Chapt 10 Bony FishesIchthyology

“the study of fish”

Phylum Chordata• Class Actinopterygii

– “modern bony fish”– 25,000 species or ½ of all vertebrate species– So diverse no one characteristic can differentiate

them from sharks, skates, and rays (cartilaginous fish)

• Taxonomy of fishes is concentrated on order or family rather than phylum or class (b/c phylum is too broad)

– Taxonomy of fishes are still changing as new technology and research reveal new characteristics

Phylum Chordata• Class Actinopterygii

– Characteristics• Presence of swim bladder: gas filled

sac; add and remove to adjust buoyancy

• Bones• Bony scales• Fin rays

Coelacanths “primitive fish”• Historic fish that give rise to modern day amphibians• Were thought to be extinct 65 million years ago until

living specimens were discovered in 1938 and as time goes on finding more and more individuals “living fossils”

• Live at depths 150-250 meters• Bony skeleton but vertebrae is almost all cartilage

(like sharks)• Maintain high amount of urea to maintain

homeostasis• Reproduction: ovoviviparous

Ray-finned Fishes

• Most numerous and diverse of ALL vertebrates in ocean

• Characteristic-fins attached to body by fin ray– Webs of skin connected by bony plates

2 major groups

• Subclass Chondrostei– Heterocercal tail– Skeleton made mostly of

cartilage– Ganoid scales– Atlantic Sturgeon

• Subclass Neopterygii– Successful b/c bodies

lighter; jaws stronger– Homocercal tails

• Backbone does not extend into tail

– Cycloid OR Ctenoid scales

• Both are thinner and more flexible than ganoid scales

– Salmon; seahorses

Body Shapes-determined by habitat

• Fusiform (torpedo)- streamlined shape for active swimmers

• Laterally compressed- flattened so can maneuver though corals

• Flattened: bottom-dwellers

• snakelike: burrowing fish

Respiration• Gills: receive oxygen and

remove CO2, and maintain salt balance– Made of gill filaments: blood

flows in opposite direction of incoming H2O

• Water must continuously pass over gills– Meets with blood with lower

O2 and higher CO2• Diffusion moves from where to

where?????

– Fish actually “pump” H2O over gills

Cardiovascular

• Close circulatory system: Heart, veins, arteries– Most complex we’ve seen so far!– 4 chambered heart

• Draw Heart diagram in your notes

Nervous System• Brain, spinal cord, nerves• Senses

– Olfaction: sense of smell: olfactory pits (nostrils)

– Taste: receptors on head, jaws, tongue, mouth and barbels on some fish (catfish)

– Eyes Lack eyelids• Most set on sides of face: each eye see

own independent view.

Reproduction• Vast: species specific

– Change Sex– Female to Male: Blue headed

wrasse can change sex ; also form Harems

– Male to Female: Moray Eels– Seahorses: males carry eggs– French Angelfish: mate for life:

Monogamous– Perch: Spawners separate

sexes: No parental care for young

Polygyny Harem13352685556ed59ahttp://i11.p

Coloration- Write in your notes these examples and how they benefit species