fish
Respiration and Circulation
Respiration
• Gills: receive oxygen and remove CO2, and
  maintain salt balance
  – Made of gill filaments: blood flows in opposite
    direction of incoming H2O
• Water must continuously pass over gills
  – Meets with blood with lower O2 and higher CO2
     • Diffusion moves from where to where?????
  – Fish actually “pump” H2O over gills
Cardiovascular
• Close circulatory system: Heart, veins, arteries
  – Most complex we’ve seen so far!
  – 4 chambered heart
     • Draw diagram in your notes
• What does it mean to have
  an open circulatory system?
Swimming and Movement
Muscle Contractions

• W shaped bands of muscle
• Movement occurs when
  muscle contracts.
   – Alternate from one side to
     the other
   – Starts at anterior and travels
     to posterior end
• Contractions start at
  different areas in the body
  for different fish = different
  swimming patterns.
Staying neutrally bouyant
• Buoyancy
  – Swim bladder: gas filled sac; add and remove to
    adjust buoyancy
     • SCUBA divers must adjust air in BCD for same purpose
        – To go down: let air/gas out
        – To go up: add air/gas
Fish Coloration

5 important types you need to know
Important to fish survival
• Help the fish to
   – Find food
   – Communicate
   – Attract mates
   – Defend itself from
     predators
   – Recognize species
   – Conceal themselves
• Pigments: found in cells
  called chromatophores
Different types
• 1. Structural colors
   – Produced by light reflecting
     from crystals located on
     chromatophores
• 2. Obliterative
  Countershading
   – Found on fish living in
     pelagic zone (open ocean)
   – Dark on the top and white
     on the bottom
   – Why?
More types..
• 3. Disruptive Coloration
   – Distract predator
   – Lines, stripes, fake eyes
       • Trying to aim predator in
         the wrong direction
• Cryptic Coloration
   – Sneaky
   – Use colors to ambush prey
• Poster Colors
   – Bright, showy colors that
     advertise territorial
     ownership or sexual
     displays
Nervous System & Reproduction
Nervous System
• Brain, spinal cord, nerves
• Senses
  – Olfaction: sense of smell: olfactory pits (nostrils)
  – Taste: receptors on head, jaws, tongue, mouth
    and barbels on some fish (catfish)
  – Hearing: internal ears
  – Sight: Eyes Lack eyelids
     • Most set on sides of face: each eye see own
       independent view.
• Lateral Line: Detect movement in water
• Vast: depends on
  species
                              Reproduction
  – Internal and external
    sexual reproduction
  – Some care and protect
    young, others do not
• Perch: separate sexes
  – Males and females
    spawn eggs
  – Early spring in sandy,
    shallow sediments
  – Females lay more than
    20,000 eggs at a time;
    male comes afterward to
    fertilize
Perch Anatomy