Ch. 39 - Fish

1. Ch. 39 - Fish • How many of you have a fish aquarium? • What are some types of fish? • What makes a fish different from other animals that we have talked about? • Vertebrates • What phylum do vertebrates belong to? • Chordata

2. Classification of Vertebrates • Kingdom: Animalia • Phylum: Chordata • Subphylum: vertebrata • All chordates at some stage develop 3 things. • 1. Notochord – dorsal rod of specialized cells. • 2. Dorsal nerve cord- hollow tube just above the notochord. • 3. Pharyngeal pouches – small outpockets of the anterior gut. • Most have a post anal tail

3. 3 Classes of fish • 1. Agnatha – means “jawless” • Lampreys & hagfish • Both have a notochord their whole life. • Lamprey are mainly freshwater • Hagfish are marine • Hagfish have a toothed tongue that saws a hole in its prey • Pg. 815

4. Chondrichthyes (class) #2 • Sharks, rays, & skates • Movable jaws; unlike agnatha • Placoid scales – tooth-like spines on their skin. • Pg. 817

5. Shark Characteristics • Very fast side-to-side swimming motion • Have 6-20 rows of teeth pointing backwards. Why? • Can use more than 20,000 teeth in its lifetime. • They have 2 pectoral fins just behind their head that act like wings. They compensate for the thrust of the tail fin.

6. Rays & Skates • Rays have more of a disk-shaped body • Skates have a triangular-shaped body • Both have flattened bodies • Both have great camouflage and hide well in the sand. • Sting rays have a very powerful sting.

7. Osteichthyes (class) #3 • 3 types of bony fish (pg. 822) • 1. Lobe-finned fish (PG. 821) • For over 70 million years scientists thought this fish was extinct until 1938 a South American fisherman caught one. • 2. Lungfish • Can live out of water for long periods of time. (pg.821) • 3. Ray-finned fish • Have fins supported by bones(rays). Most fish are this type. Examples?

8. External Anatomy of a Fish • Yellow Perch  Perca flavescens • Operculum – hard covering that protects the gills on each side. • Caudal fin – tail fin (thrust) • 2 Dorsal fins • 1 Anal fin • 2 Pectoral & Pelvic fins • Helps steer, brake, & move up and down.

9. Integument – skin • Scales that overlap like shingles • Contain chromatophores, which are cells that allow the fish to change colors. • Lateral line – senses vibrations (no ear)

10. Internal Anatomy of a Fish • Food Passage: • Pharynx  Esophagus  Stomach  Pyloric ceca (intestine) • The pyloric ceca are outpockets of the stomach, that have lots of villi that line it.

11. Circulatory System • 2-chambered heart • Atrium – collecting chamber • Ventricle – pumping chamber • The blood is pumped through arteries to small capillaries in the gills for has exchange. The blood then returns to the heart through veins.

12. Respiratory System • Gills with a large surface area • Swim bladder allows the fish to adjust its density so it can float without using much energy.

13. Nervous System • 5 lobes of the brain • 1. Optic lobes – the largest lobes, for sight. • 2.Olfactory lobes – smell • 3. Cerebrum – intelligence • 4. Cerebellum – balance • 5. Medulla oblongata – regulates interior organs.

14. Reproductive System • Separate sexes • 1. External Fertilization – occurs when the eggs are fertilized outside the female’s body. • Ex. Salmon, trout, perch, (most species) • 2. Internal Fertilization – occurs when the eggs are fertilized inside the body. • Ex. Guppies, swordtails, mollies

15. Spawning is the release of the eggs. • Milting is the release of sperm. • What is one way fishes protect each other? • Schools of fish • What is the age limit on a fishing license? • 16 -65