Chapter 31: The Fishes
Class Osteichthyes: Notes On The Bony Fish
1. Come in a variety of sizes and structures.
2. 90% of all fish are members of Class Osteichthyes.
3. The Perch is a typical member of this class.
Characteristics of the Osteichthyes
A. The external anatomy of the Perch shows it to have:
1. A mouth
2. Two eyes
3. Gill covers called operculum
4. A pair of pectoral fins
5. A pair of pelvic fins
6. An anal opening
7. An anal fin
8. A caudal fin
9. A lateral line down each side of the body
10. An anterior dorsal fin
11. A posterior dorsal fin
12. Scales
13. A pair of nostril openings
B. Digestion in the perch: The digestive system consists of:
1. The mouth
2. The esophagus
3. The stomach
4. The intestine
5. The pyloric caeca
6. The liver (which produces bile)
7. The gall bladder (stores bile)
8. The anal opening
Internal anatomy of the Perch
C. Excretion in the Perch:
1. Kidneys remove nitrogen wastes from the blood.
2. Urine is removed through the urogenital opening.
D. Circulation and gas exchange in the Perch:
1. Heart (2 chambered)
2. Arteries (carry blood away from the heart)
3. Veins
4. Capillaries
5. Sinus Venosus
6. Atrium
7. Ventricle
8. Ventral aorta
9. Dorsal aorta
Path of blood during circulation:
veins----->sinus venosus----->heart----->atrium----->ventricle------>ventral aorta----->
gills(gill capillaries)------>dorsal aorta------>to all parts of the body--------->veins
10. Operculum protects the gills
11. Gill arches support the gills
12. Gill rakers prevents large particles from passing through gills
13. Gills carry out gas exchange
14. Swim bladder determines depth that fish swims (air comes from the blood)
E. The Perch's Nervous System Consists of:
1. The olfactory bulb (smell)
2. The lateral line (pressure detector)
3. The optic lobes (vision)
4. The cerebrum (memory and learning)
5. The Cerebellum (balance and muscle control)
6. Medulla (involuntary functions)
7. Cranial nerves (branch from the brain)
8. The Spinal nerves (branch from the spinal cord)
F. The Perch's Senses:
1. Semicircular canals (balance)
2. Lateral line (allows swimming in close formation without collisions)
3. Nostrils (olfactory sacs) (smell)
4. Eves (optic lobes)(vision)
The Perch's Brain
G. Reproduction In The Perch:
1. Males produce sperm in testes; females produce eggs in ovaries
2. Sperm is released into the water as a watery mixture called milt
3. Fertilization of eggs takes place in the water
4. Young are independent after hatching (no maternal care at all)
H. Adaptations Of The Bony Fish:
1. Salt Water fish:
a. Gills transport excess salt from the body
b. Urine is produced in very small amounts (highly concentrated with salt-preserves water)
4. Fresh Water fish:
a. Gills transports salt into the body
b. Kidneys produce large amounts of urine
c. Only fish such as the salmon can go from a life in fresh water to life in salt water and back
(kidneys reverse the above processes)
5. Life Cycles Of Salmon: hatch in fresh water-------->move to salt water (oceans)------->return to
fresh water as adults-------->reproduce and then die.
6. Feeding Habits: Barracuda------predators; Parrot Fish uses a hard beak tooth to scrape algae from rocks;
Angel Fish have worm-like appendages that attracts prey like a worm on a fish hook attracts fish.
I. Fossil Osteichthyes: The Coelacanth (SEE-luh-kanth)
a. Was thought to have become extinct about 70 million years ago
b. One was caught in a net in the Indian Ocean in 1938
c. Scientists dubbed this fish as a "living fossil"
J. Other Adaptations:
1. Coloration
2. Deep-ocean fish (able to exist at great depths)
3. Reproductive behavior
4. Lung fish (a fish with a primitive lung)
K. Systems In The Perch: Eight Systems Operate In The Prech
1. Digestive System
2. Excretory System
3. Circulatiory System
4. Nervous System
5. Reproductive System
6. Respiratory System
7. Skin/Scales
8. Skeletal System
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