chapter 8public.wsu.edu/~rlee/ocean/chapt08blecture.pdfmarine fishes mola mola or sunfish •...

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Chapter 8 Chapter 8 Marine Fishes Marine Fishes Mola mola or Sunfish Heaviest bony fish in the world, up to 2300 kg Enlarged anal and dorsal fins Much of the skeleton is cartilagenous Spinal column is very short (1 inch) Eats jellyfish http://www.youtube.com/watch?v=73iY8cE wmGY Mola Mola Related to pufferfishes and trigger fishes Fish cardiovascular physiology

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Chapter 8Chapter 8

Marine FishesMarine Fishes

Mola mola or Sunfish

• Heaviest bony fish in the world, up to 2300

kg

• Enlarged anal and dorsal fins

• Much of the skeleton is cartilagenous

• Spinal column is very short (1 inch)

• Eats jellyfish

• http://www.youtube.com/watch?v=73iY8cE

wmGY

Mola Mola

• Related to pufferfishes and trigger fishes

Fish cardiovascular

physiology

Fish GillsFish Gills

•• The construction of the gill is the same in all fish The construction of the gill is the same in all fish –– gill gill arch supports the entire structure, gill rakers are on the arch supports the entire structure, gill rakers are on the forward surface of the gill arch and gill filaments trail forward surface of the gill arch and gill filaments trail behind the gill arch behind the gill arch

•• Like in the human lung, exchange of oxygen and carbon Like in the human lung, exchange of oxygen and carbon dioxide takes place on these surfacesdioxide takes place on these surfaces

•• Gill Gill rakersrakers can also function in filter feedingcan also function in filter feeding

The Circulatory SystemThe Circulatory System

•• Fish have a two chambered heart that Fish have a two chambered heart that

serves to pump blood throughout the body serves to pump blood throughout the body

(in contrast to the 4 chambered heart seen (in contrast to the 4 chambered heart seen

in mammals)in mammals)

•• A system of arteries, veins and capillaries A system of arteries, veins and capillaries

takes blood to the body tissues and takes blood to the body tissues and

returns it for rereturns it for re--oxygenation by the gill oxygenation by the gill

filamentsfilaments

Fish locomotion

Swimming PatternsSwimming Patterns

•• Fish exhibit an Fish exhibit an ““ss--shapedshaped”” swimming swimming

patternpattern

•• Bands of muscle along the body called Bands of muscle along the body called

myomeres drive this swimming motionmyomeres drive this swimming motion

•• Depending on the type of fish, different Depending on the type of fish, different

fins may be used primarily for the forward fins may be used primarily for the forward

movementmovement

Swim tunnel

http://www.youtube.com/watch?v=P-c-EXmTmQY

• http://www.youtube.com/watch?v=Uw13qOnDVLE

Eel anguilliform locomotion Studying swimming hydrodynamics

Some biomechanics of swimming

• Burst swimming is in the range of 5-10 body lengths per second

• Drag increases as the square of velocity.

• Therefore a 2 m tuna swimming at 20 m/sexperiences 4 times more drag than a 1 m tuna swimming at 10 m/s

• Drag on a rigid body is less than on a flexible body

– “kick and glide” is a way to take advantage of this

Thunniform swimming

• Billfishes, tunas, some sharks

• Stiff caudal fins, high aspect ratio (crescent shaped)

• 90% of thrust comes from the caudal fin.

• Stiff vertebral column

• Head does not move side to side. Caudal fin acts like a “propeller”

• Tendons attach body musculature to caudal peduncle in some cases runs over the peduncle like a line over a pulley

• Fins can be depressed into grooves and recesses.

• Bulge of eye is streamlined with “adipose eyelids”

Caudal peduncle

Bluefin thunniform swimming

• http://www.youtube.com/watch?v=s272wD

RXkVw

MIT robotuna

• overall goal of developing a better propulsion system for autonomous

underwater vehicles, or AUVs

Biochemical adaptation to fast swimming

• Tunas have some of the highest levels of enzymes for glycolysis and aerobic respiration

• Lactic acid is the endproduct of glycolysis and sprinting, causes a drop in pH if sprinting is

prolonged

• In tunas the muscle pH is buffered by amino

acids, particularly histidine

• Marine animals in general are rich in free amino

acids including glutamate, glycine, and taurine.

Generating lift

Swimming PatternsSwimming Patterns

•• In sharks, a swim bladder is absent (although In sharks, a swim bladder is absent (although

there is a large lipidthere is a large lipid--rich liver to help in rich liver to help in

buoyancy) buoyancy) –– therefore, sharks tend to sink when therefore, sharks tend to sink when

not in motion and there is no lift from the swim not in motion and there is no lift from the swim

bladder while swimming eitherbladder while swimming either

•• Also their blood is full of ureaAlso their blood is full of urea

•• While swimming, sharks are aided by the While swimming, sharks are aided by the ““liftlift””

provided by the position and stiffness of the provided by the position and stiffness of the

pectoral finspectoral fins

Swimming PatternsSwimming Patterns

•• In bony fish, pectoral fins are not needed for lift In bony fish, pectoral fins are not needed for lift and thus are normally not stiff in construction and thus are normally not stiff in construction (exception: fast swimming species like tuna, (exception: fast swimming species like tuna, billfish, etc)billfish, etc)

•• In contrast, the pectoral fins in many bony fins In contrast, the pectoral fins in many bony fins are flexible and used for maneuverabilityare flexible and used for maneuverability

•• In some slowerIn some slower--swimming species, forward swimming species, forward movement is mainly provided primarily by the movement is mainly provided primarily by the pectoral finspectoral fins

Another cool type of fish:

Billfishes

Billfishes http://www.youtube.com/watch?v=B2kQF7eWkIs

Behaviors in FishBehaviors in Fish

•• SchoolingSchooling

–– Schooling is used by a wide variety of fishSchooling is used by a wide variety of fish

–– Schooling makes it possible for a group of Schooling makes it possible for a group of smaller fish to appear much larger (as thus smaller fish to appear much larger (as thus avoid detection by predators), not the case in avoid detection by predators), not the case in the videothe video

–– May be May be hydrodynamicallyhydrodynamically more efficientmore efficient

–– It also makes it harder for a predator to It also makes it harder for a predator to capture any one fishcapture any one fish

–– Because of this, many fish school as juvenilesBecause of this, many fish school as juveniles

–– About 4000 species school as adultsAbout 4000 species school as adults

Swordfishes also have heated brains and eyes

• Specialized heating system warms brain and eye up to 10-15

degrees C above water temperature

Some deep sea fishes

• Also called midwater or mesopelagic

• Many filter plankton using their gill rakers

• Others are predators with extreme adaptations for prey capture

Myctophids (lantern fishes)

• One of the most numerous of all fishes

Cyclothone (bristlemouths)

• This genus may contain more individuals and biomass than any other fish genus

Hatchet fish

• Large tubular eyes pointed upwards

Snipe eel

• Tiny hooked teeth entangle prey

• 5 ft specimen weighs a few ounces

Chiasmodon (black swallower) viperfish

Dragonfish

• Red light organ under eye

Most Important Characteristics Most Important Characteristics

of Marine Fishof Marine Fish