Fish Class Osteichthyes (Exam 5)

Question 1

Class Osteichthyes

Answer 1

bony fish
salmon, catfish, halibut, marlin
29000 species

Question 2

size

Answer 2

dwarf pygmy goby: 1.5 cm
ocean sunfish: 11 ft/ 5000lbs
arapaima: 9 ft/ 450lbs

Question 3

endoskeleton

Answer 3

bone and cartilage

head and pectoral girdle covered with large dermal bines

Question 4

skin

Answer 4

dermal scales (smooth and overlapping); covered with mucous

Question 5

ectothermic

Answer 5

internal body temperature is determined by external environment (cold blooded) = slow metabolism; some fast swimming fish (tuna) may be more endothermic because of their high metabolism

Question 6

operculum

Answer 6

a hard bony flap that covers and protects the gills; allows fish to breathe without swimming

Question 7

respiration

Answer 7

the operculum opens as the mouth closes, causing a pressure gradient, in which water flows in the direction of lower pressure across the gills, allowing oxygen to be absorbed from the water. this allows the fish to breathe without swimming

Question 8

swim bladder

Answer 8

buoyancy control (gas filled bladder): the combination of gases in the bladder varies (oxygen, nitrogen, carbon dioxide): in shallow water fish the ratio approximates that of the atmosphere, while deep sea fish tend to have a higher percentage of oxygen

Question 9

2-chambered heart

Answer 9

-closed circulation

Question 10

icefish

Answer 10

• 2-chambered heart
• Channichthyidae
• blood contains no hemoglobin; oxygen is dissolved from plasma = low metabolic rates, larger heart, greater cardiac output and blood volume.

Question 11

vision

Answer 11

well developed, able to see in color (large diversity of color in fishes)

Question 12

electric current

Answer 12

ex) electric eel, ray and catfish
- eel is capable of generating electric shocks up to 860 volts, used for prey capture, defense and communication; current produced by the Hunters and Sachs organs allowing the eel to generate both low and high voltage; organs are composed of stacked electroplaques, lined up so a current of ions can flow through them = brain sends signal to electrolytes which opens sodium channels allowing sodium to flow through reversing the polarity = a sudden difference in electrical potential = generation of electrical current (similar to a battery): both organs are involved with electrolocation

Question 13

reproduction

Answer 13

sexual 1) ovoviviparous- live young 2) oviparous- eggs (also hermaphroditic- both male and female reproductive structures)

Question 14

osmotic balance

Answer 14

water/salt balance: 90% of bony fish are restricted to either a freshwater or marine habitat while 10% can survive in both a) estuary: flounder/sculpin b) rivers/streams: salmon: migration-spawn