BIOL 2003 Lecture Notes - Lecture 18: Teleost, Blue Shark, Axial Skeleton
Teleosts
November 6-9, 2015
Swim Bladder
• In bony fish to keep them neutrally buoyant so they do not sink
• Teleosts fish cannot take air into the bladder like ancestors but take gas into the bladder through a
cardiovascular organ that secretes oxygen into the swim bladder
o Specialized O2 secretion and absorption
• Derived from the lung
• Countercurrent exchanger works by dumung acid on the well oxygenated blood that is taking the
hemoglobin into the gas gland. Low pH drives the oxygen into the gas gland
• Changes volume as fish moves up and down water
o Volume decreases when going into deeper water
o Fish becomes more dense and negatively buoyant
o Therefore more gas must be secreted into the bladder for fish to move back up
o Membrane can open to allow the absorption of the gas back into circulation to stop expanding the
swim bladder/
• Tuna do not have gas chamber because they would expand too quicky?
Hearing in Fish: Weberian ossicles
• Not in all bony fish – 8000 species
• Catfish, carp and relatives
• Vibrations in the water cause vibration in the swim bladder that is larger than the movement of water
• There are specialized tiny bones that run from the swim bladder to the tiny head which contain semicircular
cannels, the sacs pick up which way is up
• Virbrations are transmitted through the fish to the swim bladder, the interface amplifies the vibrations and
transports the vibrations to the inner ear where they cause vibrations within the inner ear
• Weberian ossicles allow for hearing; extends frequency in a range that they can hear
Generic “fish shape”
• Streamlined - need less energy to move with this shape
• Shape adapted to lowest drag and ability to move forward
• Most musculature is associated with the vertebrae (axial skeleton)
o Myomeres are units of the muscle
o Contraction of the myomeres create a wave through the fish and allow them to control their
movements
o Weird shape gives smoother movement
• Most have a more standard fish shape with minor modification
• To thrust forward the myomeres on one side contract which bends body and creates a curve that moves
down the length of body while a segment in between pushes perpendicularly against the water
o Creates 45 degree reactive force and push opposite eachother
o Creates push forward with a lateral force at a 90 degree angle
o The lateral force is cancelled by the reactive and pushing force to allow the fish to thrust forward
o Tail generates thrust against outside world in some fish that is modified – therefore in fast moving
fish wave is larger in tail to minimize drag
Undulation in Chondrichthyes
• Moving wave through body from the head to tail (ex. Blue shark)
• Pectoral fin undergoes undulation in rays instead of body surface
Bowfin: *not a teleost fish
• Undulation in dorsal fin from the front to back and body is kept rigid
• Night fish
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Document Summary
Undulation in chondrichthyes: moving wave through body from the head to tail (ex. Blue shark: pectoral fin undergoes undulation in rays instead of body surface. Bowfin: *not a teleost fish: undulation in dorsal fin from the front to back and body is kept rigid, night fish. Butterfly, trunkfish, angelfish: small mouth sucks in very small food particles from water or substrate, small area creates efficient suction. Big food big mouth less suction ram feeding: fish moves forward at the same time the mouth opens and suction is developed, ex. Alligator fish eating a rock hind: ex. Sculpin eating another: ram-suction feeding in tarpon, opens mouth and sucks in small fish when it lunges toward prey, take 220 milliseconds. Crushing hard prey: wolf eel: modifications allow them to consume hard-bodied invertebrates, big heavy, reinforced bones different than haddock skull, huge jaw + crushing, strong teeth, derived from skull with mobile elements structurally reinforced. Pharyneal jaws: separating food from food processing: ex.
