1. Ichthyes:
The Fish

2. What is a Fish?
Aquatic vertebrate, usually with paired fins, scales and gills.
-fins for movement
-scales for protection
-gills for respiration
-Very diverse group composed of many classes of fish. -

3. Evolution of Fish -Fish were the first vertebrates
-Two important developments :
- jaws
- paired fins
The First Fish
-Strange, jawless animals with bone armour.
-Lived 500 million years ago and didn’t
change for 100 million years

4. The Age of Fish -400 million years ago
-large adaptive radiation created new types of fish
-the new fish species spread around the world
-all were jawless
-both soft-skinned and armoured fish appeared

5. The Arrival Of
Jaws
and Paired Fins

6. Jaws Paired Fins -allowed fish to eat new types of food
-gave them protection
Paired Fins
-paired pectoral and pelvic fins
-fins attached to girdles, b0ne structures in the body
-fish could now swim quickly, hunt and protect themselves

7. ModernFish Agnatha: jawless fish Chondrichthyes: cartilage fish
Osteichthyes: Bony fish

8. Feeding Respiration every mode of feeding
Some will eat anything, others are very specialized
Food:
Enters mouth
Into esophagus
Stomach
Broken down further in the Pyloric Seca
Intestine
Anus
Respiration
Most fish move water over their gills and take out the oxygen
Most fish have a single gill opening protected by the operculum
Lungfish have organs like lungs and can breathe air

10. Circulation Excretion Response
Closed circulatory system (blood is in vessels)
A heart moves the blood in a loop around the body: heart-gills-body-heart
Complex, four-chambered heart
Excretion
-Waste is removed in the form of ammonia
Kidneys help fish control the water in their bodies
Response
-Well-developed brain with different parts
-Most fish have good sense organs
-Lateral Line System lets fish feel movement in the water

11. Movement: -muscles bend their bodies in a S-shaped movements
-fish move forward
-fins stabilize and steer
-body is streamlined
-many fish have a swim bladder to help them float

12. Reproduction -can be either internal or external fertilization
-fish that hatch from eggs are oviparous
Fish that are born alive are:
Ovoviviparous (embryos inside eggs)
Viviparous (embryos connected to the mother)