Answer the following…• Compare and contrast jawless fish to Cartilaginous fish • Organisms that use external fertilization usually

produce more eggs at one time than organisms that use internal fertilization. What might explain this difference

• A student takes fish A from and saltwater tank and fish B from a freshwater tank. The student then returns each fish to the wrong tank, and the next day both fish are dead. Form a hypothesis that explains why

Bony Fish

Bony Fish Characteristics• There are about 24,000 species of bony fish• There are two types of bony fish – 1. Ray-finned fishes– 2. Lobe-finned fishes

• They are considered one of the most successful vertebrates

• All bony fish have a strong endoskeleton made completely of bone

• A lateral line, opercula, and swim bladders are structural adaptations that have led to their success• A very small number of bony fish have lungs

• Bony fish have scales that cover the body• Scales protect the fish and reduce friction while swimming

Lateral Line

• Bony fish have a fully developed lateral line system

• When water pushes against the fish’s side, nerve impulses from sensory cells in the lateral line go to the brain – This allows the fish to be aware of its position and

rate of movement– It also allows a fish to detect an object by

movement of water deflected by that object

Gill Cover• Most bony fish have an

operculum– An operculum is a hard plate that is

attached to each side of the head, that covers the gills and is open at the rear

• Movements of the opercula and nearby muscles draw water over the gills, which allows the fish to take in oxygen– This allows bony fish to take in

oxygen while remaining in place compared to sharks and other fish that have to move forward to take in oxygen

– The ability to take in oxygen without movement allows bony fish to conserve their energy

Swim Bladder• A bony fish’s body is denser than

the water and would sink without a swim bladder

• By adjusting the fish’s swim bladder gas content bony fish can regulate their buoyancy– As the swim bladder fills with gas

the fish rises– As the swim bladder empties the

fish sinks• Bony fish do not have to keep

swimming to keep from sinking– Bony fish also have highly mobile

paired fins which enable bony fish to turn sharply and paddle backwards and therefore keep them from sinking

Ray-Finned fishes• Most bony fishes are ray-finned

fishes• Their fins are supported by bony

structures called rays• Teleosts are the most advanced

type of ray-finned fish– Teleosts have very mobile fins, thin

scales, and completely symmetrical tails

– 95% of all living fish are Teleosts– Teleosts are so successful because

of their ability to suck food towards their mouth due to its ability to protrude its upper jaw forward in order to grasp food

An example of a Teleost is the perch

Lobe-Finned Fish• Only seven species of lobe-

finned fishes exist today– One species is the

coelacanths and the other six species are lungfishes

• The fins of lobe-finned fish are muscular structures supported by bone– The bones of the fin are

connected by joints– The bony rays of lobe-finned

fish are found only at the tips of the fins and each bony ray can be moved individually by the muscles in the fin

• Lobe-finned fish was the direct ancestor of amphibians and all other land vertebrates

Introduction to the Perch

• Scientific Name: Perca flavens• Size: About 0.3m long and up to 2.3 kg• Range: Found in lakes and rivers from the Great Lakes

to the Alantic coast and as far south as South Carolina• Habitat: Lives concealed among vegetation• Diet: Feeds on insect larvae, crustaceans, and other

fishes• Reproduction: Female perch lay strings of eggs that are

fertilized externally and the young hatch within days

Yellow Perch External Anatomy

Yellow Perch Internal Anatomy