morphologie des poissons. phylum chordata subphylum vertebrata class agnatha class chondrichthyes...

Morphologie des poissons

Phylum ChordataSubphylum Vertebrata

Class AgnathaClass ChondrichthyesClass OsteichthyesClass AmphibiaClass ReptiliaClass AvesClass Mammalia

Classification Scheme of the Vertebrates

Chordate Characteristics

Placoderm(395-345)

lamprey & hagfish

Ost

raco

derm

(51

0-=

350

myb

p)

Ost

eich

thye

s (3

95)

Chondrichthyes (370)

(360)

Jaw Development

agnathostome gnathostome

1st appeared 400 mya

Basic AnatomyClass Agnatha

• Possess medial nostril, medial fins, notocord rather than vertebral column

• 7 or more pr gill pouches present• Light sensitive pineal eye• Fertilization external• Cartilaginous skeleton• Lack jaws, paired fins, scales• GI track w/out stomach • Lampreys and hagfish• 100 species

Class AgnathaLamprey

ammocoetes

Class AgnathaHagfish

Basic AnatomyClass Chondrichthyes

Sharks, skates, rays

Basic AnatomyClass Chondrichthyes

• Posses jaws with teeth, cartilaginous skeleton, paired fins• Scales (denticles) have same origin and composition as teeth• Possesses 5-7 gills• Spiral valve intestine• Ureoosmotic strategy• Electroreception• Lateral line• No swim bladder• Heterocercal tail• Relatively unchanged (480 mybp)

Sharks, skates, rays

Basic Anatomy

Basic AnatomyClass Osteichthyes

Basic AnatomyClass Osteichthyes

• Posses jaws with teeth, bony skeleton, paired fins• 4 paired gill arches covered by operculum• Intestine- simple, no spiral valve• Swim bladder• Lateral line• Homocercal tail• Scales- cycloid, ctenoid

Basic Anatomybony fish

anus

Internal Anatomy

Common Measurements

Basic AnatomyBasic AnatomyCoelacanth

• Swim bladder modified to lungs• Paired appendages• Spiral valve intestine• Ureoosmoic strategy• Electric sense• Bony head• Scales and teeth• May have given rise to terrestrial tetrapods

General Life Style Categoriesa. pelagic cruisers1. occurring in water column far away from the bottom (benthic)

environment2. often referred to as "blue water"3. includes tuna, billfish, blue sharks, mackerel sharks (great

whites and mako sharks)

Fish Adaptations and Life Styles

b. demersal

1. bottom-associated fishes, but not usually sitting on the bottom

2. rely on the benthic environment as a source of food, place to reproduce, and/or place of refuge, etc.

3. includes most reef fishes (e.g., butterfly fishes, surgeon fishes, wrasses, parrot fishes, etc.)

c. benthic

1. bottom-dwelling fishes that spend the majority of time sitting on the bottom

2. includes flatfishes, lizard fishes, many scorpion fishes, many hawkfishes, gobies, etc.

tuna

1) fusiforma) = torpedo-shaped b) allows minimal drag while swimmingc) best shape for a pelagic cruise

Body shapeBody shape

2) compresseda) laterally flattened (e.g., butterflyfishes &

surgeonfishes)b) allows for maneuverability in surge environmentsc) useful for demersal fishes that hover above the reefd) exception seen in flatfishes that lie on one side of the

body as benthic fishes

3) elongated or attenuateda) long body (e.g., trumpetfish, cornetfish, eels)b) seen in demersal fish that either hover

motionless in the water)c) seen also in benthic fishes (e.g., eels) that

hide in holes in the reef

4) depresseda) dorso-ventrally flattened (e.g., frogfishes,

scorpionfishes & gobies)b) broad ventral surface facilitates resting on

the bottomc) seen in many benthic fishes

Body Coloration

1) source of colora) pigment color - chromatophores for yellows,

reds, oranges, browns, & blacksb) structural color - iridophores (reflection) &

light refraction for blues, silvers, & rainbows

2) patterns

a) countershading

1) dark blue or black dorsally, white or silvery ventrally

2) results in blue water "camouflage“

3) observed most frequently in pelagic cruisers

b) camouflage1) matching the background coloration2) usually involves having irregular dark

blotches and spots3) typically seen in benthic fishes, especially

benthic ambush predators (e.g., frogfishes, gobies, & many scorpionfishes)

4) some fishes (e.g., flatfishes) may exhibit rapid color changes in response to different backgrounds

b) camouflage

5) matching downwelling light

Cookie cutter shark

Hatchet fish

c) disruptive coloration

1) color pattern breaks up the silhouette of the fish

2) may involve dark bars across the eye and tail region

3) seen in many demersal fishes such as butterfly fishes

d) bars and stripes1) bars are vertical (e.g., manini)2) stripes are horizontal (e.g., ta'ape)3) seen frequently in schooling demersal

fishes4) may confuse potential predators by

making it difficult to select individual prey from the school

 e) misdirection

1) false eye spots, etc.2) observed in many demersal butterfly fishes

f) advertising coloration1) bright, obvious color patterns2) possible functions

a) advertising a cleaning station (e.g., cleaner wrasses)

b) advertising a warning (e.g., nohu)c) advertising for mates (e.g., male

parrotfishes)

Hawaiian cleaner wrasse Nohu

g) mimicry1) imitating other creatures2) seen in a few demersal and benthic fishes3) examples

a) blenny (Aspidontus taeniatus) mimics cleaner wrasses

b) shortnose wrasse mimics Potter's angel which sports a defensive spine

g) mimicry4) leafy sea dragon (Australia)

h) uniform red coloration

1) most often observed in deep-dwelling or night active demersal fishes

2) examples include opakapaka, oweoweo, menpachi, & squirrelfishes

i) noctural versus diurnal color changes

j) male versus female color differences

k) juvenile versus adult color differences

Bluehead wrasse

Dragon wrasse

Stoplight parrotfish

1. vision 2. hearing – inner ear; swim bladder

amplifies in some fish 3. olfaction –  olfactory sacs; taste buds 4. lateral lines of fish – detect vibrations

in the water 5. Electrical Sense: ampullae of

Lorenzini (sharks and rays) – sensitive to electric currents

6. geomagnetic sensory system (long distance migration- tuna)

• Locate prey• Find a mate• Migration

• Find a mate

1. Anadromous- salmona) can return to the same stream in which

they hatched b) may use land features, currents, salinity,

temperature, the sun or magnetic field to get close to land

c) sense of smelld) die after spawning e) young return to the sea

2. catadromous –freshwater eels 3. Extensive migration-anatomical basis for

magnetotaxis -- magnitite

pores

• Detects weak magnetic fields produced by other fish• May also detect geomagnetic orientation

Ampullae of Lorenzini

Paddlefish

knifefish

Electric eel (really a knifefish) Electric ray

The source of propulsion for virtually all fish comes from:

1. Undulation of the body

2. Paired Fins: • Pectoral • Pelvic

3. Unpaired Fins: • Caudal • Dorsal • Anal

4. A combination of the above

Types of Fins

Anguilliform swimming(Undulation)

Dorsal & Anal Fin Propulsion

Anal Fin Propulsion

Black ghost knifefish

Pectoral Fin Propulsion

Dorsal fin

Bowfin

Sea horse

Knifefish

Pectoral Fin

Frogfish

Walking catfish

Mudskipper

Sphere

Disk

teardrop

Laminar flow and turbulence

Hydrodynamics:Effects of shape on drag

Slowest FishEwa Blenny 0.5 mph

Fastest Fish

43.4 mph leaping

68 mph, leaping

Blue-fin tuna

Sailfin

Tuna- long distance swimmer

Snapper- short bursts

Countercurrent Exchange

Respiratory and Circulatory System

Ram Jet Ventilation

Buccal Pump Ventilation

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Feeding Behavior

Suction feedingSlingjaw wrasse

• Blubber

• Swim bladder

• Pneumatophore

Organisms adaptation to buoyancy in water

• Air chambers

• Large liver & heterocercal tail

• Buoyancy Compensator Device

(BCD)

Organisms adaptation to buoyancy in water

Physostomous Gas Bladder

air

Rete mirable

Physoclist gas bladder

• Missing in fish that swim fast or

change depth rapidly (Tuna)• Benthic fish (blennies, hawkfish,

stonefish…)• Sharks, skates, rays• Deep water fish

Osmoregulation- the control of the concentration of body fluids.

Diffusion- movement of substance from an area of greater concentration to an area of lower concentration

Osmosis- diffusion of water through a semipermeable membrane

Marine Fish: hypoosmotic

H2O continually leaves body

continually drinks seawater

excretes salt through gills produces small

amts of dilute urine

Less salt than external

environment

Freshwater Fish: hyperosmotic

H2O continually enters body

does not drinks water

produces large amts of dilute urine

More salt than external

environment

Shark and Coelacanth: ureoosmotic

Maintains high levels of urea and TMAO in blood

excretes salt through rectal gland

coelacanth

Hagfish: ionosmotic

nonregulator

Seawater concentration = internal concentration

Osmolarity- measure of total solutes(dissolved particles)

Ions FW m osmol/l SW m osmol/lNa+ 1 470 Cl- 1 550Ca++ variable 10 Total 10 1000

Osmolarity in Freshwater and Saltwater

  Habitat Na+ Cl- Urea

seawater sw 478 558  

hagfish (Myxine) sw 537 542  

lamprey fw 120 96  

Goldfish (Carassius) fw 115 107  

Toadfish (Opsanus) sw 160    

Crab-eating frog (Rana) sw 252 227 350

Dogfish sw 287 240 354

freshwater ray fw 150 149 <1

coelacanth sw 197 199 350

Inquiry

1. Describe the uses of a countercurrent exchange system.

2. Describe 4 strategies of osmoregulation.3. Describe the differences between the

two types of swim bladders.4. What is the difference between buccal

pump and ram jet ventilation?5. Describe the difference between

anadromous and catadromous.