FISHES (yes, that’s the proper
word)
ICHTHYOLOGY (the study of fish)
• MARINE VERTEBRATES; FISHES CHAP
6.
• Read pgs. 177-187
• covering the topics of
– phylogeny, evolution and anatomy
History of Ichthyology
(don’t write this, just read)
• Aristotle made first written recordings and
observations about fish (300s B.C.)
• For 2,000 years no work done on fish
• Then in 1500s, three scientists published new
works on fish
• Led to rapid expansion in knowledge and new
interest in study of fish
• Linneaus and modern classification of fish
• 20th century sees diversification of ichthyology
Fishes Are Diverse (don’t write this, just read)
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Live in diverse habitats
Have different body shapes
Have different body structures
Have different reproductive strategies
Have different feeding styles
Inhabit multiple niches in life cycle
Fishes are very diverse
I’m not kidding, they are really diverse
I. GENERAL INFORMATION
• cold-blooded, vertebrate
that breathe w/gills and
move w/fins
• most numerous
vertebrates more than
30,000 species
• 400-500 in the reef area
• smallest
– Philippine Island Goby –
1/3”- 1/2”
• largest
– Whale Shark – 50’ and
several tons
Diversity of Body Plan
Diversity of Body Plan
Rover-predator
Tuna, swordfish, bass,
trout
Lie-in-wait
Pikes, barracuda,
gars
Bottom rover
Catfishes, sturgeons
Surfaceoriented
Four eyed fish,
killifish
Bottom clinger
Sculpins, gobies,
clingfishes
Rattail
Flatfish
Deep-bodied
Perch,
Chimeras,
brotulas
Eel-like
Common Body Plan Descriptors
Elongate,
fusiform, or
basslike
Anguiliform,
eellike, or
attenuated
Ovate or
truncated
Compressed,
compressiform,
thin, narrow, deep,
or perchlike
Depressed,
depressiform, or
flattened
Globiform,
subcircular, or
hemispherical
II. ANATOMY
A. Body shape
Front
• FUSIFORM
• COMPRESSED
• DEPRESSED
• ATTENUATED
Side
II. ANATOMY
A. Body shape
Front
• FUSIFORM
• COMPRESSED
• DEPRESSED
• ATTENUATED
Side
B. Mouth Position is significant
• ambush
• predator
• bottom feeder
B. Mouth Position is significant
• ambush
• predator
• bottom feeder
C. Feeding Patterns (pg. 187-191)
• Predators
• Nibblers- crushing teeth, may eat coral polyps
and stone
• Strainers- plankton feeders
• Suckers- disc w/lips, barbels (whiskers) for
searching the sand
• Parasitic- (external or internal) rasping teeth to
penetrate scales
ex. hagfish and lamprey
ex. canduri or vampire fish -suck blood from
gills
• read passage from text
D. Know fin names and functions
from handout
FISH ANATOMY
• FINS – movable structures
that aid the fish in
swimming and maintaining
balance
• May be sharp, spiny or soft
• Most have: Dorsal fin
Anal fin
Caudal fin (tail)
Pectoral fin
Pelvic fin
Adipose fin
(only some)
Fish live
(background information)
• 13% associated with open ocean
• 1% in surface (epipelagic) layer
• 5% in unlighted sections of water column
(deepwater pelagic fishes)
• 7% on bottom (deepwater benthic fishes)
• 78% of marine fishes (44% of all fishes)
live in narrow band along continents in
water less than 200m (continental shelf)
Fish Diversity
• By volume 97% of all water is marine
• 58% of fish species are marine, 41% are
fresh water
– Mainly due to speciation in response to
isolation (ponds, lakes, rivers)
– Close to 80% of all marine species live in
water along coastlines less than 200 m deep
III. EVOLUTION
• Draw diagram from
Marine Biology Text pg. 179
• Phylogenetic Tree
–(shows evolutionary
relationships)
• Emphasis on Fish Classes
EVOLUTION
(background information)
• Earliest fish – Ostracoderms
• fossils date to the Ordovician
Period – 425-450 Million
years ago
• slow, bottom-dwelling w/thick
bony plates and scales,
poorly developed fins and no
jaws
• believed to be first animal
w/a backbone
• became extinct 250 million
years ago
IV TAXONOMY
• Kingdom
Animalia
• PhylumChordata
– dorsal nerve chord
• Subphylum Vertebrata
– dorsal backbone made of cartilage or
bone
• Classes
– Agnatha
– Chondrichthyes
– Osteichthyes
Class Agnatha “jawless”
• Do not have a lateral line system
• Cyclostomes “round mouths” ; have neither plates nor scales
• Notochord, eel-like shape, a cartilaginous skeleton, and
unpaired fins
Lampreys:
- free living or parasitic; adapted for sucking blood and body
fluids of other fish
- Feeding: attach by suction, tear a hole with toothy tongue,
secrete chemical to prevent clotting
- do not have a stomach: mouth, esophagus, a straight
intestine, and associated glands
Problem for great lakes sport and
commercial fishermen
Hagfish
(for background information)
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Bottom dwellers in cold marine waters
Scavengers of dead and dying fish on ocean
bottom
Feed by sawing the fish with its toothed tongue
from the inside out
Extremely flexible to avoid capture or to clean
the slime off after self-defense secretions
When not feeding they remain
hidden in burrows on the ocean
floor
Class Chondrichthyes
(cartilage fish)
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Sharks, skates, and rays
They have skeletons of cartilage, not bone
Also have movable jaws and skeletons with paired fins
No swim bladder
Sharks
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Sharks are scavengers that eat injured fish, carrion, garbage and other
waste from ships as well as animals such as seals, turtles, birds, whales,
crabs, and a wide range of fishes.
The shark’s mouth has 6 to 20 rows of backward-pointing teeth. They can
detect blood from an injured animal as far as 500 miles away.
They swim with a side-to-side motion of their asymmetric tail fins. Behind
their heads are pectoral fins that jut out of their bodies like the wings of a
plane.
Gas exchange requires a continuous passage of
water over a shark’s gills.
Rays and Skates
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Skates are a family of flat-bodied rays found in warm and
temperate seas. They have eyes located on the upper
surface of the body while the mouth and gills are located
on the lower surface.
Their color makes them almost invisible because when
another animal looks down on them, they are
camouflaged with the darkness of the sea bottom. When
looked up from underneath, the animal is camouflaged
with the light from the sun.
Water enter their gill through two openings
called spiracles atop their heads. Most feed on
mollusks and crustaceans.
Osteichthyes (bony fish)
• Osteichthyes make up most of the vertebrate
population in fresh water and in salt water.
• Ray-finned fishes have fins that are supported by
the long bones called rays. They are the most
familiar fishes and include snakelike eels, yellow
perch, cave fish, herring, and lantern fish.
• Lungfishes have gills where gas exchange takes
place between water and the blood. They burrow
unto the mud and cover themselves in mucus to
stay moist until the pond refills.
• Lobe-finned fishes, or
coelacanths, have
paddle like fins with
fleshy bases.
• Lobe-finned fishes, or
coelacanths, have
paddle like fins with
fleshy bases.
V. PHYSIOLOGY (fishyology)
• Diffusion- moves O2 from water into the blood
(hemoglobin)
• the LARGE SURFACE AREA of the gills
facilitates diffusion the gills are HIGHLY
VACULARIZED
• ***Lung fish- modified SWIM BLADDER
vascularized. Gaseous O2 can diffuse into the
blood stream. Some fish can gulp air.*****
• chromatophores (pigment cells)
FISH ANATOMY
• GILLS – organs on
the side of fish that
allow them to breath
• Water is drawn in
through the mouth
and out the gills
• Dissolved oxygen in
the water is taken into
the blood and carbon
dioxide is released
Draw and label the gill, gill arch, gill rakers
FISH ANATOMY - EYES
• similar to other
vertebrates, but differ
in a couple of ways:
– spherical lens
– no eyelids
– size of the eye
depends on the
amount of light
reaching the eye
• Shallow water – small
eyes
• Deep water – large eyes
• Dark caves – blind
FISH ANATOMY- ears, taste, smell,
sensitive cells
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Have inner ears
Have taste buds in their mouths,
on their lips and on their body/fins
Have highly developed sense of
smell
• Fish react to changes
in water pressure,
temperature, currants
and sounds
w/pressure sensitive
cells along a lateral
line near the base of
the tail
Do fish drink water?
• Yes and No
• It depends on the type of water it lives in.
• VI. REPRODUCTION synonym
spawning
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Sperm
milt
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Eggs
roe
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Reproduction is determined by
• 1. Age and 2. Season
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Types?
• Egg laying - most bony fish
• Live bearing- internal fertilization and
internal development. Not very common,
pioneered by Chondrichthyes
Reproductive strategies
• Hermaphrodites• Sex reversal- is it better to be female or male?
• Unique methods to protect laid eggs
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Camouflage
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Mouth incubation
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Guard the nest
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EXTERNAL
DEVELOPMENT
INTERNAL
DEVELOPMENT
• EXTERNAL
DEVELOPMENT
• Many eggs
few eggs
INTERNAL
DEVELOPMENT
few eggs
• EXTERNAL
DEVELOPMENT
• Many eggs
• No care
few eggs
guard
INTERNAL
DEVELOPMENT
few eggs
incubate
• EXTERNAL
DEVELOPMENT
• Many eggs
few eggs
• No care
protection
INTERNAL
DEVELOPMENT
few eggs
incubation
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Few survive
higher % survive
highest % survive
• EXTERNAL
DEVELOPMENT
• Many eggs
few eggs
• No care
protection
INTERNAL
DEVELOPMENT
few eggs
incubation
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Few survive
• 10/1000
higher % survive
10/100
highest % survive
10/10
• ENERGY/ BENEFIT RATIO
• A limited amount of energy can be shared
in different ways. % of survival is different
but overall numbers remain about the
same