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98 Cards in this Set

  • Front
  • Back

What is a fish?

1) aquatic

2) vertebrates (except hagfish, lampreys)

3) cold blooded = poikilotherms

4) median and paired fins

5) scales

6) gills

7) one way heart with two chambers

8) lateral line

evolutionary trends

1) a shift in position of paired fins

2) and increase in overall spininess

3) changes in body shape (primitive = fusiform, derived = shorter, fatter, lower vertebral counts)

What caused changes in fish?

when Pangaea started to break apart, there was a huge increase in the amount and type of marine space available --> different body types being useful in different environments

Characteristics of Phylum Chordata

1) notochord

2) dorsal hollow nerve chord

3) pharyngeal gill slits

What did fish evolve from?

probably from invertebrate chordate ancestors (lancelets and tunicates)


retention of larval features into the adult stage

Infraphylum Vertebrata characteristics

1) most have bony skeleton

2) vertebral column

3) distinct cranium, skull with a brain

Superclass Agnatha (jawless fishes)

Ostracoderms (shell skinned)

- first fossils = marine origin

- no internal bone

- muscular feeding pump

- heavy body armor

- not true fins with bony support

- cartilaginous skeleton

- marine and freshwater

Hagfish characteristics


- slime!

- scavengers

- ties in knots to feed

- only marine, no osmoregulation

Lamprey characteristics


- oral disk in adults with horny teeth on tongue

- freshwater or migratory (and parasitic)

Characteristics of both lampreys and hagfish

- lack jaws

- lack bone, cartilaginous skeleton

- lack paired fins

- single median nostril

- lack true gill arches

- single gonad

- lack body armor

Evolution of jaws

evolved from gill arches

allowed for:

- manipulation of food and objects

- greater diet options

- defense

Superclass Gnathostomata

Jawed fishes

- Class Placodermi

- Class Acanrhodii

- Class Sarcopterygii

- Class Chondrichtyhs

- Class Actinopterygii

Class Placodermi = plate skinned (extinct)

- first marine, then freshwater

- jaws but cant create suction

- no teeth replacement

- paired fins

- internal skeleton

- mostly benthic

Class Acanthodii = spiny sharks (extinct)

- cartilaginous skeleton

- large head and large eyes

- subterminal mouth

- pelagic

- affinity with modern fishes

Class Chondrichthyes = sharks, skates, rays

Subclass Elasmobranchii

Subclass Holocephali

Evolution of Elasmobranchs

1st radiation = cladoselachid sharks, terminal mouth, homocercal caudal fin, notochord support

2nd radiation = hybodonts, anal fin, heterocercal caudal fin, notochord with neural arches

3rd radiation = modern sharks, protrusible upper jaw, dentition replacement, ceratotrichia supporting fins, calcified vertebrae

Features of modern elasmobranchs

1) cartilaginous skeleton

2) 5 gill slits, no operculum

3) spiracle to take in water

4) paired ventral nostrils

5) subterminal mouth

6) jaw suspension = hyostylic (jaws not directly connected to brain case)

7) ceratotrichia

8) placoid scales

9) enlarged liver for bouyancy

10) spiral valve intestine

11) ampullae of lorenzini

12) single cloaca

13) internal fertilization, males have claspers

life history patterns of elasmobranchs

1) distribution = mostly marine

2) adapted for movement at low energy costs (heterocercal tail, placoid scales, cartilage, squalene)

3) feeding = mostly predators

4) reproduction = internal fertilization (ovi/ovovivi/vivi)

5) good non visual senses

6) low fecundity, slow growing, long lived

Elasmobranchii - Subdivision Batoidea

- ventral gill openings

- enlarged pectorals attached to side of head

- no anal fin

- eyes and spiracles on top of head

- pavement like teeth

- bottom feeders

Subclass Holocephali

Share with sharks:

- cartilaginous skeleton

- male intermittent organs

- squalene filled livers

- ceratotrichia

Different than sharks

- holostylic jaw suspension = jaw directly connected to cranium

- single external gill slit with operculum

- all are oviparous

- seperate anal and urogenital openings

- no scales

Superclass Gnathostomata - Grade Teleostomi

Class Acanthodii (extinct)

Subgrade Euteleostomi = bony fishes

- Class Sarcopterygii

- Class Actinopterygii

Subgrade Euteleostomi

- jawed

- true bony skeletons

- bony operculum covering gill arches

- 3 semicircular canals, 3 otolithis

- paired fins

- swim bladders

- lepidotrichia

Class Sarcopterygii = lobed fins

- marine and freshwater

- lobed = series of bony elements link fins to pelvic and pectoral girdles (like tetrapods)

- jaw suspension is holostylic

- cosmine = complex tissue that covers scales

Class Sarcopterygii - Subclass Coelacanthimorpha

- three lobed tail = diphycercal

- large swim bladder filled with fat

- bottom oriented nocturnal predators

- disappeared from record 65mya but found again recently

Class Sarcopterygii - Subclass Dipnoi (double breather lung fish)

- all living now freshwater

- functional lungs

- massive tooth plates (teeth attached to interior bones)

- estivation = reduced metabolism during dry out

- intermediate heart

Class Actinopterygii = ray fins

- fins attached to body via fin rays

- branchiostegal rays

- distinct pelvic and pectoral girdles

- bony skeleton

Class Actinopterygii - Subclass Cladista

- spiracles but used for exhaling from the lungs

- lobe like fins (like sarcopterygians)

- ganoid scales (like gars)

- two gular plates (like coelancath)

- external gills when young, two lobed lungs

- fins different from any other group

Class Actinopterygii - Subclass Chondrostei

- cartilaginous skeleton

- heterocercal tail

- spiral valve intestine

- heavy ganoid scales

- spiracles

- one branchiostegal

Class Actinopterygii - Subclass Neopterygii

- intermediate between chondrosteans and teleosts

Lepisosteiformes (gars) and Amiiformes (bowfin) both have:

- heterocercal tail

- spiral valve intestine

- ossified skeleton

- functional lungs

Subclass Neopterygii - Lepisosteiformes (gar)

- ambush predators

- primarily freshwater

- toxic eggs

- can breathe air

Subclass Neopterygii - Amiiformes (bowfin)

- bony head

- can swim by undulations of dorsal fin

- air breathers

Subclass Neopterygii - Division Teleosti

1) operculum has 4 bones

2) homocercal tail supported by uroneurals, hypurals and epurals

3) cycloid/ctenoid scales

4) ossified, lightweight vertebrae

5) swimbladder provides bouyancy

6) premaxilla is principle bone of upper jaw

7) fins with rays and spines

8) body shape is extensive

Teleosts radiated due to improvements in:

1) swimming abilities

- replacement of heavy armor with scales

- swim bladder

- homocercal tail

2) feeding mechanisms

- upper jaw mobility

Division Teleosti - Subdivision Osteoglossomorpha (bony tongues)

- most teeth on tongue or roof of mouth

- huge scales

- freshwater, tropical

- some are electric

Division Teleosti - Subdivision Elopomorpha

- leptocephalous larvae

- snake like bodies

Division Teleosti - Subdivision Otocephala - Superorder Clupeomorpha

- open water = silvery compressed bodies

- planktivorous

- otophysic connection for swimbladder (touches inner ear)

- mostly marine

Division Teleosti - Subdivision Otocephala - Superorder Ostariophysi

- Schreckstoff = chemical alarm substance

- Weberian apparatus = series of bones connect swimbladder to inner ear, increases low frequency hearing

- 64% of all freshwater fishes

Division Teleosti - Subdivision Euteleosti

10 superorders

Subdivision Euteleosti - Superorder Neognathi

- pikes

- freshwater

- ambush predators

- median fins sit back to increase surface area for propulsion

Subdivision Euteleosti - Superorder Protacanthopterygii (salmon and smelts)

- most have adipose fins

- hypural plates consolidated to the urostyle, strong swimmers

- slender predatory fish

- cycloid scales

- physostomous connection

- P1 and P2 usually in ancestral position

Subdivision Euteleosti - Superorder Stenopterygii

- deep sea

- photophores

- long teeth

- cyclothone = most abundant fish in world

Subdivision Euteleosti - Superorder Ateleopodomorpha (jelly noses)

- skeleton largely cartilaginous

- deep water, near the bottom

- bulbous headed

Subdivision Euteleosti - Superorder Cyclosquamata (cycloid scaled)

- almost entirely deep sea

- telescope fish with tubular eyes

- first signs of hermaphroditism

Subdivision Euteleosti - Superorder Scopelmorpha

- Diurnal migration

- make up a large fraction of deep scattering layer

- many photophores

Subdivision Euteleosti -Group Acanthomorpha (spiny teleosts)

- true spines occur in the dorsal, anal and pelvic fins

- strengthening of vertebral parts, better muscle attachment, improves locomotion

- pharyngeal teeth diversify in function

- maxilla becomes a pivot/lever for premaxilla

- 4 superorders

Subdivision Euteleosti - Superorder Lampridiomorpha

- large and pelagic fishes

- pelagic large oval predators

- strange jaw protrusion

Subdivision Euteleosti - Superorder Polymixiomorpha

- large eyes with chin barbels

- caught committing suicide

Subdivision Euteleosti - Superorder Paracanthopterygii

- reduced number of caudal and pelvic fin rays

- primarily benthic associated

- many have muscles on gas bladder to produce sound

Subdivision Euteleosti - Superorder Acanthopterygii (spiny rayed fishes)

- upper jaw mobility is maximal because of ascending process on premaxilla

- pharyngeal dentition is at highest level of developement and pharyngeal jaws moved by retractor-dorsalis muscle

Subdivision Euteleosti - Superorder Acanthopterygii - Series Mugliomorpha

- mullets

- nearshore

- caradromous = migratory

- detritivores

Subdivision Euteleosti - Superorder Acanthopterygii - Series Atherinomorpha

- most are surface feeders

- unique jaw protrusion = rostral cartilage between maxilla and premaxilla

- grunions, topsmelts, silversides

Subdivision Euteleosti - Superorder Acanthopterygii - Series Percomorpha

- pelvic girdle and pectoral girdle connected

- ctenoid scales common

Subdivision Euteleosti - Superorder Acanthopterygii - Series Percomorpha - Order Perciformes

- biggest vertebrate order

- represented primarily in tropical lakes and coral reefs

- coral reefs = gobies, wrasses, sea basses, blennies, damselfish, cardinal fish


spawn once


spawn multiple times (most common)


internal fertilization but no paternal nourishment

advantage = young are large and more advanced

disadvantage = low offspring dispersal, fewer offspring produced, if mother dies while pregnant so will offspring


viviparity and ovoviviparity

- males have an intromitten organ

1) modifications of pelvic or anal fins:

- claspers or gonopodia

2) genital papilla = non bony tube


external fertilization = most common, gametes shed into water

internal fertilization = eggs fertilized internally but later released into water (less common)

modes of ovoparity and spawning site preparation

1) broadcast spawning

2) demersel, no parent care

3) demersel, guarding

4) brooders

broadcast spawning

- most marine fishes

- eggs and sperm shed in water column and drift away

- bipartite life style = larval and adult habitat completely different

- spawning sites often maximize transport of larvae away from reef

- advantages = zero energy expenditure, long distance dispersal

- disadvantages = low survival of offspring

demersel eggs (no parent care)

- eggs may or may not be hidden

- eggs usually glued on bottom

- common in freshwater fishes

- advantages = zero energy expenditure after gametes released, may be better protected, can control where offspring end up

- disadvantages = low chance of offspring survival, lower dispersal, nest sites can become limited

demersel eggs (with parent care)

- common among reef fishes

- males usually guard

- advantages = increased offspring survival

- disadvantages = high cost to parents, increased risk to parents, nest sites may be limited


young can be brooded in mouths, on body, pouches

- offspring usually well developed when released

- advantages = increased survival, no need to find or maintain a nest

- disadvantages = high cost to parents, if parent dies so does offspring, low dispersal

parental care

- no parental care = most common

- male parental care = more common than females because of external fertilization (can accommodate multiple broods, attracts more females, paternity assurance, last to be left with eggs)

- female parental care associated with internal fertilization

- biparental care = uncommon


difference between egg and sperm sizes

- females = maximize resource intake, convert this to eggs

- males = maximize matings, high potential mating success


one sexual tissue type per individual


multiple females for one male (often serial)


multiple males for one female (often simultaneous -> group spawning)


an individual has both ovarian and testicular tissue in a lifetime

- simultaneous = both gonadal tissues function in one individual (advantages = mate with whomever you meet, can nearly double reproductive output, but rare because of male cheating)

- sequential = a switch from one gonadal tissue to another (protogynous = female first, protandrous = male first)

size advantage

1) no size advantage and gonochorism = long term monogamy or mass spawnings in large groups

2) male size advantage and protogyny = large male mate monopolization

3) female size advantage and protandry = monogamy with replacement, random pairing

size advantage model

- be the sex that has the better size advantage

- if you are a small male, its just better to be a female because then there is more of a chance of mating

size advantage model details

indeterminate growth = increased size means increased fecundity

- anisogamy = females limited by resources, males limited by matings

- protandry = territory size limits mating group to just 2 individuals, largest should be female

- protogyny = large males can defend a territory containing multiple females


parthenogenesis = females produce only females, no males needed

- gynogenetic = no male contribution, only egg activation

- hybridogenetic = male contribution is expressed, then male genes discarded each generation

secondary sexual characteristics

traits not associated with fertilization or parental care

- restricted to one sex, usually male

- do not appear until maturation

- can develop during breeding, then regress

- generally do not enhance survival

sexual dimorphism

permanently = adults have permanent distinguishable characteristics

seasonally = change color during spawning


polymorphic = one or the other sex has more than one type

monomorphic = no obvious or distinguishable different between the sexes

diadromous reproduction

anadromous = live in salt water, reproduce in freshwater (common in temperate latitudes, temperate has more productive oceans)

catadromous = live in freshwater, reproduce in saltwater (more common in tropical latitudes, tropical has more productive freshwater)

terminal vs initial phase male

initial phase male = smaller, looks still like female (will devote more energy to making more sperm and bigger gonads, participates in group mating and sneaking)

terminal phase male = larger, participates in pair pating


in the egg:

- fertilization through the micropyle

- chorion stiffens

- standard vertebrate cleavage


- softening of chorion

- duration varies (depends on temp)

critical period hypothesis

larva's ability to survive depends on its ability to feed right after it hatches


- olfactory receptors arranged on lamellae in rosettes to increase surface area (sensory nerves connect to receptors)

- fish have a great sensitivity to low concentrations of odors

functions of olfaction

1) find food

2) recognize sex pheromones

3) recognize young

4) homing behavior (diadromous)

5) defense against predation


- receptors = taste buds on and around mouth

- taste buds innervated by vagus nerves (internal) and facial nerves (on the skin)

- nerves go to medulla oblongata in the brain


- pineal organ = important for setting circadian rhythm through light perception

- main receptor = eye system of cornea, lens, iris and retina (iris controls amount of light in sharks)

- order light enters eye = pupil, lens, nerve laters, rods/cones

teleost regulation of light

(cant change size of pupil)

1) swimming towards or away from illumination

2) pigment in cornea to filter some wavelengths of light

3) light and dark adaptations by movement of pigment cells (rods/cones)

light/dark adaptations of teleosts

in dim light

- cones long

- masking pigments retracted

- rods short (to be closer to external membrane)

in bright light

- cones short

- making pigments advance to protect rods

- rods long

takes about 20-30 minutes for light adaptation and 1 hour for dark adaptation

cones vs rods

- rods = one neural fiber for many rods, for definition of brightness

- cones = for color/hue definition, each cone has different visual pigment

tapetum lucidum

important for elasmobranchs and nocturnal species

- reflecting layer to increase visual sensitivity by shining light back through the retina

- composed of layer of guanine crystals

absorption spectrum

blue penetrates deeper than red

vision uses

1) feeding

2) reproduction

3) predator avoidance

4) schooling

mechanoreception (acoustico lateralis system)

- sound vibration/water motion causes fish to move, otolith or endolymph lags, some hair cells are bent, transmission of electrical nerve impulses to the brain

- neuromast organs = hair cells grouped together (found in lateral line, ampullae, otolith sacs)

- cupula increases sensitivity to hair cells to detect a stimulus

how does hearing work

pars inferior (2 sacs with otoliths)

good for low frequency, high energy

how does balance work

pars superior (1 sac with otolith, 3 semi circular canals each with an ampulla)

swimbladder functions

- acts as an amplifier to produce more sound and energy

functions of hearing

1) important if vision isn't an option

2) reproduction

3) predator avoidance

4) prey detection

5) territorial defense

6) alarm sounds

lateral line system

- receptors are neuromasts

- cupula responds same way as balance

- important for orientation, spatial equilibrium