Osteichthyes- Bony fishes

Fish- multiple fish that belong to the same species

Fishes- multiple fish that belong to different species

“Fish” versus “Fishes”

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

Bony Fishes

Two groups: ◦ Lungfish & lobe-

finned fish Characteristics:

◦ Muscular lobes associated with their fins

◦ Have lungs for gas exchange

Infraphylum: VertebrataClass: Sarcopterygii

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

Infraphylum: VertebrataClass: Sarcopterygii

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

Infraphylum: VertebrataClass: Sarcopterygii

Ray-finned fishes Possess swim

bladders◦ Sac filled with gas ◦ Regulates buoyancy

Infraphylum: VertebrataClass: Actinopterygii

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

Infraphylum: VertebrataClass: Actinopterygii

Paddlefish◦ Large, paddlelike

rostrum that detects weak electrical fields

◦ They swim with their mouths open This helps them filter

crustaceans and small fishes

Infraphylum: VertebrataClass: Actinopterygii

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)

Infraphylum: VertebrataClass: Actinopterygii

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

Fish Adaptations

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

Infamous Fish