1. Marine Fish

2. Intro to Fish
Fish
The most common and diverse vertebrates in the ocean
Evolved around 500 million years ago
20,000 different species worldwide (freshwater & marine)

3. Jawless Fish Superclass: Agnatha Lack jaws and paired fins
Cyclostomic toothed mouth used to bore into and suck blood from their victims
Most have a skeleton made of cartilage

4. Examples of Jawless Fish
Sea Lamprey
Eel-like in appearance
Two dorsal fins
Can live in fresh or salt water
Parasitic as adult
Hagfish
Have 3 hearts
Can form an exterior cocoon from slime that they produce
Can go up to 7 months without eating

5. Jawless Fish Feeding

6. Bony Fish 95% of fish Have a skeleton made of bones
Protective covering of scales that are easily removed
Skin secretes mucus to act as a barrier for infection and to reduce friction
Scales indicate approx. age of the fish. Grown in rings called circuli, as fish ages new circuli grow. When they are close together they form bands and the bands tend to represent a year of growth

7. Breathing in Bony Fish
Fish breathe by letting water in through the mouth, passing over the blood-filled gills
Fish also have structures called gill rakers that push food particles into the esophagus, preventing them from entering the gill slits and damaging gill filaments

8. Locomotion in Fish Fish that can swim are known as nekton
Streamlined shape helps fish swim faster
Temperature affects speed
Cold water = slower speed
Nekton as opposed to plankton (which just drift or float on the surface)
Some fins help stabilize fish
Fish sometimes have venomous spines in their dorsal fins (lionfish)
Fusiform shaped fish are tapered at both ends
Fastest fish = sword fish, tuna, dolphin fish (mahi mahi), barracuda
Cold water = lower metabolic rate = slower swimming
Some fish have been able to develop a way to save the heat their muscles generate. This heat keeps metabolism up and can keep moving fast despite cold water.

9. Buoyancy in Fish
Swim bladder: internal gas-filled organ that helps fish stay afloat when they are not swimming
When the bladder gets smaller, the fish sinks
When the bladder enlarges and the fish rises

10. Food-Gathering
Mouth shape & structure depends on feeding method and prey
Straining plankton out of water
Bottom dwellers have vacuum like mouths to suck in food
Beaklike mouths for nibbling on chunks of coral
Strong flat teeth for crushing shells of invertebrates
Predatory fish with large sharp teeth

11. Reproduction in Bony Fish
External fertilization and development
Spawning: the release of gametes during external fertilization

12. Senses Lateral line senses vibrations from water
Detect low-frequency vibrations and directional water flow
Function in distance perception
Fluid-filled canals open to water through tiny pores