Fish…our friends in the water Porcupine Fish Great White Shark

Characteristics of Fish 20,000 species Found in all types of water i.e: Fresh, salt, sunless, polluted, warm, cold, etc. Ectothermic External features Paired fins Scales (protection)

Respiration Respire using gills H 2 O enters mouth. Water passes over gills Water then passes out slits on side of fish O 2 and CO 2 are exchanged through capillaries (small blood vessels) in gills

Circulation Two-chambered heart 1-chamber received deoxygenated blood 2 nd -chamber pumps blood to gills. Oxygen picked up and dispersed to rest of body Carbon dioxide is released Slow process

Nervous/Reproductive System Lateral line---mechanism that detects movements and vibrations. Some fish can smell Two sexes (male and female) External fertilization

3 Sub - Classes of Fish Jawless (Agnatha) Cartilaginous (Chondrichthyes) Bony (Osteichthyes)

Jawless Fish Sharp teeth used to “drill” hole in animal Blood sucked out of hole Endoskeleton made of cartilage Examples: Lamprey, hagfish

Cartilaginous Fish Endoskeleton made up of cartilage Skilled predators (typically found near floor of water source) Examples: Sharks, rays

Bony Fish Endoskeleton made up of bones Lateral line system (pressure change and swim with no light) Swim bladder (allows fish to float) Scales (reduces friction) Majority of fish Examples: Salmon, Trout, Catfish