1. Class Osteichthyes
aka: Bony Fishes

3. Body Shape Body shape is directly related to the niche of the fish
Streamlined fish are fast swimmers
Laterally compressed fish are lazy swimmers that are capable of burst of speed
Bottom feeding fish are often flat with eyes that point upwards
Eel like body shapes allow for the animal to hide in tight spaces
Body shape can also aide in camouflage
The animal can be adapted to look like the vegetation it is living in

4. General Characteristics
Have a skeleton made at least partially of bone
Makes up almost half of all vertebrates
Skin is composed of cycloid scales
Thin, flexible, overlapping tissue
Gills are covered by a flat of bony plates and tissue called the operculum
Fins are generally composed of thin tissue supported by spines
The mouth is located at the tip of the body and is jointed to allow for a wide range of movement
Have a swim bladder to control buoyancy

5. Streamlined
Laterally compressed
Eel
Flat Fish

7. Coloration
The color for the fish is found in specialized cells called chromatophores
Irregular in shape
Capable of almost any color in the rainbow
Give the fish the ability to change color by contracting and expanding the chromatophores
Some fish have iridophores which are cells that reflect a certain wavelength of light
Color is used for camouflage, warning coloration or countershading

9. Movement Most fish swim with an S motion
A rhythmic side to side moving from the head to the tail
Controlled by bands of muscle called myomeres
Run parallel along the sides of the fish
Visible in fish you eat
Makes up 75% of the fishes weight
White muscle is used for bursts of speed
Red muscle is used for constant locomotion
The fins are used like rudders to change direction in the water
Some fish move by moving only their fins and not their body

10. Used for
Bursts of
speed
Constant
Use
muscle

11. Feeding
Fish can be either carnivorous or herbivorous (mostly carnivorous)
The teeth will tell you what they eat
Used for grasping and holding the prey
Prey is usually swallowed whole
Usually have one preferred food source
A type of fish, anemone, urchin etc
Fish that feed on algae are called grazers

12. Digestion Very similar to our digestion
Food passes through the mouth to the stomach
In the stomach food is turned into the basic chemical forms
The chemicals are then absorbed in the intestines
Accessory organs create digestive juices that aide in digestion

14. Circulatory System All fish have a two chamber heart
Simpler than ours with one direction flow

15. Respiratory System
Respiration is done through the gills of the fish
Water is taken in through the mouth – passed over the gills and into the water
Gills are supported by gill arches which hold the gill open
The gills contain capillaries
Thin walled blood vessels that allow the diffusion of gases
O2 is higher in the water so it diffuses into the capillaries
CO2 is higher in the fish so it diffuses out of the fish
To increase the efficiency of the gill the blood flows in the opposite direction of the water in the gills

17. Osmotic Regulation Marine fish osmoregulate to prevent dehydration
Fish replenish lost water by swallowing salt water
Some salts pass out of the body
Some salts are excreted by the kidney

18. Nervous System Most fish have a complex sense of smell
Used to detect prey, mates and predators
Smell is detected in the nares (nostrils)
Fish also have taste buds
Found in the mouth, fins and skin
Catfish have taste buds on barbels (whiskers)
Rely on vision
Eyes focus by moving closer or further from the object they wish to view
Covered by a nictitating membrane – clear membrane that allows the fish to see while protecting the eye

20. Nervous System
Fish use a lateral line to detect vibrations in the water
Lined with clusters of sensory cells
Allows fish to detect predators and prey
Helps them to orient themselves with the current
Helps them school
Fish can detect sound using ears like ours

22. Behavior Territoriality
An established area that the fish protects against invaders
Some are only territorial during mating period others are for life
Thought this helps ensure there is enough food for the fish
Defended by aggressive behavior like making themselves appear larger or by chasing other fish
Fights are rare

23. Behavior Schooling 4000 fish school at some point in their lives
Can provide protection against predators
Can cause confusion
Less likely to be the one eaten if there are thousands of other fish around you
Can increase swimming efficiency by reducing the drag of the water
Can be advantageous for mating or feeding

25. Reproduction Separate individuals for each sex External fertilization
Production of gametes (sperm and eggs) occurs only at specific times of year
Ensures that the eggs and sperm will be released together
Controlled by length of day, moon light and water temperature
Called spawning
Some fish have the ability to change sex if needed
Young develop in eggs laid outside the mothers body and the care given depends on the species