2.  Fish- multiple fish that belong to the same species  Fishes- multiple fish that belong to different species

3.  All have… ◦ At least one bone in their skeleton ◦ Scales ◦ Gill cover (operculum) ◦ Lung or swim bladder  >24,000 species  Major life form in most aquatic environments  Showed up in the fossil record around 405 mya

4.  Two groups: ◦ Lungfish & lobe- finned fish  Characteristics: ◦ Muscular lobes associated with their fins ◦ Have lungs for gas exchange

5.  Lungfish Adaptation: ◦ Breathe air when lakes and rivers dry up ◦ Burrow into the mud once the water is gone (called aestivation) ◦ Keep a narrow air pathway by bubbling air to the surface ◦ May remain in this state for 6 months or more

6.  Lobe-finned fish (coelacanth) ◦ Thought to be extinct until 1938  One was caught off the coast of South Africa  Fossils date back to over 400 mya ◦ Considered to be a “living fossil” ◦ Large fish (~80kg) ◦ The scales of coelacanths are heavy

7.  Ray-finned fishes  Possess swim bladders ◦ Sac filled with gas ◦ Regulates buoyancy

8.  Sturgeons ◦ Live in the sea & migrate to rivers to breed ◦ Their dorsal surface is covered in heavy scales called “scutes” ◦ Many species are endangered due to overfishing for eggs (caviar)  Beluga caviar is extracted from sturgeons

9.  Paddlefish ◦ Large, paddlelike rostrum that detects weak electrical fields ◦ They swim with their mouths open  This helps them filter crustaceans and small fishes

10.  Teleosts ◦ Modern bony fish ◦ Highly efficient respiratory system ◦ Lateral-line system  Detects low-pressure waves and electroreception ◦ Efficient reproductive mechanisms (they make a lot of offspring)

11.  Locomotion (with fins)- streamlined shape allows for easier & faster movement  Diet- mostly predators  Circulation- two chambered heart to separate oxygenated & deoxygenated blood  Gas exchange- filter water with gills

12.  Candiru- ◦ Lives in the Amazon rivers ◦ Known for swimming up urethras  Angler fish ◦ Lives in the deep ocean ◦ Uses bioluminescence on a lure to attract prey  Light is a result of a symbiotic relationship with bacteria