Fish Flashcards
What class are fish in?
Actinopterygii
How many species?
Approximately 40,000 (about 1/2 of all vertebrate species)
What kind of tail do fish have?
Homocercal
What type of scales to fish have?
Usually Ctenoid (D-shaped, rougher surface) or Cycloid (round/smoother)
Can also be ganoid, cosmoid, or scutes
Osmoregulation in fish (fresh vs. salt water)
Saltwater: drinks seawater, salts excreted through gills and gut. Produce small volume of relatively salty urine. Water loss by osmosis through gills and skin.
Freshwater: does not drink, salts absorbed by gills, no salts enter gut. Produce large volume of dilute urine. Water gain by osmosis through gills and skin.
Osmoregulation in sharks vs. fish
Sharks: gills block loss of urea, ingests salts with foods. Most urea retained by kidneys, salts excreted in urine & by rectal gland. Slight water gain by osmosis through gills and skin.
Bony fishes (marine): gains water and salts by swallowing seawater and food. Salts excreted by chloride cells of gills, some salts pass through gut, some salts & water lost via urine. Kidneys retain water. Water loss by osmosis through gills and skin.
Unpaired fins
2 dorsal fins, caudal fin, anal fin
Paired fins
Pectoral fins and pelvic fins
Spiny dorsal
1st dorsal fin. Primarily for maneuvering, stabilization & defense.
Soft dorsal
2nd dorsal fin. Primarily for low speed maneuvering and swimming.
Caudal fin
Tail fin. Used for propulsion.
Anal fin
On ventral (bottom) side, toward back, opposite of soft dorsal. Used for stabilization.
Pectoral fins
Located on sides of body. Used for swimming, maneuvering, and stabilization.
Pelvic fins
On ventral side underneath the pectoral fins, used for stabilization.
Operculum
Gill cover, bony and tough structure
Protects gills and serves as “bellows” to help pump water over gills
Branchiostegal Membrane
Seals operculum and prevents back flow of water into the gill chamber
Nares
external nostrils, used in odor detection (not breathing)
Lateral line
Series of small fluid-filled canals lying just beneath the skin on the head and along the sides of the body (dark colored). System of receptors transforms underwater sound or mechanical disturbance into nerve impulses.
Caudal peduncle
located just before the caudal fin
Function: generates power to the caudal fin for swimming
Stomach
located in middle of body cavity, comes after esophagus and before intestines
function: food storage and digestion
Pyloric caeca
finger-like structure located above/underneath the stomach
function: aid in digestion and absorption
Gall bladder
small, located toward front of body (between stomach/liver)
sac, typically green, that holds bile for enzymatic digestion
Intestine
located after stomach, large, twisty
simple intestines, used for digestion
Pancreas
a diffuse organ, extending over the surface of the intestine and connective tissues/blood vessels. Can only be differentiated by using a microscope.
function: secretion of digestive juices and insulin
