Biology 11: Perch Dissection

Perch Dissection

Class Osteichthys

Bony fish - evolved from jawless vertebrates.

Our male perch's anterior end...

Hello Mr. Perch, thanks for teaching us!

External Anatomy

Eye - used for seeing.
Operculum - covers gill slits, water enters through mouth.
Dorsal Fin - provides stability.
Caudal Fin - swimming appendage, used to propel.
Anal Fin - located behind the anus, provides stability.
Pelvic Fin - provides stability.
Pectoral Fin - made of bone, orientation, locomotion, stopping, creates side to side movement.
Lateral Line - subcutaneous canal protruding from the body and head, detects and locates objects and animals.
Scales - small thin hard plates covering a fish's body.

Internal Anatomy

Heart - two chambers: atrium and ventricle.
Mouth
Gills - feathery layers, used for respiration.
Pharynx
Esophagus - leads to the stomach.
Stomach - breakdown (mechanical and chemical) begins here, has three pouches called pyloric caeca (secretory and absorptive functions); empties into the duodenum.
Liver - situated anterior to the stomach.
Gall Bladder - drains bile (necessary for digestion of fats) from the liver.
Intestine - forms a loop (constricts and straightens at the end), extends directly to the anus. A perch's intestine is not very long because of it's carnivorous life style.
Anus - end of the digestive tract, excretes waste.
Kidneys – rid body of nitrogenous wast, help fresh water fish retain salts and excrete a copious, dilute urine.
Swim Bladder - makes the fish buoyant, as a result the fish can remain stationary without moving it's fins.

Respiratory System - Each gill filament is made of lamallae (small, thin wall folds) which contain the gill capillaries. This is where the exchange of oxygen and CO2 between water and blood occurs. Water is constantly being passed over a perch's gills, and is drawn into the mouth and pharynx while the opercula are closed. Valves in the mouth close and the water is forced past through the gills over the gill filaments where the exchange of oxygen and CO2 occurs. This is a counter current system which is an extremely efficient way to maximize movement of oxygen into the blood.

Digesetive System - carnivores.