All About the Little Fish
Vertebrate Cladogram
Mammals
Birds
Reptiles
Hair/fur
Amphibians
Lobe finned
Ray Finned
Sharks
Jawless
fish
Jaws
Boney
Skeleton
Endotherms
Amniotic egg
Paired appendages
Bones in Pectoral
Fins (Appendages)
Shared Derived
Characteristics:
The trait that
separates one
group from
the others.
Fish Classification
Kingdom:

Animal
Phylum:

Chordates
Subphylum:

Vertebrates
Classes:
1) Jawless Fish (Agnatha)
2) Cartilaginous Fish (Chondrichthyes)
3) Bony Fish (Osteichthyes)
3 Classes of Fish
1. Class Agnatha
Nickname:
Examples:
Jawless Fish
Lamprey, Hagfish
Lack jaws – attach to prey with a
disk-shaped sucker mouth
Elongated eel-like bodies
Lack paired fins & bones
Lack scales
Cartilaginous skeleton
Hagfish traits:
Bottom dwellers
Salt water
No jaws
• have a plate-like
tongue to rip flesh
off organism
Tie themselves into
knots so they can’t
be preyed upon
Hagfish Video
Lamprey traits:
Lack jaws
Sucker mouth
• feed off the
body fluids of
prey
In salt or fresh
water
Lamprey Video
2. Class Chondrichthyes
Nickname: Cartilaginous fish
Examples: Sharks, rays, skates
Skeleton made up of cartilage
Jaws
Paired fins
Predators

carnivores
Scales – PLACOID SCALES
• like sand paper
Internal fertilization
Claspers
Mating sharks
Shark traits:
6-20 rows of teeth


Pointed inward
Immediate replacement
• 20,000 teeth in a
lifetime
Extremely welldeveloped sense
organs to detect prey
Constantly swim
 Or they will sink
 lack air bladder
 Store excess lipids
So they are less dense.
Ray traits:
Has a venom apparatus
or sting at base of tail.
-contains toxin
that causes great pain
and may alter heart rate
and respiration of stung
mammal (Killed Steve
Irwin)
Flat bodies
Bottom dwellers
Give birth to live
young
Diamond shaped
body
Live in fresh and salt
water
Skate traits:
Flat bodies
Bottom dwellers
Long, whip-like tails

No venomous barb
Lay eggs
• “Mermaid Purses”
Triangular body
Live only in salt water
3. Class Osteichthyes
Nicknames: Bony Fish
Examples: Trout, bass, etc..
Jaws
Bony skeleton
Paired fins
Have lungs or swim
bladders
-fill with air for
buoyancy
“Little Nemo”
living in his
Cnidarian
home.
Two major groups of Osteichthyes:
1. Ray Finned Fish
Common fish

Trout, perch,etc..
Fins supported by long
flexible, bony rays
Contains an air bladder
Scales – CYCLOID
• camouflaging for
protection in the water
• similar to rings in trees
The “Penis” Fish (Candiru)
2. Lobe-finned Fish:
Lunged fish and Coelacanth fish:
• have gills and lungs
• live in shallow ponds ~ ponds dry
up, buries self in mud ~ uses lungs
-Have fleshy fins with no rays
Coelacanth fish
• thought to be extinct but recently viewed
 Lack rays
 Has fleshy skin
Evolution
from
water to
land:
Fish adaptations
for life in water
1. Stream-Lined body
Allows them to move without resistance
2. Muscular Tail
Rapid Movement
3. Paired Fins
Maneuver through water
4. Gills
Take in O2 & get rid of CO2
because scales enable diffusion
through the skin.
5. Dorsal Fin
Increases stability
6. Secrete Mucus
Reduces friction as they swim
7. Lateral Line
Row of sensory structures that runs
length of body and are connected to
the brain. Used to detect vibrations
External Anatomy of a Bony Fish:
Adipose fin
Fins:
1) Caudal – for forward movement of fish
2) Dorsal – keep the fish upright and stable
3) Anal – keeps fish moving in a straight line
Used for stopping and
4) Pelvic –
moving up and down
5) Pectoral –
(paired fins)
6) Adipose - only in certain types of fish,
unknown function
Dorsal fins:
-one
-two
-joined
-separated
Operculum: Hyperlink
- hard cover that protects the gills
• CLOSED when water enters the mouth
• OPEN when water comes out the gills
Barbel:
-slender whisker like appendages near the
mouths of certain fish
- notably members of the carp and catfish
families
- have a sensory function
Scales:
Protection
Prevent loss or
gain of water
Other Fun Bionerdy Facts
Fish = pets since 1853
~12M households
July 2005

~646lb Mekong catfish in Thailand
Goldfish = ~ 20 year life span
Dental offices to reduce stress
That’s All Folks!