Swimming and Morphology

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Swimming and Morphology
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Poikilothermia

• fish are cold-blooded
• can raise their body temp through exercise a
  little, but warmth soon lost at gills
• All organisms warm as they increase respiration
• Some fish like the tunas actually can regulate
  and use the heat liberated from their exercise to
  maintain body temp.
• Tunas have vast networks of blood vessels in
  their muscle that can be constricted or dilated
  to increase blood passage over muscle.
• This allows tuna to heat their bodies in cold
  water or cool them in warm waters.

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Ecomorphology

• Ecomorphology - The study of how abiotic or
  biotic factors influence the form or shape of an
  organism.
• Example Body shape types and swimming
• Fusiform idealized torpedo shape, lowest amount
  of drag (ex. Trout). Allows fast
  swimming/tolerance of flowing water.
• Dorso-ventrally compressed flattened on the back
  and belly (ex. Sturgeon, flounder, rays).
  Benthic species that lay on the bottom and/or use
  the current as a hydrofoil
• Laterally compressed flattened on the sides (ex.
  Centrarchids). Predators that need stability for
  attacks and maneuverability.

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Fish Locomotion

• Forces Involved in Fish Swimming
• Thrust - force that propels fish forward
• Drag - friction generated by moving object
  through water
• Gravity - partially counterbalanced by density of
  water
• Lift - upward force that counteracts gravity

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Thrust Generation in Fish

• Body waves - Anguilliform (eel-like)
• Partial body waves - Sub-carangiform and
  Carangiform (tuna-like)
• Caudal peduncle/fin beats - Ostraciform
  (boxfish-like and puffer-like)
• Medial fin waves - Amiiform - bowfin-like
• Pectoral fin beats - Labriform - wrasse-like

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Body Waves

• Lateral curvature in spine and musculature that
  moves in a posterior direction
• Starts with lateral displacement of head, and
  then passage of this displacement along the body
  axis to the tail
• Eel-like swimming
• Results in backward-facing wall of body that
  pushes back against the water

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Partial body waves

• body wave that begins posterior of head and
  increases with amplitude as it moves posteriorly
• decreases drag caused by leading edge that moves
  laterally in full body waves
• ultimate expression is that of tunas and jacks in
  which the wave STARTS at the caudal peduncle -
  THUNNIFORM - caudal fin typically deeply forked
  or lunate

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Caudal Fin Beats

• Sculling action of caudal fin
• Involves no body waves - body remains rigid -
  useful for odd-shaped fishes
• Differs mechanically from the caudal peduncle
  waves of tunas jacks

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Medial Fin Waves

• Body remains rigid, but medial fins (dorsal or
  anal) generate a series of waves that move
  posteriorly (forward thrust) or anteriorly
  (reverse thrust)
• Good for stalking prey (bowfin) or for moving
  without disrupting body musculature that serves
  as electric organ (knifefish)
• Also used for sculling - triggerfish others

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Pectoral Fin Beats

• Similar to rowing with laterally-positioned
  pectoral fins- often includes feathering as well
• Especially useful for fine maneuvering, e.g. by
  deep-bodied fishes
• Used almost exclusively as means of propulsion by
  wrasses and parrotfishes (families Labridae and
  Sparidae)

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How do fish generate a body wave?

• Need to understand structure of skeletal and
  muscular systems
• Skeleton - Mineral, rigid, strong, segmented
• Functions support, locomotion, protection
  (armor), mineral reserve (Calcium Phosphate)
• Composition cartilage, bone, connective tissue
  (fascia), skin

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Skeletal Organization

• Axial Skeleton
• Skull (cranium) -
• shield for brain, sense organs
• jaw attachment and movement
• branchial (gill) skeleton
• operculum
• Vertebral column - segmentation
• Pleural vertebrae - neural spine two pleural
  spines
• Caudal vertebrae - neural and hemal spine
• Articulation of vertebrae - for horizontal axis

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Other skeletal components

• Appendicular Skeleton
• pectoral girdle
• pelvic girdle
• pterygiophores - dorsal and anal fins
• fin rays and spines
• Membranous Skeleton
• mesentery around organs
• septa between muscles
• skin

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Fish Musculature

• Serial arrangement of muscle bundles
• segmentation is key to body waves
• Outer band of muscle bundles
• thin band on periphery of muscle mass
• red muscles
• Inner cones of muscle bundles
• thick set of complex stacked cones
• white muscles

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Red Muscle vs. White Muscle
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Red Muscle vs. White Muscle