Questions from week one?
• Lecture one: see white perch gonads
• Lecture two: White perch - opportunistic
feeders
• Lecture one: Lateral line
Red vs white muscle
• Red (aerobic)
– High capillary density
– Appears red due to O2 binding pigments
myoglobin and hemoglobin
– Allows adequate oxygenation on muscle
– Metabolizes lipids in mitochondria
• White (anaerobic)
– Converts glycogen to lactate
– Increases pH
Evolution and Ecology
Fishes of Wisconsin
Goal:
an overview of phylogeny and
functional morphology in the
context of ecology
– When traits evolved
• The characteristics of main groups
– Functional morphology
• Background to understand how traits affect
ecology
Evolution basics and
terminology
• Natural Selection
• Ecological niche
– Position in an ecosystem; how an organism
makes a “living”
• Adaptive Radiation
– Divergent evolution to fill ecological niches
driven by natural selection (cichlids)
• Functional Morphology
– Relationship between form and function
Taxonomic Nomenclature
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Kingdom – Animalia
Phylum – Craniata
Class – several
Order – in fishes, always ends with -iformes
Family – in fishes, always ends with -idae
Genus – complex nomenclatural conventions
Species – complex nomenclatural conventions
Cladograms
Agnatha
Chondrichthyes
Sarcopterygii
Actinopterygii
Osteichthyes
Bony fish
Gnathostomata
Jaws
Jawless Fishes
Superclass: Agnatha
Agnatha
Chondrichthyes
Sarcopterygii
Actinopterygii
Osteichthyes
Bony fish
Gnathostomata
Jaws
Jawless Fishes
Superclass: Agnatha
• Absence of jaw (agnathous)
• Absence of paired fins
• Presence of notochord
Jawless Fishes
Hagfishes (Order: Myxiniformes)
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Notochord (no vertebrae)
Exclusively marine
30-35 species
Harvested commercially
– “eel-skin” leather
• Knots
Jawless Fishes
Lampreys (Order: Petromyzontiformes)
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Vertebrae
Oral disk - grasp prey and create hole
Dorsal and caudal fins
Lateral line system
Well-developed eyes
~ 40 species
Jawed Fishes
Superclass: Gnathostomata
Agnatha
Chondrichthyes
Sarcopterygii
Actinopterygii
Osteichthyes
Bony fish
Gnathostomata
Jaws
Jawed Fishes
Superclass: Gnathostomata
Composed of:
– Cartilaginous fishes (Class: Chondricthyes)
– Lobe-finned fishes (Class: Sarcopterygii)
– Ray-finned fishes (Class: Actinopterygii)
longnose gar (Lepisosteus osseus)
Jawed Fishes
Class: Chondrichthyes
Agnatha
Chondrichthyes
Sarcopterygii
Actinopterygii
Osteichthyes
Bony fish
Gnathostomata
Jaws
Class: Chondrichthyes
Cartilaginous fishes
• Sharks, rays, skates
and chimaeras
• 850 extant species
• Cartilaginous skeleton
• Jaw teeth in rows
• Placoid scales (most)
Jawed Fishes
Class: Osteichthyes
Agnatha
Chondrichthyes
Sarcopterygii
Actinopterygii
Osteichthyes
Bony fish
Gnathostomata
Jaws
Class: Osteichthyes
• Diverse class
The bony fishes
– Subclass Sarcopterygii
– Subclass Actinopterygii
• Lungs or swimbladder
• Bony skeleton
– Some ossification
Sublass: Sarcopterygii
Lobed-finned fishes
• Characterized by fleshy fins with
bony, leg-like supports
Lemur
– Coelacanths (Infraclass: Actinistia)
– Lungfishes (Infraclass: Dipnoi)
– Tetrapods
Latimeria
Neoceratodus
Sublass: Actinopterygii
Ray-finned fishes
• Dominant fishes on the planet
– Approx. 24,000 species
• Possess fin rays
Sarcopterygii vs Actinopterygii
Pectoral fin
Coelocanth
Teleost
Relict Actinopterygians
• Infraclass Chondrostei
– mostly cartilaginous with some bone
– Sturgeons, paddlefish, bichirs and reed fish
• Infraclass Neopterygii (“new wing”)
– Gars and bowfin
bowfin (Amia calva)
lake sturgeon (Acipenser fulvescens)
bichir (Polyterus spp.)
Actinopterygians continued:
Teleostei - the main line of fish evolution
• Compose ~95% of all extant species
(~23,680)
• Characterized by
– cycloid or ctenoid scales
– increased cranial complexity
– swim bladders (usually)
Major Trends in Fish Evolution
• Changes in cranium and jaw structure
– Branchiostegal rays
– Pre-maxilla separation
• Changes in movement
– Loss of external armor
– Fins
– Air bladders
Branchiostegal Rays
• Maintains a flexible seal between operculum
and body as oral cavity expands
– Allows for active pumping of water across
gills
– Allows for feeding methods based on
suction
Jaw Structure
“Primitive”
PM
MX
MX
PM
“Derived”
Jaw Structure cont…
Brook trout – primitive,
maxilla included in gape
Largemouth bass – derived,
maxilla excluded from gape
• Scales
Loss of external armor
– Reduction in heaviness,
increase in flexibility
– Note:
• surviving Chonrosteians
have no scales over most of
their bodies
• many teleost have
eliminated scales
Spines
• Spine development followed loss of
external armor
– Anti-predator device
Movement of Pelvic Fins From
Abdominal to Thoracic Position
“Primitive”
“Derived”
Abdominal
Position
• Anterior shift associated with increased
maneuverability
Thoracic
Position
– Pelvic fins help control movement rather than
just stabilize
Caudal Fin Evolution
• Heterocercal
– Provide lift
• Homocercal
– Improved thrust
– Closely related to
development of
neutral buoyancy
Swimbladder
• Lungs evolved before swim bladders
• Swimbladder
– Trend of importance
•  in respiration
•  in buoyancy
Basic Body Types
• Fusiform
• Laterally compressed (Deep-Bodied)
• Dorso-ventrally compressed (Flat-fish)
• Cylindrical/Attenuated
Fusiform Body Type
“classic” fish shape
Brown
Trout
Largemouth
Bass
Pike
Fathead
Minnow
Laterally Compressed/Deep Bodied
Body Type
(Acrobatics and Maneuvering)
Bluegill Sunfish
Butterfly Fish
Dorso-ventrally Compressed Body Type
(Bottom Dwellers)
California Halibut
Flathead Catfish
Mottled
Sculpin
Lake Sturgeon
Cylindrical/Attenuated Body type
(Hiders/Burrowers)
American Eel
Hagfish
Basic Mouth Types
Superior
Terminal
Sub-Terminal
Inferior
Mouth Shapes
• O - shaped (maximum area to perimeter)
– Creates a vacuum in the water
– expanding pre-maxila outward
– Found commonly in Planktivores
• V-Shape or Duck Bill Shape
– Vacuum less directed and less powerful
– Allows for prey capture from the side
– Found commonly in large Piscivores
Largemouth Bass Jaw Protrusion
Decreases distance between predator and prey
Increases the amount of suction force generated
PM
PM
MX
MX
Extreme Jaw Protrusion!
Mouth Size
• Mouth Size matches prey size.
Putting it together with
Fin Placement
Rover-Predators
Fusiform, Streamlined body
Forked Tail,
Narrow or Average
Peduncle
Terminal
mouth
-Fins more or less evenly distributed for stability and
manuverability
-Constantly moving and searching for prey
Lie and Wait predators
Acceleration Specialists
Flexible, Torpedo-Like Body
Thick Caudal
Peduncle
Large Gape
Ventrally-placed Pectoral Fin
Small Pectoral and
Pelvic fins relative to
body size
Posterior-placed Median
Fins (Dorsal and Anal)
Maneuvering Specialists –
Adaptations for Suction Feeding
Spines for Defense
Laterally Compressed Body
Large Fins
Relative To
Body Size
Small
protrusible
mouth
Fins Evenly
Distributed
Spines for Defense
Laterally Positioned Pectoral Fins
Bottom Rovers
Humped Back
Enlarged Pectoral Fins
Subterminal or
Inferior Mouth
Flattened Head
Barbels
Bottom Clingers
Flattened Head
and Body
Modified, Closely
Spaced Pelvic
Fins
Enlarged Pectoral Fin