1. CHAPTER 18SECTION 1 NOTES

2. 3 CHARACTERISTICSOF ALL CHORDATES: 1. NOTOCHORD – FLEXIBLE ROD THAT EXTENDS ALONG THE LENGTH OF THE DEVELOPING ORGANISM 2. NERVE CORD – IN MOST CHORDATES, ONE END OF THE NERVE CORD DEVELOPS INTO THE ORGANISM’S BRAIN 3. PHARYNGEAL POUCHES – SLIT-LIKE OPENINGS BETWEEN THE BODY CAVITY AND THE OUTSIDE OF THE BODY

3. VERTEBRATES: 1. LARGEST GROUP OF CHORDATES 2. ENDOSKELETON (INTERNAL SYSTEM OF BONES) * PROTECTS & SUPPORTS INTERNAL ORGANS (INCLUDING THE VERTEBRATE & SKULL)

4. BODY TEMPERATURE: (1) ECTOTHERMS (COLD BLOODED) – MOST VERTEBRATES -HAVE BODY TEMPERATURES THAT CHANGE AS THE SURROUNDING TEMPERATURE CHANGES (2) ENDOTHERMS (WARM BLODDED)-HUMANS -BODY TEMPERATURE DOES NOT CHANGE

5. FISH: *LARGEST GROUP *ECTOTHERMS *HAVE GILLS (GET OXYGEN FROM THE WATER) *FINS – PAIRS OF FAN-LIKE STRUCTURES *MOST HAVE SCALES THAT COVER THEIR SKIN

6. TYPES OF FISH: (1) BONY – 95% OF ALL FISH HAVE BONES -MOST USE EXTERNAL FERTILIZATION TO REPRODUCE -EX…..GOLDFISH, TROUT, BASS (2) JAWLESS & CARTILAGINOUS – SCALELESS -LONG, TUBELIKE BODIES -ENDOSKELETON -ROUND, MUSCULAR STRONG MOUTH WITH A JAW -ACTS LIKE A SUCTION -TOOTHLIKE STRUCTURES JAWLESS EX…..LAMPREY CARTILAGINOUS EX……SHARKS, RAYS -MOVEABLE JAWS MOST ARE PREDATORS