Chapt24 Fishes

8/19/2019 Chapt24 Fishes

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Copyright © The McGraw-Hill Companies, Inc. Permission required or reproduction or display.

Chapter 24

Fishes


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OverviewOverview

• ““Fish” has many usages extending beyond whatFish” has many usages extending beyond whatare actually considered fsh today (e.g. starfsh,are actually considered fsh today (e.g. starfsh,etc.).etc.).

• A modern fsh is an aquatic ertebrate with gills,A modern fsh is an aquatic ertebrate with gills,limbs (i! "resent) in the !orm o! fns, and usuallylimbs (i! "resent) in the !orm o! fns, and usuallywith a s#in coered in scales o! dermal origin.with a s#in coered in scales o! dermal origin.

• Fishes do not !orm a mono"hyletic grou".Fishes do not !orm a mono"hyletic grou".

• $he common ancestor o! fshes is also an ancestor $he common ancestor o! fshes is also an ancestoro! land ertebrates% there!ore in "ure cladistics,o! land ertebrates% there!ore in "ure cladistics,this would ma#e land ertebrates “fsh”&athis would ma#e land ertebrates “fsh”&anontraditional and aw#ward usage.nontraditional and aw#ward usage.

• 'ith oer ,*** liing s"ecies, fsh include more'ith oer ,*** liing s"ecies, fsh include more

s"ecies than all other ertebrates combined.s"ecies than all other ertebrates combined.


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+eriew+eriew

• $hey are ada"ted to lie in a medium ** $hey are ada"ted to lie in a medium **times more dense than air.times more dense than air.

• $hey can ad-ust to the salt and water balance $hey can ad-ust to the salt and water balanceo! their enironment.o! their enironment.

• $heir gills are ecient at extracting oxygen $heir gills are ecient at extracting oxygen!rom water that has /0*th the oxygen o! air.!rom water that has /0*th the oxygen o! air.

• A lateral line system detects water currentsA lateral line system detects water currents

and ibrations, a sense o! “distant touch.”and ibrations, a sense o! “distant touch.”• 1olution in an aquatic enironment both1olution in an aquatic enironment bothsha"ed and constrained its eolution.sha"ed and constrained its eolution.

• ““Fish” re!ers to one or more indiiduals o! oneFish” re!ers to one or more indiiduals o! ones"ecies% “fshes” re!ers to more than ones"ecies% “fshes” re!ers to more than one

s"ecies.s"ecies.


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HistoryHistory

• Fishes descended !rom an un#nown !ree2swimmingFishes descended !rom an un#nown !ree2swimming"rotochordate ancestor."rotochordate ancestor.

• 1arliest fsh2li#e ertebrates were a "ara"hyletic grou"1arliest fsh2li#e ertebrates were a "ara"hyletic grou"

o! agnathan fshes.o! agnathan fshes.3 Agnathans include extinct ostracoderms and liing hagfshesAgnathans include extinct ostracoderms and liing hagfshesand lam"reys.and lam"reys.

3 4agfshes lac# ertebrae and lam"reys hae rudimentary4agfshes lac# ertebrae and lam"reys hae rudimentaryertebrae.ertebrae.

3 Agnathans are included in sub"hylum 5ertebrata becauseAgnathans are included in sub"hylum 5ertebrata because

they hae a cranium and other !eatures.they hae a cranium and other !eatures.3 Agnathans are unique enough to be assigned in se"arateAgnathans are unique enough to be assigned in se"arate

classes.classes.

• 6emaining fsh hae "aired a""endages and -oin6emaining fsh hae "aired a""endages and -ointetra"ods as a mono"hyletic lineage o!tetra"ods as a mono"hyletic lineage o!

gnathostomes.gnathostomes.


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Fig.Fig.

• $hey a""ear in the8ilurian !ossil recordwith !ully !ormed

-aws, and nointermediates are#nown.• $he 9eonian iscalled the Age o!

Fishes.• +ne grou", the placoderms,became extinct in

the :arboni!erousand le!t no directdescendants.


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Fig.Fig.

7.7.


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4istory24istory2CartilaginousCartilaginous

FishesFishes• $he cartilaginous fshes lost the heay $he cartilaginous fshes lost the heay

dermal armor and ado"ted cartilage as thedermal armor and ado"ted cartilage as the

s#eleton.s#eleton.• $hey ;ourished during the 9eonian and $hey ;ourished during the 9eonian and:arboni!erous.:arboni!erous.

• $hey nearly became extinct at the end o! $hey nearly became extinct at the end o!the eso=oic, radiating to !orm a modern shar#

assemblage.assemblage.


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4istory24istory2AcanthodiansAcanthodians

• $hese fsh were well re"resented in $hese fsh were well re"resented inthe 9eonian but became extinct bythe 9eonian but became extinct by

the lower


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4istory24istory2Bony FishesBony Fishes

• $hese are the dominant fshes today. $hese are the dominant fshes today.

• $hey hae two distinct lineages? the $hey hae two distinct lineages? the

ray2fned fshes and the lobe2fnnedray2fned fshes and the lobe2fnnedfshes.fshes.

• $he ray2fnned fshes radiated to !orm $he ray2fnned fshes radiated to !orm

modern bony fshes.modern bony fshes.• @obe2fnned fshes are a relict grou"@obe2fnned fshes are a relict grou"

with !ew s"ecies today, but includewith !ew s"ecies today, but include

the sister grou" o! the tetra"odsthe sister grou" o! the tetra"ods


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Living Jawless FishesLiving Jawless Fishes

• @iing -awless fshes are re"resented by@iing -awless fshes are re"resented byhagfshes and lam"reys.hagfshes and lam"reys.

• About 7 s"ecies o! hagfshes are #nown andAbout 7 s"ecies o! hagfshes are #nown andabout 7/ s"ecies o! lam"rey are described.about 7/ s"ecies o! lam"rey are described.

• >embers o! both grou"s lac# -aws, internal>embers o! both grou"s lac# -aws, internalossifcation, scales or "aired fns.ossifcation, scales or "aired fns.

• Both grou"s share "oreli#e gill o"enings andBoth grou"s share "oreli#e gill o"enings and

an eel2li#e body.an eel2li#e body.• 4agfshes are least deried% lam"reys are4agfshes are least deried% lam"reys are

much closer to gnathostomes.much closer to gnathostomes.

• $here!ore, the grou"ing Agnatha is a $here!ore, the grou"ing Agnatha is a

"ara"hyletic assemblage o! -awless fshes."ara"hyletic assemblage o! -awless fshes.


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Class Myxini Hag!shesClass Myxini Hag!shes

• 4agfshes are entirely marine.4agfshes are entirely marine.

• $hey are scaengers and "redators o! $hey are scaengers and "redators o!

annelids, molluscs, dead or dying fshes,annelids, molluscs, dead or dying fshes,etc.etc.

• $he hagfsh enters a dead or dying animal $he hagfsh enters a dead or dying animalthrough an orifce or by digging insidethrough an orifce or by digging inside

using #eratini=ed "lates on its tongue tousing #eratini=ed "lates on its tongue toras" away bits o! ;esh.ras" away bits o! ;esh.

• Ct is nearly blind but can locate !ood by anCt is nearly blind but can locate !ood by an

acute sense o! smell and touch.acute sense o! smell and touch.


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FeedingFeeding

• $o "roide leerage, the $o "roide leerage, thehagfsh ties a #not in itshagfsh ties a #not in its

tail and "asses ittail and "asses it

!orward to "ress against!orward to "ress againstthe "rey.the "rey.

• 8"ecial glands along the8"ecial glands along thebody secrete ;uid thatbody secrete ;uid that

becomes slimy inbecomes slimy in

contact with seawater.contact with seawater.

• $he body ;uids o! a $he body ;uids o! ahagfsh are in osmotichagfsh are in osmotic

equilibrium withequilibrium with

seawaterseawater


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6e"roduction in 4agfshes6e"roduction in 4agfshes

• $he :o"enhagen Academy o! 8cience $he :o"enhagen Academy o! 8cienceoDered a "ri=e oer a century ago !oroDered a "ri=e oer a century ago !or

in!ormation on hagfsh breedingin!ormation on hagfsh breedinghabits% it remains unclaimed.habits% it remains unclaimed.

• Cn some s"ecies, !emales outnumberCn some s"ecies, !emales outnumber

males by /** to /.males by /** to /.• Females "roduce small numbers o!Females "roduce small numbers o!

sur"risingly large, yol#y eggs 2E cmsur"risingly large, yol#y eggs 2E cm

in diameter.in diameter.


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Class CephalaspidomorphiClass Cephalaspidomorphi??

@am"reys@am"reys

• $here are s"ecies o! lam"reys in orth $here are s"ecies o! lam"reys in orthAmerica% hal! belong to non"arasitic broo#2America% hal! belong to non"arasitic broo#2

dwelling s"ecies.dwelling s"ecies.• All lam"reys ascend !reshwater streams toAll lam"reys ascend !reshwater streams tobreed.breed.

• >arine !orms are anadromous, leaing the>arine !orms are anadromous, leaing thesea where they were adults to s"awnsea where they were adults to s"awnu"stream.u"stream.

• Cn orth America, all lam"reys s"awn inCn orth America, all lam"reys s"awn in

winter or s"ring.winter or s"ring.


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"eproduction and"eproduction and

#evelopment#evelopment

• >ales build a nest by>ales build a nest by

li!ting stones with theirli!ting stones with theiroral discs and usingoral discs and usingbody ibrations.body ibrations.

• $he !emale anchors to $he !emale anchors toa roc# and the malea roc# and the maleattaches to her head.attaches to her head.

• As eggs are shed intoAs eggs are shed intothe nest, the malethe nest, the male!ertili=es them% adults!ertili=es them% adultsdie soon therea!ter.die soon therea!ter.

• 1ggs hatch in two1ggs hatch in twowee# into uniquewee# into uniquelarae (ammocoetes).larae (ammocoetes).


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6e"roduction and6e"roduction and

9eelo"ment9eelo"ment• $he lara lies frst on its yol# su""ly $he lara lies frst on its yol# su""ly

and then dri!ts downstream to burrowand then dri!ts downstream to burrow

into sandy areas.into sandy areas.• $he lara is a sus"ension2!eeder until it $he lara is a sus"ension2!eeder until it

metamor"hoses in to an adult.metamor"hoses in to an adult.

• :hange to an adult inoles eru"tion o!:hange to an adult inoles eru"tion o!eyes, #eratini=ed teeth re"lacing theeyes, #eratini=ed teeth re"lacing thehood, enlargement o! fns, maturation o!hood, enlargement o! fns, maturation o!

gonads and modifcation o! gill o"enings.gonads and modifcation o! gill o"enings.


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$ea Lamprey %nvasion o&$ea Lamprey %nvasion o&

the 'reat La(es "egionthe 'reat La(es "egion

• o lam"reys were in the G. 8. Hreat @a#es west o!o lam"reys were in the G. 8. Hreat @a#es west o!iagara Falls until the 'elland 8hi" :anal was built iniagara Falls until the 'elland 8hi" :anal was built in/I./I.

• A century later, sea lam"reys were frst seen in @a#e 1rie,A century later, sea lam"reys were frst seen in @a#e 1rie,then s"read to all o! the G.8. Hreat @a#es in the /I7*s.then s"read to all o! the G.8. Hreat @a#es in the /I7*s.

• @am"reys "re!erred la#e trout and destroyed this@am"reys "re!erred la#e trout and destroyed thiscommercial s"ecies.commercial s"ecies.

• $hey then turned to rainbow trout, whitefsh, burbot, $hey then turned to rainbow trout, whitefsh, burbot,yellow "erch and la#e herring.yellow "erch and la#e herring.

• A!ter decimating these "o"ulations, they resorted toA!ter decimating these "o"ulations, they resorted tochubs and suc#ers.chubs and suc#ers.• $he lam"rey "o"ulations declined both !rom de"letion o! $he lam"rey "o"ulations declined both !rom de"letion o!

!ood and !rom control measures.!ood and !rom control measures.

• :hemical laricides were used in s"awning streams%:hemical laricides were used in s"awning streams%

release o! sterile males is also being used.release o! sterile males is also being used.


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Class ChondrichthyesClass Chondrichthyes

Cartilaginous FishesCartilaginous Fishes

• early J* liing s"ecies are in the classearly J* liing s"ecies are in the class:hondrichthyes.:hondrichthyes.

• Although a smaller and more ancient grou", theirAlthough a smaller and more ancient grou", theirwell2deelo"ed sense organs, "ower!ul -aws andwell2deelo"ed sense organs, "ower!ul -aws and"redaceous habits hel"ed them surie."redaceous habits hel"ed them surie.

• Although calcifcation may be extensie, trueAlthough calcifcation may be extensie, truebone is com"letely absent throughout the class.bone is com"letely absent throughout the class.

• early all are marine% only s"ecies lieearly all are marine% only s"ecies lie"rimarily in !reshwater."rimarily in !reshwater.• A!ter whales, shar#s are the largest liingA!ter whales, shar#s are the largest liing

ertebrates, reaching / meters in length.ertebrates, reaching / meters in length.


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Fig.Fig.

7.E7.E


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$u)class *lasmo)ranchii$u)class *lasmo)ranchii

$har(s+ $(ates and "ays$har(s+ $(ates and "ays• $here are nine orders o! elasmobranchs with about $here are nine orders o! elasmobranchs with about

/J total s"ecies described./J total s"ecies described.

• +rder :archarhini!ormes contains the coastal tiger and+rder :archarhini!ormes contains the coastal tiger andbull shar#s and the hammerhead.bull shar#s and the hammerhead.

• +rder @amni!ormes contains large, "elagic shar#s such+rder @amni!ormes contains large, "elagic shar#s suchas the white and ma#o shar#.as the white and ma#o shar#.

• 9ogfsh shar#s commonly studied in com"aratie9ogfsh shar#s commonly studied in com"aratieanatomy classes are in the order 8quali!ormes.anatomy classes are in the order 8quali!ormes.

• $he order 6a-i!ormes includes s#ates, sawfsh rays, $he order 6a-i!ormes includes s#ates, sawfsh rays,electric rays, stingrays, manta rays K others.electric rays, stingrays, manta rays K others.• $here are authenticated cases o! attac#s by the great $here are authenticated cases o! attac#s by the great

white, ma#o, tiger, and hammerhead shar#s, andwhite, ma#o, tiger, and hammerhead shar#s, andcasualties are more common in tro"ical and tem"eratecasualties are more common in tro"ical and tem"erate

waters o! the Australian region.waters o! the Australian region.


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Form and FunctionForm and Function

• 8har#s are among the most grace!ully streamlined o!8har#s are among the most grace!ully streamlined o!fshes% the body is !usi!orm.fshes% the body is !usi!orm.• $he !ront o! the entral mouth is the "ointed rostrum. $he !ront o! the entral mouth is the "ointed rostrum.• $he tail has a longer u""er lobe% this "attern is called $he tail has a longer u""er lobe% this "attern is called

heterocercal.heterocercal.

• Fins include "aired "ectoral and "elic fns, one orFins include "aired "ectoral and "elic fns, one ortwo median dorsal fns, a median caudal fn, andtwo median dorsal fns, a median caudal fn, andsometimes a median anal fn.sometimes a median anal fn.


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Form and FunctionForm and Function• Cn males, the medial "art o! the "elic fn isCn males, the medial "art o! the "elic fn is

modifed to !orm a clas"er used in co"ulation.modifed to !orm a clas"er used in co"ulation.• $he lateral eyes are lidless% behind each eye is a $he lateral eyes are lidless% behind each eye is a

s"iracle, a remnant o! the frst gill slit.s"iracle, a remnant o! the frst gill slit.

• $he tough, leathery s#in has "lacoid scales that $he tough, leathery s#in has "lacoid scales that

reduce water turbulence.reduce water turbulence.• G""er and lower -aws are equi""ed with shar",G""er and lower -aws are equi""ed with shar",triangular teeth that are constantly re"laced.triangular teeth that are constantly re"laced.


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8enses8enses• 8har#s trac# "rey using8har#s trac# "rey using

sequence o! sensitie senses.sequence o! sensitie senses.

•


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9igestion9igestion• A lier and "ancreas o"en into the short,A lier and "ancreas o"en into the short,

straight intestine.straight intestine.

• $he s"iral ale in the intestine slows "assage $he s"iral ale in the intestine slows "assageo! !ood and increases absor"tie area.o! !ood and increases absor"tie area.

• $he rectal gland secretes sodium chloride and $he rectal gland secretes sodium chloride andin this regard assists the o"isthone"hric #idney.in this regard assists the o"isthone"hric #idney.


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+ther 8ystems+ther 8ystems

• $he heart chambers "roide the standard $he heart chambers "roide the standardcirculatory ;ow through gills and body.circulatory ;ow through gills and body.

• 1lasmobranchs retain nitrogenous1lasmobranchs retain nitrogenouscom"ounds in the blood to raise blood solutecom"ounds in the blood to raise blood soluteconcentrations and eliminate the osmoticconcentrations and eliminate the osmoticinequality between blood and seawater.inequality between blood and seawater.


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"eproduction and"eproduction and

#evelopment#evelopment• All chondrichtheans hae internal !ertili=ation%All chondrichtheans hae internal !ertili=ation%maternal su""ort o! the embryo is ariable.maternal su""ort o! the embryo is ariable.• $hose that lay large, yol#y eggs immediately a!ter $hose that lay large, yol#y eggs immediately a!ter

!ertili=ation are oi"arous.!ertili=ation are oi"arous.3 8ome oi"arous shar#s and rays lay a ca"sule or “mermaidLs8ome oi"arous shar#s and rays lay a ca"sule or “mermaidLs

"urse” that catches onto #el" with tendrils."urse” that catches onto #el" with tendrils.3 $he embryo is nourished !rom the yol# !or u" to two years $he embryo is nourished !rom the yol# !or u" to two years

be!ore hatching as a miniature adult.be!ore hatching as a miniature adult.

• 8har#s that retain embryos are ooii"arous i! the8har#s that retain embryos are ooii"arous i! theembryo is nourished by yol#.embryo is nourished by yol#.

• $rue ii"arous re"roduction occurs where embryos $rue ii"arous re"roduction occurs where embryosreceie nourishment !rom the maternal bloodstreamreceie nourishment !rom the maternal bloodstream!rom nutritie secretions o! the mother.!rom nutritie secretions o! the mother.3


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Form and Function o&Form and Function o&

"ays"ays• >ore than /0 o!>ore than /0 o!

elasmobranchs are rays% mostelasmobranchs are rays% mosts"eciali=ed !or benthic li!e.s"eciali=ed !or benthic li!e.

• $he dorsoentrally ;attened $he dorsoentrally ;attenedbody and enlarged "ectoralbody and enlarged "ectoralfns are used as wings infns are used as wings in

swimming.swimming.• 'ater !or res"iration is ta#en in'ater !or res"iration is ta#en in

through s"iracles on to" head.through s"iracles on to" head.

• $eeth are ada"ted !or crushing $eeth are ada"ted !or crushing"rey? molluscs, crustaceans"rey? molluscs, crustaceans

and sometimes small fsh.and sometimes small fsh.• 8tingrays hae a whi"li#e tail8tingrays hae a whi"li#e tail

with s"ines and enom glands.with s"ines and enom glands.

• 1lectric rays hae large electric1lectric rays hae large electricorgans on each side o! head.organs on each side o! head.


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$u)class Holocephali$u)class Holocephali

ChimerasChimeras • >embers o! this small subclass are remnants o! a line>embers o! this small subclass are remnants o! a linethat dierged !rom the earliest shar# lineage.that dierged !rom the earliest shar# lineage.

• $here are / extant s"ecies. $here are / extant s"ecies.• Fossil chimaeras frst a""eared in the :arboni!erousFossil chimaeras frst a""eared in the :arboni!erous

and reached a =enith in the :retaceous and earlyand reached a =enith in the :retaceous and early

$ertiary, and then declined. $ertiary, and then declined.• $he mouth lac#s teeth but has large ;at "lates !or $he mouth lac#s teeth but has large ;at "lates !orcrushing !ood% the u""er -aw is !used to the cranium.crushing !ood% the u""er -aw is !used to the cranium.

• $he !ood is a wide range o! seaweed, molluscs, $he !ood is a wide range o! seaweed, molluscs,echinoderms, crustaceans and fsh.echinoderms, crustaceans and fsh.


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Osteichthyes BonyOsteichthyes Bony

FishesFishes • Cn the early to middle 8ilurian, a lineage o!Cn the early to middle 8ilurian, a lineage o!

fshes with bony endos#eletons gae rise tofshes with bony endos#eletons gae rise toa clade that contains IM o! liing fshesa clade that contains IM o! liing fshesand all liing tetra"ods.and all liing tetra"ods.

• +ther early fshes are now #nown to also+ther early fshes are now #nown to alsohae had bone.hae had bone.

• $hree !eatures unite bony fshes and $hree !eatures unite bony fshes andtetra"od descendants.tetra"od descendants.3 1ndochondral bone is "resent that re"laces1ndochondral bone is "resent that re"laces

cartilage deelo"mentally.cartilage deelo"mentally.3 A lung or swim bladder is "resent that wasA lung or swim bladder is "resent that was

eoled as an extension o! the gut.eoled as an extension o! the gut.

3 $hey hae seeral cranial and dental characters $hey hae seeral cranial and dental characters

unique to this clade.unique to this clade.


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:lassifcation:lassifcation

• +steichthyes does not defne a natural+steichthyes does not defne a naturalgrou" and is a term o! coneniencegrou" and is a term o! conenience

rather than a alid taxon.rather than a alid taxon.

• By the middle o! the 9eonian, bonyBy the middle o! the 9eonian, bonyfshes deelo"ed into two ma-orfshes deelo"ed into two ma-or

lineages.lineages.

3 $he ray2fnned fshes, class Actino"terygii, $he ray2fnned fshes, class Actino"terygii,radiated to !orm modern bony fshes.radiated to !orm modern bony fshes.

3 8een s"ecies o! lobe2fnned fshes, class8een s"ecies o! lobe2fnned fshes, class

8arco"terygii, include lungfshes and the8arco"terygii, include lungfshes and the

coelacanth.coelacanth.


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Ada"tie :haracteristicsAda"tie :haracteristics

• $he o"erculum increased res"iratory $he o"erculum increased res"iratoryeciency% outward rotation hel"edeciency% outward rotation hel"ed

draw water across the gills.draw water across the gills.• $he gas2flled structure oD the $he gas2flled structure oD the

eso"hagus hel"ed in buoyancy andeso"hagus hel"ed in buoyancy and

also in hy"oxic waters.also in hy"oxic waters.• 8"eciali=ation o! -aw musculature8"eciali=ation o! -aw musculature

im"roed !eeding.im"roed !eeding.


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Fig. 7./JFig. 7./J


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,eleosts,eleosts

• $eleosts constitute IM o! all liing fshes and hal! $eleosts constitute IM o! all liing fshes and hal!o! all ertebrates.o! all ertebrates.

•


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Class Actinopterygii "ay-!nnedClass Actinopterygii "ay-!nned

FishesFishes • +er , ** s"ecies o! ray2fnned fshes constitute the+er , ** s"ecies o! ray2fnned fshes constitute the

most !amiliar bony fshesmost !amiliar bony fshes..

Morphological ,rendsMorphological ,rends

• 4eay dermal armor re"laced by light, thin, ;exible4eay dermal armor re"laced by light, thin, ;exiblecycloid and ctenoid scales.cycloid and ctenoid scales.3 Cncreased mobility hel"s fsh aoid "redators and in !ood getting.Cncreased mobility hel"s fsh aoid "redators and in !ood getting.3 8ome eels, catfshes and others com"letely lost scales.8ome eels, catfshes and others com"letely lost scales.

• Fins changed to "roide greater mobility and sere aFins changed to "roide greater mobility and sere aariety o! !unctions? bra#ing, streamlining and socialariety o! !unctions? bra#ing, streamlining and social

communication.communication.• $he $he homocercalhomocercal tail allowed greater s"eed andtail allowed greater s"eed andbuoyancy.buoyancy.

• $he swim bladder shi!ted !rom "rimarily res"iratory to $he swim bladder shi!ted !rom "rimarily res"iratory tobuoyancy in !unction.buoyancy in !unction.

• $he -aw changed to increase suctioning and "rotrusion to $he -aw changed to increase suctioning and "rotrusion tosecure !ood.secure !ood.


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Fig. 7./Fig. 7./


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Class $arcopterygii Lo)e-!nnedClass $arcopterygii Lo)e-!nned

FishesFishes • +nly seen s"ecies are alie today% six s"ecies+nly seen s"ecies are alie today% six s"ecies

o! lungfshes and the coelacanth.o! lungfshes and the coelacanth.

• 1arly 8arco"terygians had lungs as well as gills,1arly 8arco"terygians had lungs as well as gills,and a heterocercal tail.and a heterocercal tail.

• 9uring the


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$he $he CoelacanthCoelacanth

• :oelacanths arose in the 9eonian,:oelacanths arose in the 9eonian,radiated, reached a "ea# in theradiated, reached a "ea# in the>eso=oic and dramatically declined.>eso=oic and dramatically declined.

• $hought to be extinct E* mys, a $hought to be extinct E* mys, as"ecimen was dredged u" in /I.s"ecimen was dredged u" in /I.

• 1entually more were caught oD1entually more were caught oDthe coast o! the :omoro Cslands,the coast o! the :omoro Cslands,and in /II, in Cndonesia.and in /II, in Cndonesia.

• $he liing coelacanth is a $he liing coelacanth is adescendant o! 9eonian !reshwaterdescendant o! 9eonian !reshwaterstoc#.stoc#.

• $he tail is di"hycercal with small $he tail is di"hycercal with smalllobe between the u""er and lowerlobe between the u""er and lowerlobes.lobes.

• Noung coelacanths are born !ully Noung coelacanths are born !ully!ormed a!ter hatching !rom eggs u"!ormed a!ter hatching !rom eggs u"to nine cm in diameter.to nine cm in diameter.


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Locomotion in aterLocomotion in ater

•$peed$peed 3 >ost fshes swim maximally at ten body>ost fshes swim maximally at ten body

lengths "er second% a larger fshlengths "er second% a larger fshthere!ore swims !aster.there!ore swims !aster.

3 8hort bursts o! s"eed are "ossible !or a8hort bursts o! s"eed are "ossible !or a

!ew seconds.!ew seconds.


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MechanismMechanism • $he trun# and tail musculature "ro"els a fsh. $he trun# and tail musculature "ro"els a fsh.

• >uscles are arranged in =ig=ag bands called>uscles are arranged in =ig=ag bands calledmyomeres% they hae the sha"e o! a ' onmyomeres% they hae the sha"e o! a ' on

the side o! the fsh.the side o! the fsh.

• Cnternally the bands are !olded and nested%Cnternally the bands are !olded and nested%each myomere "ulls on seeral ertebrae.each myomere "ulls on seeral ertebrae.


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>echanis>echanis

mm

• Fish undulations moe bac#wardFish undulations moe bac#wardagainst the water, "roducing aagainst the water, "roducing a

reactie !orce with two "arts.reactie !orce with two "arts.

• $he thrust "ushes the fsh $he thrust "ushes the fsh!orward and oercomes drag.!orward and oercomes drag.

• $he lateral !orce ma#es the $he lateral !orce ma#es thefshLs head “yaw”% a large andfshLs head “yaw”% a large and

rigid head minimi=es yaw.rigid head minimi=es yaw.

• $he swaying body generates too $he swaying body generates toomuch drag !or !ast s"eed.much drag !or !ast s"eed.

• Fast fsh are less ;exible andFast fsh are less ;exible andgenerate all thrust with theirgenerate all thrust with their

tails.tails.• Fast oceanic fsh hae swe"t2Fast oceanic fsh hae swe"t2

bac# sic#le2li#e tail fns, similarbac# sic#le2li#e tail fns, similar

to high2as"ect ratio wings o!to high2as"ect ratio wings o!

birds.birds.


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*conomy*conomy

• 8wimming is the most economical !orm o! motion8wimming is the most economical !orm o! motionbecause water buoys the animal.because water buoys the animal.

• $he energy cost "er #ilogram o! body weight !or $he energy cost "er #ilogram o! body weight !ortraeling one #ilometer is *.I Ocal !or swimming,traeling one #ilometer is *.I Ocal !or swimming,

/.7J Ocal !or ;ying and J.7 !or wal#ing./.7J Ocal !or ;ying and J.7 !or wal#ing.• Ct is yet to be determined how aquatic animals canCt is yet to be determined how aquatic animals canmoe through water with little turbulence.moe through water with little turbulence.

/ t l B d th $ i/ t l B d th $ i


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/eutral Buoyancy and the $wim/eutral Buoyancy and the $wim

BladderBladder• Fish are slightly heaier thanFish are slightly heaier than

water.water.• $o #ee" !rom sin#ing, shar#s must $o #ee" !rom sin#ing, shar#s must

continually moe !orwardcontinually moe !orward

• $he shar# lier has $he shar# lier has s0ualines0ualine, a, a!atty hydrocarbon, that acts to!atty hydrocarbon, that acts to#ee" shar#s a little buoyant.#ee" shar#s a little buoyant.

• $he $he swim )ladderswim )ladder, is the most, is the mostecient ;otation deice.ecient ;otation deice.3 A fsh can control de"th by ad-ustingA fsh can control de"th by ad-usting

the olume o! gas in the swim bladder.the olume o! gas in the swim bladder.

3 9ue to "ressure, as a fsh descends,9ue to "ressure, as a fsh descends,the bladder is com"ressed ma#ing thethe bladder is com"ressed ma#ing thetotal density o! the fsh greater.total density o! the fsh greater.

3 As a fsh ascends, the bladder ex"andsAs a fsh ascends, the bladder ex"andsma#ing the fsh lighter and it will risema#ing the fsh lighter and it will riseeer !aster.eer !aster.


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"espiration"espiration

• Fish gills are flaments with thinFish gills are flaments with thine"idermal membranes !olded intoe"idermal membranes !olded into

"late2li#e lamellae."late2li#e lamellae.

• $he gills are inside the "haryngeal $he gills are inside the "haryngealcaity and coered with a moablecaity and coered with a moable

;a", the o"erculum.;a", the o"erculum.

• $he o"erculum "rotects the delicate $he o"erculum "rotects the delicategill flaments and streamlines the body.gill flaments and streamlines the body.

•


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6es"iration6es"iration

• Although it a""ears "ulsatile, water ;owAlthough it a""ears "ulsatile, water ;owoer gills is continuous.oer gills is continuous.

• 'ater ;ow is o""osite to the blood ;ow% this'ater ;ow is o""osite to the blood ;ow% thiscountercurrent exchange maximi=escountercurrent exchange maximi=es

exchange o! gases.exchange o! gases.• 8ome bony fshes remoe JM o! the oxygen8ome bony fshes remoe JM o! the oxygen!rom water that "asses oer their gills.!rom water that "asses oer their gills.

• 8ome actie fshes use8ome actie fshes use ram ventilationram ventilation%%

!orward moement is sucient to !orce!orward moement is sucient to !orcewater across gills.water across gills.

• 8uch fshes are as"hyxiated in a restrictie8uch fshes are as"hyxiated in a restrictieaquarium een i! the water is saturated withaquarium een i! the water is saturated withoxygen.oxygen.


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Fig. 7.Fig. 7.


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Fishes Out o& aterFishes Out o& ater

• @ungs o! lungfshes allow them to res"ire !rom@ungs o! lungfshes allow them to res"ire !romair.air.

• 1els can wriggle oer land during rainy weather%1els can wriggle oer land during rainy weather%they use s#in as their ma-or res"iratory sur!ace.they use s#in as their ma-or res"iratory sur!ace.

• A bowfn uses gills at cooler tem"eratures and itsA bowfn uses gills at cooler tem"eratures and itslung2li#e swim bladder at higher tem"eratures.lung2li#e swim bladder at higher tem"eratures.

• $he electric eel has degenerate gills and gul"s air $he electric eel has degenerate gills and gul"s airthrough its ascular mouth caity.through its ascular mouth caity.

• $he Cndian climbing "erch s"ends most o! its time $he Cndian climbing "erch s"ends most o! its timeon land, breathing air in s"ecial chambers.on land, breathing air in s"ecial chambers.


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Osmotic "egulationOsmotic "egulation

• Freshwater has !ar less salt than is inFreshwater has !ar less salt than is infsh blood% water tends to enter thefsh blood% water tends to enter the

body o! the fsh and salt is lost bybody o! the fsh and salt is lost by

diDusion.diDusion.• $he scaled and mucous2coered body $he scaled and mucous2coered body

is mostly im"ermeable, but gills allowis mostly im"ermeable, but gills allow

water and salt ;uxes.water and salt ;uxes.


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Freshwater !shes areFreshwater !shes are

hyperosmotic regulatorshyperosmotic regulators..

• $he o"isthone"hric #idney "um"s excess $he o"isthone"hric #idney "um"s excesswater out.water out.

• 8"ecial salt2absorbing cells located in8"ecial salt2absorbing cells located in

e"ithelium actiely moe salt ions !rom thee"ithelium actiely moe salt ions !rom thewater to the fshesL blood.water to the fshesL blood.

• c$hese systems are ecient% a !reshwater fshc$hese systems are ecient% a !reshwater fshdeotes little energy to #ee"ing osmoticdeotes little energy to #ee"ing osmotic

balance.balance.• About I*M o! bony fshes are restricted toAbout I*M o! bony fshes are restricted to

either !reshwater or seawater habitats.either !reshwater or seawater habitats.

• 1uryhaline fshes lie in estuaries where salinity1uryhaline fshes lie in estuaries where salinity

;uctuates throughout the day.;uctuates throughout the day.


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Marine )ony !shes areMarine )ony !shes are

hypoosmotic regulatorshypoosmotic regulators..

• >arine fshes hae a much lower blood salt>arine fshes hae a much lower blood saltconcentration than in the seawater around them.concentration than in the seawater around them.

• $here!ore they tend to lose water and gain salt% the $here!ore they tend to lose water and gain salt% themarine fsh ris#s “drying out.”marine fsh ris#s “drying out.”

• $o com"ensate !or water loss, a marine teleost $o com"ensate !or water loss, a marine teleostdrin#s seawater% this brings in more unneeded salt.drin#s seawater% this brings in more unneeded salt.

• Gnneeded salt is carried by the blood to the gillsGnneeded salt is carried by the blood to the gillsand secreted by s"ecial salt2secretory cells.and secreted by s"ecial salt2secretory cells.

• 9ialent ions o! magnesium, sul!ate and calcium9ialent ions o! magnesium, sul!ate and calciumare le!t in the intestine and leae the body with theare le!t in the intestine and leae the body with the!eces or enter the bloodstream and are excreted!eces or enter the bloodstream and are excretedby the #idney.by the #idney.

• >arine fsh excrete dialent ions by tubular>arine fsh excrete dialent ions by tubularsecretion% glomeruli are small or missing.secretion% glomeruli are small or missing.


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Fig. 7.IFig. 7.I


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Feeding BehaviorFeeding Behavior

• Fish deote most o! their time searching !orFish deote most o! their time searching !or!ood to eat and eating.!ood to eat and eating.

• 'ith the eolution o! -aws, fsh le!t a "assie'ith the eolution o! -aws, fsh le!t a "assieflter2!eeding li!e and entered a "redator2"reyflter2!eeding li!e and entered a "redator2"rey

battle.battle.• >ost fsh are>ost fsh are carnivorescarnivores that !eed onthat !eed on

=oo"lan#ton, insect larae and other aquatic=oo"lan#ton, insect larae and other aquaticanimals.animals.

• >ost fsh do not chew !ood since it would>ost fsh do not chew !ood since it wouldbloc# water ;ow across the gills.bloc# water ;ow across the gills.3 >ost swallow !ood whole% this is easy with water>ost swallow !ood whole% this is easy with water

"ressure that swee"s !ood in when the mouth"ressure that swee"s !ood in when the mouth

o"ens.o"ens.


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Feeding BehaiorFeeding Behaior

• 8ome fsh are8ome fsh are her)ivoresher)ivores and eat "lants andand eat "lants andalgae% they are crucial intermediates in thealgae% they are crucial intermediates in the!ood chain.!ood chain.

• $uspension &eeders$uspension &eeders are a third grou", andare a third grou", andcro" the abundant microorganisms o! the sea.cro" the abundant microorganisms o! the sea.• >any o! the "lan#ton !eeders swim in large>any o! the "lan#ton !eeders swim in large

schools and use the gill ra#ers to strain !ood.schools and use the gill ra#ers to strain !ood.

• OmnivoresOmnivores can !eed on both "lant andcan !eed on both "lant andanimal !ood.animal !ood.

• $cavengers$cavengers !eed on organic debris.!eed on organic debris.• 1arasitic1arasitic fshes suc# the body ;uids o! otherfshes suc# the body ;uids o! other

fshes.fshes.


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"eproduction"eproduction

• >ost fshes are dioecious with external>ost fshes are dioecious with external!ertili=ation and external deelo"ment.!ertili=ation and external deelo"ment.

• Hu""ies and mollies re"resent ooii"arous fshHu""ies and mollies re"resent ooii"arous fsh

that deelo" in the oarian caity.that deelo" in the oarian caity.• 8ome shar#s are ii"arous with some #ind o!8ome shar#s are ii"arous with some #ind o!

"lacental attachment to nourish young."lacental attachment to nourish young.

• >ost oi"arous "elagic fsh lay huge numbers o!>ost oi"arous "elagic fsh lay huge numbers o!eggs% a !emale cod may release 72 million eggs.eggs% a !emale cod may release 72 million eggs.

• ear2shore and bottom2dwelling s"ecies lay larger,ear2shore and bottom2dwelling s"ecies lay larger,ty"ically yol#y, nonbuoyant and adhesie eggs.ty"ically yol#y, nonbuoyant and adhesie eggs.

• 8ome bury eggs. >any attach them to egetation8ome bury eggs. >any attach them to egetationand some incubate them in their mouths.and some incubate them in their mouths.


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6e"roduction6e"roduction

• >any benthic s"awners guard their>any benthic s"awners guard theireggs% usually the male is the guard.eggs% usually the male is the guard.

• Freshwater fshes "roduceFreshwater fshes "roducenonbuoyant eggs% the more carenonbuoyant eggs% the more care

"roided, the !ewer the eggs"roided, the !ewer the eggs

"roduced."roduced.• Freshwater fshes may hae elaborateFreshwater fshes may hae elaborate

mating dances be!ore s"awning.mating dances be!ore s"awning.

9eelo"me9eelo"me


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9eelo"me9eelo"me

ntnt• $he fsh hatches carrying a $he fsh hatches carrying asemitrans"arent yol# sac tosemitrans"arent yol# sac to

su""ly !ood until it can !orage.su""ly !ood until it can !orage.• $he change !rom lara to $he change !rom lara to

adult may be dramatic inadult may be dramatic in

body sha"e, fns, colorbody sha"e, fns, color

"atterns, etc."atterns, etc.

• Hrowth is tem"eratureHrowth is tem"eraturede"endent% warmer fsh growde"endent% warmer fsh grow

more ra"idly.more ra"idly.

• Annual rings on scales,Annual rings on scales,

otoliths, etc. re;ect seasonalotoliths, etc. re;ect seasonalgrowth cycles.growth cycles.

• >ost fsh continue to grow>ost fsh continue to growthroughout li!e and do notthroughout li!e and do not

sto" at maturity.sto" at maturity.


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$he 1nd.

Documents

Chapt24 Fishes