LECTURE 12 - OUTLINE
Locomotion
Muscular System
1. General
2. Red Muscle
3. White Muscle
Locomotion
4. Modes of Swimming
- General
- Thunniform
5. Drag
BIOL 4340 – Lecture 12 - 1
Muscular System
- muscle mass divided vertically into myomeres (or myotomes)
- myomeres separated by septa (connective tissue)
- anteriorly, musculature connected to head & pectoral girdle
- posteriorly, to caudal fin or tendons connected to caudal fin
- usually 2 sets of myomeres per vertebra, but may span 3 - 12
BIOL 4340 – Lecture 12 - 2
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Muscular System
Vertical Septum
- about 40-60% of fish
weight is locomotor
musculature
Epaxial
Muscles
White Muscle
Red Muscle
- red and pink muscle
lie in a lateral band
along the mid-line of
the body
Pink Muscle
Hypaxial
- internally, myomeres Muscles
connected to vertical
and horizontal septa
Horizontal
Septum
Vertebral
centrum
BIOL 4340 – Lecture 12 - 3
Muscular System
Red Muscle:
- capillary infused, high concentrations of O2-binding pigments
- Haemoglobin (blood)
- Myoglobin (muscle tissues)
- numerous large mitochondria, high oxidative enzyme activity
and abundant lipid and glycogen stores
- utilizing aerobic metabolism for prolonged/sustained swimming
Prolonged or Sustained Swimming:
- swimming that can be maintained from 20 sec – 200 min
- swimming that can be maintained for an indefinite period
(i) longer than 200 minutes
(ii) does not involve fatigue
- foraging
- station holding
- schooling
- cruising (in negatively buoyant fish) - migration
BIOL 4340 – Lecture 12 - 4
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Muscular System
Fatigue & Ucrit
- collapse, inability to maintain a given swimming speed
Ucrit = Critical Swimming Speed
(max. velocity a fish can maintain for a precise period of time)
- fish subjected to a stepwise increase in water velocity
(forced swimming speed) until fatigue occurs
- Ucrit computed from max. speed achieved prior to fatigue
BIOL 4340 – Lecture 12 - 5
Muscular System
Fatigue & Ucrit
Time between increments = 60 min
Velocity increments = 2 cm/sec
Max. swimming speed with no fatigue = 10 cm/sec
Time to fatigue @ 12 cm/sec = 30 min
Ucrit = 10 + [(12-10) x 30/60]
Ucrit = 11 cm/sec [expressed as l sec-1]
body length (cm)
BIOL 4340 – Lecture 12 - 6
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Muscular System
Fatigue & Ucrit
Time between increments = 60 min
Velocity increments = 2 cm/sec
Max. swimming speed with no fatigue = 10 cm/sec
Time to fatigue @ 12 cm/sec = 30 min
Ucrit = 10 + [(12-10) x 30/60]
Ucrit = 11 cm/sec [expressed as l sec-1]
Constraints on Performance
Biological
Environmental
- fish size (length and/or wt)
- nutritional status
- health/disease
- temperature
- water O2 content
- pollution
BIOL 4340 – Lecture 12 - 7
Muscular System
Red Muscle:
- by cross-section, 5 to 15 % muscle mass in most species
- some species 0 % while others + 15 %
Pollock (Gadus virens)
~ 11% red muscle
Boarfish (Capros aper)
~ 0.5% red muscle
Ratfish
(Chimaera monstrosa):
~ 0.6% red muscle
BIOL 4340 – Lecture 12 - 8
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Muscular System
Red Muscle:
- by cross-section, 5 to 15 % muscle mass in most species
- some species 0 % while others + 15 %
Thunniform fishes
- carry red muscle deep in body core
- aids stiff body swimming mode
- permits conservation of metabolic heat, allowing;
(i) faster muscular contraction
(ii) greater swimming velocities
BIOL 4340 – Lecture 12 - 9
Muscular System
White Muscle:
- poor blood supply & lacks O2-binding pigments (e.g. myoglobin)
- few smaller mitochondria, enzymes of anaerobic glycolysis
- contraction not dependent on O2 supply
- utilizes anaerobic metabolism, converting glycogen to lactate
- most useful for burst swimming
Burst Swimming:
- rapid movement of short duration and high speed
(i) maintained for less than 20 sec
(ii) subdivided into acceleration and sprint
BIOL 4340 – Lecture 12 - 10
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Locomotion: modes of forward swimming
- contributions of body and
fins indicated by shading
Undulation
- serpentine with more than
one wavelength present
Oscillation
- rigid “wig wag” or fan-like
motion
4 basic modes
1. Anguilliform
2. Subcarangiform
3. Carangiform
4. Thunniform
BIOL 4340 – Lecture 12 - 11
Locomotion: modes of forward swimming
Thunniform Swimming
- thrust generated exclusively by extremely narrow
caudal peduncle and high stiff caudal fin
- heavy, rigid and streamlined body prevents
sideways recoil (side slipping)
narrow necking
Aspect ratio =
(fin height)2
fin area
BIOL 4340 – Lecture 12 - 12
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Locomotion: modes of forward swimming
Thunniform Swimming
Mackerel
Tuna
BIOL 4340 – Lecture 12 - 13
Locomotion: modes of forward swimming
Thunniform Swimming
- thrust generated exclusively by extremely narrow
caudal peduncle and high stiff caudal fin
- vertebrae of caudal peduncle form a rigid unit, with
lateral keels, peduncular & post-peduncular joint
- muscle mass delivers propulsive force via a system of
tendons running to the posterior vertebral column
BIOL 4340 – Lecture 12 - 14
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Locomotion: modes of forward swimming
Thunniform Swimming
POT: Posterior Oblique Tendons
AOT: Anterior Oblique Tendons
GLT: Great Lateral Tendon
BIOL 4340 – Lecture 12 - 15
Locomotion: modes of forward swimming
Thunniform Swimming:
Minimizing Drag - resistance to motion through fluid
1. Viscous drag
2. Inertial drag
- friction between body & water
(i) Body shape
- thin body, inc. viscous drag
(ii) Surface smoothness
- small scales/scaleless
- mucus
- pressure differences created
by displacement of water
(i) Body shape
- thick body, inc. inertial drag
(ii) Speed
- fusiform shape optimizes drag reduction
BIOL 4340 – Lecture 12 - 16
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Locomotion: modes of forward swimming
Thunniform Swimming:
Minimizing Drag
Profile thickness = d/l
increased viscous drag
increased inertial drag
d
l
Optimal Profile
Thickness
d* = 0.25l
relative drag
* at 1/3 length
d = body width
l = body length
from tip of snout
0.10
0.20
0.30
0.40
profile thickness (d/l)
0.50
BIOL 4340 – Lecture 12 - 17
Locomotion: modes of forward swimming
Thunniform Swimming:
Minimizing Drag
Profile thickness = d/l
d
relative drag
l
d = body width
l = body length
0.10
0.20
0.30
0.40
profile thickness (d/l)
0.50
BIOL 4340 – Lecture 12 - 18
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