Why so many Teleost fish?

Key adaptations
1. Cycloid and ctenoid scales
2. Increased speed and mobility
  1. Bony endoskeleton, matrix calcium phosphate
  2. Gas filled pouch off esophagus (swim bladder, lungs)
  3. Flattened scales
  4. Mucus glands reduce drag
3. Homocercal tails
4. increased efficiency: gas reabsorption & secretion
  1. Operculum: bony plate covering gills, attached muscles (ventilation)
5. Changes in jaw suspension
  1. Progressive specialisation jaw musculature & skeletal
Tails and Scales
1. Tails
  1. Heterocercal
    1. Vertebrae into lobe
      1. Upper caudal lobe larger: EPICERCAL
      2. Lower caudal lobe larger: HYPOCERCAL
  2. Homocercal
    1. No vertebrae extension
      1. Even lobes. Variety of shapes
  3. Diphycercal
    1. Vertebrae all the way to tip
2. Scales
  1. Placoid
    1. conical, tooth like
  2. Ganoid
    1. Diamond, ganoine + bone
  3. Clycoid/Ctenoid
    1. Thin, flexible, overlap
Circulation
1. Single cirulatory system
  1. 2 Chambered heart
2. Atrium -> Ventricles -> Gills
  1. O2 into blood CO2 out
  2. O2 rich -> Body -> Heart
    1. Capillary bed drops in pressure
3. Swimming motion aids circulation
4. Gills
  1. Increased SA - Lamellae/gill filaments
    1. Increased gaseous exchange - ~80%
  2. Countercurrent flow
Swim bladder/neutral buoyancy
1. Heavier than water so need to be more buoyant
  1. Sharks - heterocercal tail
  2. Fish - gas filled swim bladder
2. Physostomous - pneumatic duct
  1. Gulp air - increased volume
3. Physoclistous - no pneumatic duct
  1. Ovale valve open - O2 moves into blood
4. Both swim bladders have:
  1. Gas gland
    1. lactic acid - O2 release
  2. Rete mirabile
    1. capillary network
Osmotic regulation
1. Vertebrate kidney
  1. Tubular nephrons. Salts, H2O metabolites
  2. 1st blood
    1. Glomerulus
      1. Ultrafiltrate
        Processed
        Glucose, amino acids & H2O
        Remainder urine
2. Stenohaline
  1. Tolerates moderate changes in salinity
3. Euryhaline
  1. Tolerates large changes in salinity
4. Freshwater fish
  1. Hyperosmolal
    1. Lose salts (diffusion)
    2. Gain water (osmosis)
    3. Lots of dilute urine
  2. Large Glomerulus
    1. Chloride cells in gills uptake
  3. Hyperosmotic regulator
5. Saltwater fish
  1. Hyposmolal
    1. Lose water, gain salts
  2. Drink lots of sea water
  3. Small glomerulus
  4. Salt excretory glands
  5. Hypo-osmotic regulator
Reproduction
1. Mass spawning e.g. cod
  1. Elaborate courtship
2. Ovoparity, ovoviviparity and viviparity
3. Pelagic eggs: small, buoyant, transparent. Little yolk
4. Benthic eggs: larger, non-buoyant, adhesive & yolky
5. Some spp larval stage then metamorphosis e.g. eels
Migration
1. Catadromous
  1. from fresh water to marine to spawn
2. Semelparity
  1. Spawn and die
3. Iteroparity
  1. Multiple breeding
4. Anadromous
  1. Live in sea, FW to spawn

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Why so many Teleost fish?

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	Created by Litty Carter over 11 years ago