Today’s outline
 Introductions
 Review syllabus
 Expectations and goals
 Lecture – Fish Anatomy
 Lab – fish dissections
Bluegill
Walleye
Diversity of fishes
“Take this fish and look at it.”
What do you think:
What is a fish?
What could we learn from inspecting
and dissecting a fish? (Think about
what you learned already…)
What is a Fish?
 Poikilothermic – body temperature is identical to surrounding




water
Chordates – have developmental characteristics of all
vertebrates
Appendages developed as fins
Chief respiratory organs are gills
Body generally covered with scales
“A fish is an aquatic vertebrate with gills and with limbs in the shape of
fins” (Nelson 1994)
There are >30,000 fish species, so there are exceptions to these
general characteristics.
Fish anatomy
 Forms the basis for most identification
 Anatomy can teach us about ecology & evolutionary
relationships
Mississippi paddlefish
Porcupinefish
Ocean sunfish
Leafy seadragon
Why dissect fish?
 Evolution / phylogeny
 Physiology
 Pathology/disease
 Gut contents
 Otoliths (aging)
 Fecundity/fitness
Today’s Fish Goals
 Practice skills of close observation
 Learn basic external and internal anatomy of fishes
 Practice using a dichotomous key to ID fish
 Begin thinking about how structure relates to function
Muskellunge
Flounder
Anatomical terminology
Dorsal
Anterior
Posterior or
caudal
Lateral
Ventral
Used for relating different parts….Eye is posterior to the mouth
Conversely the mouth is anterior to the eye
Lateral
External Anatomy
Fins
Sail fish
(Istiophorus platypterus)
American eel
(Anguilla rostrata)
Mouth
White sucker
(Catostomus commersonii)
River hatchetfish
(Gasteropelecus sternicla )
Scales
Longnose gar
(Lepisosteus osseus)
Great white shark
(Carcharodon carcharias)
Fins
Dorsal
Caudal
Pectoral
Anal
Pelvic
Adipose
Anal
Pelvic
Pectoral
Caudal Fins
Heterocercal
Protocercal
•
Tip of vertebral column turns upward
•
Extends around vertebral column
•
Epicercal: dorsal lobe larger (sturgeon)
•
•
Embryonic fish; hagfish
Hypocercal: ventral lobe longer (flying
fish)
Diphycercal
Homocercal
•
Vertebral column stops short of caudal
fin, which is supported by bony rays
•
Symmetrical
•
Derived fishes
•
3 lobed; lungfish and coelacanth
•
Vertebral column extends to end of
caudal fin, dividing into symmetrical
parts
Spines vs. rays
Bluegill
(Lepomis macrochirus)
Spines
• Rigid
• Never segmented
• Often for defense
Rays
• Flexible
• Often branched
• Mainly for support
Fisheries ecologists use both spines & rays for identification and aging!
External Anatomy
Fins
Sail fish
(Istiophorus platypterus)
American eel
(Anguilla rostrata)
Mouth
White sucker
(Catostomus commersonii)
River hatchetfish
(Gasteropelecus sternicla )
Scales
Longnose gar
(Lepisosteus osseus)
Great white shark
(Carcharodon carcharias)
Mouth placement
superior
Inferior
(sub-terminal)
terminal
External Anatomy
Fins
Mouth
Scales
Sail fish
(Istiophorus platypterus)
White sucker
(Catostomus commersonii)
Longnose gar
(Lepisosteus osseus)
American eel
(Anguilla rostrata)
River hatchetfish
(Gasteropelecus sternicla )
Great white shark
(Carcharodon carcharias)
Scale types
 Placoid
 Ganoid
 Cycloid
 Ctenoid
Placoid:
sharks and rays
“Riblets” decrease drag.
Ganoid:
gar, sturgeon
bowfin, paddlefish,
Armor-like plates for protection
Cycloid and Ctenoid:
•
Overlapping = Flexibility, reduced drag
•
Both grow in concentric rings
most bony fishes (teleosts)
Cycloid: smooth outer edge, soft-rayed
fish (e.g., salmon)
Ctenoid: “toothed” outer edge, spiny fish
(e.g., bass)
Scutes are a
modification of
scales
Modified placoid scales
Snakehead
Muskie
Not all teeth are
pointy!
FISH WITH
TEETH
i.e. Vomerine
teeth
Walleye
Chinook Salmon
Burbot
Longfinned
Eel
Pacu
Gills and Gill Rakers
Structure and function
Barbels: nothing is easier to identify!!
Yellow
Bullhead
Burbot
Brown
Bullhead
Burbot
Lake
Sturgeon
Lateral line
•Sensory organ
•Line of electroreceptor cells
•Used to detect vibrations
Premaxilla
Dentary
Maxilla
Measure anatomy to do ecological studies
Internal anatomy
Kidney
Stomach
Swim bladder
Liver
Heart
Intestine
Ovary
Fat deposits
Red vs. white muscle
 Red (aerobic)
 High capillary density
 Allows adequate oxygenation
 Metabolizes lipids in mitochondria
 White (anaerobic)
 Converts glycogen to lactate
 Lactic acid build up
Cross-section of White
Shark Caudal Peduncle
Resources for Fish ID
Becker Key (ebook available)
WiscFish
FishBase (global)
Get started!
You need:
A partner
A fish
Some tools
The worksheet