1. Chapter 19
Fish

2. Fish outline Diversity of species Bony fish
Anatomy and Physiology of bony fish
Special organs of bony fish
Spawning
Parental care
Cartilaginous fish

3. Diversity of Species
Fish are cold-blooded, water-dwelling vertebrates with gills and scales.
There is more variety among fish than all other land and water vertebrates combined!!!

4. Bony Fish “Osteichthyes”
Skeleton made of partially or wholly bone
The most abundant fish – 95% of all known fish
Goldfish, cod, catfish, bass, salmon, tuna, and many others!

5. Structure of Bony Fish Three main body regions: head, trunk, tail
Features of the head
nostrils – used for smell
for taste, the taste buds are spread over the body of the fish
gills – covered by gill coverings known as opercula, which protect the gills.

6. Structure of Bony Fish Features of the trunk and tail
The largest part of the body is the trunk
The most prominent features on the trunk and tail are the fins
The fins are called “rayed fins” due to the webbing
Most have two sets of paired fins – the pectoral fins and the pelvic fins

7. Structure of Bony Fish Most also have vertical fins which are unpaired
includes the dorsal fin
the anal fin
the caudal fin – tail
Skin and Scales
most have a tough skin
the skin has mucus cells which make the fish slippery
the skin has chromatophores which give it color

8. Skin and Scales Most bony fish have fairly tough skin
The skin contains mucous cells to make the fish slimy – and gives the fish their “fishy” smell
The mucous serves three purposes:
1. waterproof
2. protection from parasites
3. reduction of friction as it moves in water

9. Skin and Scales
Many contain Chromatophores – cells that give the fish its color
Many have scales
Scales do not increase in number as the fish grows – the scales simply grow larger
The scales of many fish even have growth rings – which aid in determining the age of a fish

10. Skeleton Backbone – contains individual vertebrae of bone or cartilage
Backbone – also has spine-like extension
Cranium – encloses the brain
Pectoral girdle and pelvic girdle – support the fin

11. Muscles Has all three of the basic muscle types 1. Skeletal 2. smooth
3. cardiac
Cardiac – heart
Smooth – digestive organs
Skeletal – “fleshy” part of the fish – the part you eat

12. Muscles
Unlike vertebrates, a fish skeletal muscles are arranged in “W” shaped bands
Myomeres – what the “W” shaped bands are called
Each myomere is controlled by a separate nerve, allowing the fish to move through the water in wavelike motion.

13. Respiratory System Fish breathe right in the water
Gills – A fish can extract 80% of the oxygen from water – people only get about 25%
Protecting the gills – They are covered by a wide plate of bone (operculum)

14. Respiratory System
Fish are continually allowing water to “rake” over their gills as they “inhale”
If the fish is still it uses its mouth
If swimming, the water flows into the mouth and out the gills
Some sharks can only breathe by moving

15. Circulatory System
The circulatory system is closed, consisting of arteries and veins similar to mammals
Fish have no lungs – as a result the circulatory system is quite simple
The fish has a two chambered heart
Blood flows from the heart to the gills
After oxygen is in the blood from the gills, the blood moves to the body
The blood then returns to the heart to be pumped back to the gills for more oxygen

16. Digestive and Excretory Systems
The most numerous of all fish are plankton-eaters
The carnivores are less numerous, but have more variety
The carnivores may eat insects to other fish

17. Digestive and Excretory Systems
From oral cavity to stomach
Oral cavity (sometimes with teeth) → pharynx → esophagus → stomach
Digestion – food is mostly digested in the stomach
Digested food then passes through the intestine
Waste exits the anus near the anal fin

18. Digestive and Excretory Systems
Excretion of liquid waste
Freshwater fish are continually taking in extra water and therefore must produce a lot of urine.
Saltwater fish are continually losing water and therefore must ingest large quantities

19. Nervous System Senses of the fish
A typical bony fish has very good eyesight
It has no eyelids
They focus by changing the shape of the eye
Most fish can hear very well

20. Nervous System
Fish can sense faint vibrations and pressure changes by its “lateral line”
Lateral line – a system of nerve endings that extend over its head and sides
The lateral line allows it avoid obstacles or predators
Fish have excellent sense of smell

21. Reproductive System
In both sexes, sex cells (eggs and sperm) are released through the urogenital openings.
Most bony fish reproduce by external fertilization – eggs are fertilized outside the body of the female.
When fish are ready to spawn (lay eggs) they may congregate or migrate to the place they were hatched.
The eggs (called roe) are laid in the water by the female .
The male releases “milt” which contains the sperm.
Once fertilized the egg begins to develop into a young fish

22. Reproductive System
Most fish protect their nest of eggs and then the young fish after they are born.
The young fish (called a “fry”) is large enough to find its own food when hatched.
A female may lay as many as a million eggs, but only a fraction of them survive and hatch and produce fry.

23. Special Organs
Swim Bladders – a hollow gas-filled chamber located near the top of the bony fish.
It allows the fish to become stationary.
The swim bladder is filled with gases by a special “gas gland”.
Not all fish have a swim bladder.

24. Special Organs Light and electricity generating organs.
Many deep sea fish have light organs that enable them to see in the murky depths.
The electric eel can generate electricity and can deliver a discharge of 600 volts.

25. The Cartilaginous Fish
There are two classes of Cartilaginous fish
Class Chondrichthyes: Sharks, rays, and chimaeras
Class Cyclostomata: Lampreys and hagfish

26. Class Chondrichthyes Sharks, rays, and chimaeras Only 3% of all fish
All have jaws and cartilaginous skeletons.
They are all covered with “tooth-like” scales that make the fish feel as though covered in sandpaper.

27. Sharks Sharks lack a swim bladder
They have a complex reproductive system – they give birth to live young.
Due to a lack of swim bladder, sharks must continually move and some never sleep because of this.
Sharks have the best sense of smell of all fish.
Attacks on humans are rare.

28. Rays Rays have large flat bodies and whip-like tails
The most dangerous ray is the stingray which is responsible for more injuries to humans than all other fish combined!!!
The largest is the manta rays – a gentle giant – it can grow up to 25 feet!

29. Chimaeras
Chimaeras – also known as the elephant fish

30. Lampreys and Hagfish
Lack jaws
Make up less than 1% of all fish.