Download Fish_I - HLWW Public Schools

Fish
Success of Fish




50,000 Vertebrates
Almost 26,000 are fish
9,100 birds; 7,000 reptiles; 4,900 amphibians;
4,500 mammals
Why are there so many Fish
Location of Fish

58% of bony fish are marine
42% of bony fish are freshwater

158 species are found in Minnesota

Fish Variations





Size- from under a centimeter to over 40 feet
Mass- from a few ounces to a few tons
Life span- from a season to 150+ years
Reproduction- you won’t believe some things
fish do
Huge Diversity
Fish






Types
External Anatomy
Internal Anatomy
Movement
Reproduction
Growth and Maturation


Behavior
Water Environments
Types of Fish




Agnatha- Jawless fish; Lamprey, Hagfish
Chondrichthyes- Cartilaginous fish; Sharks,
Skates, Rays
Osteichthyes- Bony fish; “fish” bass, pike,
trout
Placoderms- extinct class of jawed fish
Agnatha
Lamprey

The sea lamprey is an
aggressive parasite -equipped with a toothfilled mouth that flares
open at the end of its
eel-like body.
Lamprey


Fastens onto its prey and rasps out a hole with its
rough tongue
Saliva keeps the wound open for hours or weeks,
until the lamprey is satiated or the host fish dies
Lamprey

Can destroy up to 40
pounds of fish during
12-18 months as an
adult
Lamprey Control



Barrier dams
Safer and more
effective electrical
barriers
Mechanical trapping,
and the release of
sterile male sea
lampreys



Release of sterile male
sea lampreys
Chemicals TFM
Stream velocity
barriers
Non Parasitic Lamprey as Adults

American Brook Lamprey
Northern Brook Lamprey
Southern Brook Lamprey

Adults do not feed


Chondrichthyes
Osteichthyes

Fleshy Finned


Have working lungs
Two main groups



Lung Fish
Lobed finned Fish
Ray Finned- typical “fish”


Spiny Rayed
Soft Rayed
Lung Fish- fleshy finned




Southern Hemisphere
Stagnant ponds and swamps
Surface to breathe air
Aestivate- burrow into mud during dry season
or drought
Lung Fish
Lobed Finned Fish- fleshy finned




Coelacanth- only extant member of the group
(not extinct)
Bottom dwellers
“Walk” on the bottom
Occasionally waddle on land using large
fleshy fins
Coelacanth
Ray Finned

Spiny rayed




Sunfish
Perch
Bass
Soft Rayed


Trout
Minnows
Spiny vs. Soft Rayed




SPINES- Spiny rayed fish have spines in
Dorsal, Anal, and Pelvic fins; Soft rayed do
not
Segmented fins in Spiny Rayed;
Unsegmented fins in Soft Rayed
Location of Pelvic fins
Type of Scales
Anatomy Directions




Anterior- towards the head
Posterior- towards the tail
Dorsal- back
Ventral- underneath, front, belly
External Fish Anatomy








Fins
Tail Shape
Body Shape
Mouth Location
Lateral Line
Scale Type
Miscellaneous
Identification
Fins
Location, use, and number






Dorsal- back, single fin, used for stability, don’t roll
on side
Pelvic- ventral, anterior, paired fin, used for steering,
hovering, and stopping
Anal- ventral, posterior, single fin, used for stability,
don’t roll on side
Pectoral-sides, paired fin, used for steering,
hovering, and stopping
Caudal- tail, single fin, used for propulsion
Adipose- small and fleshy, posterior on tail, single
fin
Spiny Rayed Fins
Soft Rayed Fins
Caudal Fin Shape
Mouth
Different shapes and positions





Superior - mouth oriented up fish often a surface feeder
Terminal - mouth at anterior end, often a midwater
feeder
Inferior - mouth oriented downward, often a bottom
feeder
Subterminal- mouth underneath fish, bottom feeder
Protrusible - mouth can alter shape to be more useful in
suction feeding, can be seen in any of the above but less
common among inferior mouths
Mouth continued
Lateral Line

Senses water currents, pressure, and
movement; line of pores along side of fish
that are fluid filled with a hair like apparatus;
sensory organ
Cycloid Scale


Soft Rayed Fish
Smooth exposed edge
Ctenoid Scales


Spiny Rayed Fish
Ctenii

Teeth on exposed
edge
More Scales




Some fish have NO scales
There are a few other types of scales
Scales are covered in a mucus to protect fish
from infections
Scales can be used to age fish
Miscellaneous External Anatomy


Operculum –Gill cover, protects gills
Vent- external opening to digestive and
reproductive systems, usually directly in front
of anal fin
Odd External Anatomy

Eyes



Smell


Can be used to find mates- pheromones
Taste


Some fish have four eyes
Some eyes are made to be part above water and
part submerged
Some fish have external taste buds all over body
Magnetic Reception

Ability to detect magnetic fields
More Odd External Anatomy

Electroreception




Ability to detect electricity
Found in many fish
Sharks & Catfish use to find prey
Species and sex recognition, social settings,
attacks, submission, courtship,
dominance hierarchies
Identification

http://www.wiscfish.org/fishid/
Internal Anatomy








Spine
Spinal Cord
Brain
Lateral Line
Swim Bladder
Gills
Ears?
Kidneys







Stomach and Intestines
Pyloric Caeca
Vent
Liver
Heart
Gonads
Muscle
Spine



Primary structural framework
Connects to the skull at the front of the fish
and to the tail at the rear
Made up of numerous vertebrae, which are
hollow and house and protect the delicate
spinal cord
Spinal Cord



Connects the brain to the rest of the body
Relays sensory information from the body to
the brain
Sends instructions from the brain to the rest of
the body (main nerve pathway)
Brain



Control center
Both automatic functions (such as respiration)
and higher behaviors ("Should I eat that critter
with the spinning blades?") occur
All sensory information is processed here
Lateral Line



One of the fish’s primary sense organs
Detects underwater vibrations
Capable of determining the direction of their
source
Swim (or Air) Bladder




Hollow, gas-filled balance organ that allows a fish to
conserve energy by maintaining neutral buoyancy
(suspending) in water
Fish caught from very deep water (walleye, lake
trout) sometimes need to have air released from their
swim bladder before they can be released and return
to deep water, due to the difference in atmospheric
pressure at the water’s surface
No swim bladder then will sink to the bottom if they
stop swimming
Primitive Lung?
Swim Bladder continued


Primitive fish used
as working lungs
Still connected in
some fish


Fish gulps air
Not connected in
MOST Bony fish

Tissue secrets or
reabsorbs gas
Air Bladder
“Gut”
Swim Bladder continued




Buoyancy and Density
Increased air More volume Less dense
FLOATS
Decreased air Less volume More dense
SINKS
Lungs came first and became swim bladder
Gills





Site of gas exchange in fish (think lungs)
Water comes in through mouth and out past
gills
Oxygen in and carbon dioxide out
Water has much less O2 than does air
Water needs to be MOVING through gills
Gills continued
Gills continued
Counter Current Exchange

O2 concentration
Ears




Fish are able to hear
Ear bones
Semi circular canals
Ossicle



Modified vertebrae connecting inner ear to swim
bladder
increases hearing greatly
Hard to find
Not present in all fish
Kidneys



Filters liquid waste materials from the blood
Wastes are then passed out of the body
Extremely important in regulating water and
salt concentrations within the fish’s body


Osmoregulation
Allows certain fish species to exist in
freshwater or saltwater, and in some cases)
both
Osmoregulation
More Osmotic Regulation
Osmotic Regulation Review

Freshwater fish



Water is always be absorbed
Have to secrete copious amounts of dilute urine
Saltwater fish




Water is always leaving fish
Drink lots of water
Little urine (usually)
Gills pump out most salt
Stomach and Intestines



Break down (digest) food and absorb nutrients
Piscivorous (eat other fish) have fairly short
intestines because such food is easy to
chemically break down and digest
Herbivorous (eat plants) require longer
intestines because plant matter is usually
tough and fibrous and more difficult to break
down into usable components
Pyloric Caeca



Organ with fingerlike projections located near
the junction of the stomach and the intestines
Function is not entirely understood, but it is
known to secrete enzymes that aid in
digestion
May function to absorb digested food, or do
both
Vent

Site of waste elimination from the fish’s body
Liver



Assists in digestion by secreting enzymes that
break down fats
Also serves as a storage area for fats and
carbohydrates
Important in the destruction of old blood cells
and in maintaining proper blood chemistry, as
well as playing a role in nitrogen (waste)
excretion
Heart

Circulates blood, nutrients, and wastes
throughout the body
Gonads (reproductive organs)

Adult females, the bright orange (generally)
mass of eggs is unmistakable during the
spawning season, but is still usually
identifiable at other times of the year


The eggs (or roe) of certain fish are considered a
delicacy, as in the case of caviar from sturgeon
Adult male organs, which produce milt for
fertilizing the eggs, are much smaller and
white but found in the same general location
Muscle




Provide movement and locomotion
The fillet of the fish
White Muscle
Red Muscle
White Muscle






Short duration
Quick fatigue
Bursts of power (escape/capture prey)
Few Mitochondria
Mostly Anaerobic (not enough O2)
Takes a long time to recover
Red Muscle






Sustained swimming
Hard to fatigue at slow cruising speeds
Many Mitochondria
Usually Aerobically (has O2 to use)
Recovers quickly
Canned Tuna
Spiny Rayed
Soft Rayed Anatomy
Movement

Aquatic movement vs. Terrestrial movement


Terrestrial movement works against gravity and
air friction
Aquatic movement works against density of
water and drag of water
More Movement


Water is 800X more dense than air
50X more viscous

Takes much more energy to move through water
Compensation for Aquatic Environment

Body shape
 Aspect ratio (A.R.)= height/width
relationship



High A.R.= reduced drag and high sustained
speed; Marlin, Tuna
Low A.R.= broad surface area, high drag,
quick and powerful starts; Bass
Body covering helps reduce drag; Mucus
Body Shape and Swimming Style

Anguilliform




Trunk and Tail; only head doesn’t move
Body moves in S shape motion
Allows for forward motion, braking, and reverse
Larval fish, Eels, Lampreys, and Sharks
Body Shape and Swimming Style

Subcarangiform




Roughly 2/3’s to 1/2 of fish moves side to side
Allows for rapid acceleration
Bass, Salmon, trout, minnows
Carangiform

Posterior 1/3 moves
Body Shape and Swimming Style

Thunniform





Tail hinged to body
Caudal Peduncle and Tail move
Low drag
Sustained high speeds
Marlin, Sailfish, and Tuna
Body Shape and Swimming Style

Ostraciliform


ONLY tail moves; Body canNOT
High Drag
Swimming Style continued
Swimming Style continued
Other Swimming Style


Not all fish use Caudal Fin for propulsion
Some fish use other fins




Dorsal Fin
Anal Fin
Pectoral Fins
Generally these are found in Marine
environments
Movement Oddities



Walk on bottom
Walk on land
“Fly” through air
Reproduction

Oviparous



Ovoviviparous


Lay eggs that hatch OUTSIDE the body
Most common
Eggs develops inside the oviduct, nourished by
egg yolk, eggs hatch in the uterus
Viviparous

Young develop within the uterus, nourished
through placenta, Live Birth
Reproduction

Fecundity



Number of eggs shed in each spawn
Varies from one to hundreds of thousands
Number of eggs is related to amount of parental
care involved and the success of each egg
reaching maturity
Reproduction continued






Fish spawn in shallows
Deep over structure
Flood plains
Capable of spawning multiple times
Often spawn at the same place they hatched
Dioecious


Separate male and female
This is where and how it always happens, RIGHT?
More Reproduction

Anadromous fish



Fish that return to their spawning rivers from the
ocean at certain seasons for breeding in fresh
water
Born in small streams, mature in the ocean, use
smell or magnetic field to return to stream where
they hatched- thousands of miles, length of time
spent in stream after hatching and length of time
in ocean varies
Salmon
Anadromous fish

Semelparous
 All die after
reproducing
 Pacific Salmons;
King, Silver,
Sockeye, Chum,
Pink
Anadromous fish

Iteroparous


Can spawn multiple times
Atlantic Salmon, Steelhead (rainbow trout)
Reproduction continued

Catadromous



Fish live in fresh water
Breed and spawn in the sea
Eel
Reproduction- Starting to get Weird

Parthenogenesis

Females produce fertile eggs without fertilization
This may occur in multiple species of fish
Also can happen in other reptiles, amphibians,
birds, and lower organisms
Not common

Could it happen in humans?



Komodo Dragon
There have been two reported cases of Komodo dragon "virgin births"
Komodo dragons
The largest lizards in the world are capable of "virgin births".
Scientists report of two cases where female Komodo dragons have
produced offspring without male contact.
Tests revealed their eggs had developed without being fertilized by
sperm - a process called parthenogenesis, the team wrote in the
journal Nature.
One of the reptiles, Flora, a resident of
Chester Zoo in the UK, is awaiting her
clutch of eight eggs to hatch, with a
due-date estimated around Christmas.

BBC News
Reproduction Craziness



I’m not making this stuff up
Think “Jurassic Park”
Things to think about while sitting on the ice
Reproduction Craziness 1

When the dominant male of group dies,
largest female becomes the male
Reproduction Craziness 2



Breeding female is the largest of the group
When it dies, the male becomes the breeding
female
The largest juvenile becomes the male

Remain member of the group stay in as juveniles
Reproduction Craziness 3


Capable to switch back
and forth from male to
female
Bluehead Wrasse
Reproduction Craziness 4


Begin the spawn as females and end the
spawn as males
Some Sea Bass species
Reproduction Craziness continued

When fish switch sexes


Can occur once or switch back and forth multiple
times
Length of time required varies from a few hours
to a few days
Reproduction Craziness continued


Asexual Fish
Some fish species
normally have
both male and
female
reproductive
organs
Reproduction Craziness 5


Have two distinct types of
males, one takes longer to
mature and grows larger,
builds and protects nests,
hums to attract females;
other is smaller, matures
quicker, not involved in
any courtship, sneaks into
nests to mate
Midshipman
Growth and Maturation

General pattern





Egg
Larva
Juvenile
Adult
May go through Metamorphosis


Transformation form larval stage to adult
Tadpole to Frog
Age and Size at Maturation

Older



Younger




More eggs
May die first
Fewer eggs
Reduced growth
Weaker state if they reproduce
Fish under heavy pressure reproduce sooner
Metamorphosis

Lamprey


Flounder


Ammocoetes to adult.
Only as adult are they flat with both eyes on one
side
Caused problems early with identification
Fish Age and Growth by Scales





Use growth rings
Annulus
3 growth rings
on this scale
Fish is 3 years
old, going on
4
3 yr old age class
Fish Age and Growth by Otolith

Ear bone
Fish Age and Growth

Mark Recapture



Catch and tag fish
Re-catch later
Many different
formulas
Fish Behavior


Fish as Prey
Fish as Predators
Fish as Prey

Anti Predation






Avoid detection
Evade pursuit
Prevent and deflect attacks
Discourage capture
Discourage handling
Why can’t fish just hide all day long?
Avoid Detection





Camouflage
Invisibility
Swim with Others
Detect predator before it finds you
Sound or electrical insulation
Camouflage

Look like your
background

Body growths
 e.g.
Seadragons
Camouflage

Look like your background


Background matching coloration
 Light ventral surface, dark dorsal surface
 e.g. flatfish change color and pattern
Reduced movement
Camouflage

Mimic a non-prey item



Plant material
Toxic fish
Disruptive coloration


Body covered in regions of contrasting colors (e.g.
vertical bars or spots)
This breaks up the outline of a fish making it less
recognizable as a potential food item
Disruptive Coloration
Invisibility

Countershading





Pattern on the fish opposite to patterns of light in
the water
Dark on top, light on bottom
When viewed from the top the fish blends into the
dark background of the water
When viewed from the bottom the fish blends
into the light background of the sky
Works for all viewing angles
CounterShading
Invisibility

Silvery Sides



Open water species
Covered in small “mirrors”
Transparency



Larvae and juvenile fish
Clear muscles and bones
Brain, eye, gonads can’t be clear
Silver Sides
Transparency
Swim with Others




Lower probability of detection for an individual in a
school than an individual on its own
Predators go after differences
Prey can act as a group aggressively towards
predator (i.e. mobbing behavior)
Predator inspection
 Single fish go out and evaluate predator
 (i.e. somebody drew the short straw)
Schooling
Evade Pursuit



Discourage Predator
Move to Shelter
Open Water Escape
Discourage Predators



Spines
Toxic skin/internal organs
Make use of aposematic coloration or
behavior


Bright, conspicuous coloration and/or slow
escape response
Signal to predator that they are dangerous
Move to Shelter




Go where predator cannot
Bottom sediments
Shallows
Rocks
Open Water Escape





Outrun, out maneuver, or out fly!
Most prey can’t outrun their predators
because they are smaller
They may be able to out maneuver
Flying fish “fly” (i.e. jump and glide) out of
the water
Others jump out of water to confuse and
disorient predators
Prevent and Deflect Attack



Prevent with last second evasive move
Deflect with structural defenses (i.e. spines,
etc)
Prevention of attack by group foragers


Dilution effect = individual probability of being
consumed decreases with increasing group size.
Confusion effect = Predators become confused by
so many prey and switch targets too often to
actually catch many prey
Discourage Capture

Take advantage of gape limitation


Static or dynamic adaptations associated with
body size/shape




Mouth size
This makes it difficult to handle prey
Elongate spines or fins or very deep body
Blow up (e.g. pufferfish) or erect spines (e.g.
bluegill)
Chemicals released when attacked
Discourage Handling


One way spines (think tire spikes)
Mucus excretion


Taste very bad
Releasable scales
Fish as Predators





Searching
Pursuing
Attacking
Capturing
Handling
Searching

Active



Make use of all senses
Speculation searching
Passive




Buried by sediment
Projections and color have evolved to match substrates
for “camouflage”
Passive water column predators just hang in water
column
Most passive predators use vision to detect prey
Active versus Passive

Passive = Energy savings, but rely on prey
coming to you



May be risky to wait for prey, but don’t spend
energy looking
Tradeoff between certainty of prey capture and
energy spent catching prey
Two different strategies to solve the same
problem
Pursuit



Chasers
Deceivers
Stalkers
Chasers

Sustained Chase


Maneuvering


Streamlined
Big tails and fins for complex environments
Fast Starts



Lie in wait predators
Fins far back on body
Fast start but little endurance
Deceivers


Lure prey within striking distance
Make part or all of their bodies look like food
for prey
Stalkers

Many of these fish approach prey head on and
make use of disruptive coloration




Split head color pattern
Visually breaks up shape of whole head
Prey have delayed recognition of predator
Similar to big cats
Attack and Capture




Ideally predator attacks by overtaking prey
with simultaneous mouth extension and
suction
Fast-start predators overtake prey
Lie-in-wait predators have great suction
capacity; Largemouth Bass
Some fish swim and passively sieve prey
from water
Large Mouthed Bass
Attack and Capture continued


Some immobilize prey during attack and then
“capture”
Predators often separate out individual prey
from the prey’s shoal or school


Greatly increases success rate of predation
Attacks on “stragglers” more likely to be successful
Attack and Capture- Just For You

Predators often attack those prey that are
different within the shoal


Produces strong selection towards morphological
and behavioral uniformity within schooling prey
species
Don’t be different, you will be eaten
Handling

Post-capture manipulation




Aids in ingestion and digestion
Reducing size of prey (i.e. tearing it apart)
Get prey to go in head first- makes it easier to
swallow
Teeth vary according to prey
Generalist vs. Specialist

Generalists = Predators that make use of
multiple resources and behaviors


Perch sit-and-wait and pursue)
Specialists = Predators that exploit only one
resource or use only one type of behavior

Pike only sit-and-wait
Water Environments




Lake Zones
Lake Stratification
Lake Nutrients
Dissolved Oxygen
Lake Zones

Littoral Zones


Pelagic Zone


Light cannot penetrate to the bottom
Photic Zone


Light reaches bottom
Depth that light reaches
Profundal Zone

Depths beyond where light can penetrate
Lake Zones
Lake Stratification

Water of different temperatures have different
densities




Warm water is less dense than cold water, it
RISES
Cool water is more dense than warm water, it
SINKS
 For water above 40 degrees
Water is MOST dense between 38-40 degrees
Water is least dense at 32 degrees
Lake Stratification

Epilimnion



Hypolimnion



Upper layer
Warmer water
Lower layer
Cooler water
Thermocline

Transition between the two layers
Lake Stratification

Lakes Turn Over twice a year



Occurs in Spring and Fall
Due to warming and cooling temperatures
Mixes temperatures and nutrients
Lake Nutrients

Oligotrophic


Mesotrophic


Good clarity and average nutrient level
Eutrophic


Clear, low plant life, LOW nutrients
Enriched with nutrients, high plant growth, algae
blooms
Hypertrophic

Excessively enriched with nutrients
Oligotrophic
Eutrophic and Hypertrophic
Eutrophic and Hypertrophic
Dissolved Oxygen



Oxygen put in water through Photosynthesis
and water movement that traps air bubbles
Dissolved Oxygen is needed for fish survival
Concentrations may get low in Winter


Winter kill or ‘lake froze out’
Concentrations may get low in Summer

Why?
Dissolved Oxygen in Summer
Dissolved Oxygen continued

How might this be applied to where you fish and
the depths at which you fish?
Mn Fish by Families














Bowfin
Bullhead Catfish
Burbot
Drum
Freshwater Eel
Gar
Goby
Herring
Killifish and Topminnow
Lamprey
Livebearer
Minnow
Mooneye
Mudminnow














Paddlefish
Perch
Pike
Pirateperch
Sculpin
Silverside
Smelt
Stickleback
Sturgeon
Sucker
Sunfish
Temperate Bass
Troutperch
Trout