LECTURE 12 - OUTLINE · LECTURE 12 - OUTLINE Locomotion 2. Red Muscle 4. Modes of Swimming -...

1

LECTURE 12 - OUTLINE

Locomotion

2. Red Muscle

4. Modes of Swimming

- General

1. General

Muscular System

3. White Muscle

Locomotion

- Thunniform

5. Drag

BIOL 4340 – Lecture 12 - 1

- usually 2 sets of myomeres per vertebra, but may span 3 - 12

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


2

White Muscle

Red Muscle

Pink Muscle

Vertical Septum

Horizontal Septum

Muscular System

EpaxialMuscles

HypaxialMuscles- internally, myomeres

connected to vertical

and horizontal septa

- about 40-60% of fish

weight is locomotor

musculature

Vertebral centrum

- red and pink muscle

lie in a lateral band

along the mid-line of

the body


Muscular System

- capillary infused, high concentrations of O2-binding pigments

Red Muscle:

- Haemoglobin (blood) - Myoglobin (muscle tissues)

Prolonged or Sustained Swimming:

- swimming that can be maintained for an indefinite period

(i) longer than 200 minutes

(ii) does not involve fatigue

- utilizing aerobic metabolism for prolonged/sustained swimming

- foraging - station holding - schooling

- cruising (in negatively buoyant fish) - migration

- numerous large mitochondria, high oxidative enzyme activity

and abundant lipid and glycogen stores

- swimming that can be maintained from 20 sec – 200 min


3

Muscular System

- collapse, inability to maintain a given swimming speed

Ucrit = Critical Swimming Speed

- fish subjected to a stepwise increase in water velocity

(forced swimming speed) until fatigue occurs

- Ucrit computed from max. speed achieved prior to fatigue

Fatigue & Ucrit

(max. velocity a fish can maintain for a precise period of time)


Muscular System

Fatigue & Ucrit

Time between increments = 60 min

Max. swimming speed with no fatigue = 10 cm/sec

Time to fatigue @ 12 cm/sec = 30 min

Velocity increments = 2 cm/sec

Ucrit = 10 + [(12-10) x 30/60]

Ucrit = 11 cm/sec [expressed as l sec-1]

body length (cm)


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Muscular System

Fatigue & Ucrit

Time between increments = 60 min

Max. swimming speed with no fatigue = 10 cm/sec

Time to fatigue @ 12 cm/sec = 30 min

Velocity increments = 2 cm/sec

Ucrit = 10 + [(12-10) x 30/60]

Ucrit = 11 cm/sec

Constraints on Performance

Biological Environmental

- fish size (length and/or wt)

- nutritional status

- health/disease

- temperature

- water O2 content

- pollution

[expressed as l sec-1]


Muscular System

- 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

Red Muscle:


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Muscular System

- 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

Red Muscle:


Muscular System

- poor blood supply & lacks O2-binding pigments (e.g. myoglobin)

White Muscle:

- contraction not dependent on O2 supply

Burst Swimming:

- rapid movement of short duration and high speed

(i) maintained for less than 20 sec

(ii) subdivided into acceleration and sprint

- utilizes anaerobic metabolism, converting glycogen to lactate

- most useful for burst swimming

- few smaller mitochondria, enzymes of anaerobic glycolysis


6

Locomotion: modes of forward swimming

- contributions of body andfins indicated by shading

Undulation

- serpentine with more thanone wavelength present

Oscillation

- rigid “wig wag” or fan-likemotion

4 basic modes

1. Anguilliform

2. Subcarangiform

3. Carangiform

4. ThunniformBIOL 4340 – Lecture 12 - 11


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)

Aspect ratio = fin area

(fin height)2

narrow necking


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Thunniform Swimming

Mackerel

Tuna



Thunniform Swimming

- thrust generated exclusively by extremely narrow

caudal peduncle and high stiff caudal fin

- muscle mass delivers propulsive force via a system of

tendons running to the posterior vertebral column

- vertebrae of caudal peduncle form a rigid unit, with

lateral keels, peduncular & post-peduncular joint


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Thunniform SwimmingPOT: Posterior Oblique TendonsAOT: Anterior Oblique Tendons


GLT: Great Lateral Tendon


Thunniform Swimming:

Minimizing Drag

1. Viscous drag

- friction between body & water

2. Inertial drag

- pressure differences created

by displacement of water(i) Body shape

(ii) Surface smoothness

- fusiform shape optimizes drag reduction

- resistance to motion through fluid

- thin body, inc. viscous drag

- small scales/scaleless- mucus

(i) Body shape

(ii) Speed

- thick body, inc. inertial drag


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Minimizing Drag Profile thickness = d/l

l = body length

d = body width 0.10 0.20 0.30 0.40 0.50

profile thickness (d/l)

rela

tive

dra

g

increased viscous dragincreased inertial dragd

l

d* = 0.25l

* at 1/3 length

from tip of snout

Optimal Profile Thickness




Minimizing Drag Profile thickness = d/l

l = body length

d = body width 0.10 0.20 0.30 0.40 0.50

profile thickness (d/l)

rela

tive

dra

g

d

l


LECTURE 12 - OUTLINE · LECTURE 12 - OUTLINE Locomotion 2. Red Muscle 4. Modes of Swimming -...

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