Transcript Ch. 33 - Fish

Ch. 39 - Fish
How many of you have a fish aquarium?
What are some types of fish?
What makes a fish different from other
animals that we have talked about?
– Vertebrates
What phylum do vertebrates belong to?
– Chordata
Video
Classification of Vertebrates
Kingdom: Animalia
– Phylum: Chordata
• Subphylum: vertebrata
All chordates at some stage develop 3 things.
1. Notochord – dorsal rod of specialized cells.
2. Dorsal nerve cord- hollow tube just above
the notochord.
3. Pharyngeal pouches – small outpockets of
the anterior gut.
Most have a post anal tail
3 Classes of fish
1. Agnatha – means “jawless”
– Lampreys & hagfish
– Both have a notochord their whole life.
– Lamprey are mainly freshwater
– Hagfish are marine
– Hagfish have a toothed tongue that saws a hole in
its prey
– Pg. 803
Video
Chondrichthyes (class) #2
Sharks, rays, & skates
Movable jaws; unlike agnatha
Placoid scales – tooth-like
spines on their skin.
Pg. 817
Video
Shark Characteristics
Very fast side-to-side swimming motion
Have 6-20 rows of teeth pointing backwards.
Why?
Can use more than 20,000 teeth in its lifetime.
They have 2 pectoral fins just behind their
head that act like wings. They compensate for
the thrust of the tail fin.
Video
Rays & Skates
Rays have more of a disk-shaped body
Skates have a triangular-shaped body
Both have flattened bodies
Both have great camouflage and hide
well in the sand.
Sting rays have a very powerful sting.
Video
Osteichthyes (class) #3
3 types of bony fish
1. Lobe-finned fish
– For over 70 million years scientists thought this
fish was extinct until 1938 a South American
fisherman caught one.
2. Lungfish
– Can live out of water for long periods of time.
3. Ray-finned fish
– Have fins supported by bones(rays). Most fish
are this type. Examples?
External Anatomy of a Fish
Yellow Perch  Perca flavescens
Operculum – hard covering that protects the
gills on each side.
Caudal fin – tail fin (thrust)
2 Dorsal fins
1 Anal fin
2 Pectoral & Pelvic fins
– Helps steer, brake, & move up and down.
Integument – skin
–Scales that overlap like shingles
–Contain chromatophores, which are
cells that allow the fish to change
colors.
Lateral line – senses vibrations (no ear)
Internal Anatomy of a Fish
Food Passage:
Pharynx  Esophagus  Stomach 
Pyloric ceca (intestine)
The pyloric ceca are outpockets of the
stomach, that have lots of villi that line it.
Circulatory System
2-chambered heart
Atrium – collecting chamber
Ventricle – pumping chamber
The blood is pumped through arteries to
small capillaries in the gills for has
exchange. The blood then returns to the
heart through veins.
Respiratory System
Gills with a large surface area
Swim bladder allows the fish to
adjust its density so it can float
without using much energy.
Nervous System
5 lobes of the brain
1. Optic lobes – the largest lobes, for
sight.
2.Olfactory lobes – smell
3. Cerebrum – intelligence
4. Cerebellum – balance
5. Medulla oblongata – regulates
interior organs.
Reproductive System
Separate sexes
1. External Fertilization – occurs when
the eggs are fertilized outside the
female’s body.
–Ex. Salmon, trout, perch, (most species)
2. Internal Fertilization – occurs when
the eggs are fertilized inside the body.
–Ex. Guppies, swordtails, mollies
Spawning is the release of the eggs.
Milting is the release of sperm.
What is one way fishes protect each
other?
–Schools of fish
What is the age limit on a fishing
license?
–16 -65