FISH ANATOMY LAB G.R. Smith and K.E Wehrly, Oct. 1995

1) External Anatomy

Quickly identify the following landmarks:

a) upper and lower jaws, eyes, nostrils; opercles (gill cover), isthmus (throat), cleithrum (shoulder); dorsal, anal, caudal pectoral, and pelvic fins; urogenital opening.

b) lateral lines of the mandible, preopercle (cheek), lacrimal, suborbitals, and postorbitals (front, below and back of eye), top of the head, and lateral line scales on sides.

2) Orobranchial chamber (mouth and pharynx):

Make a cut from the ventral point of the right gill cleft forward through the isthmus and sever the left and right mandibles. Pull the opercle, suspensorium, cheek, and right jaws upward and tear the right side off the fish's head (save it).

Examine and sketch the mouth, tongue, gill arches, gill rakers, and gill filaments.

Pull the gill arches out and examine the pharyngeal arches and teeth (the modified 5th gill arches).

3) Body cavity and digestive system:

Make a cut the body wall from the urogenital opening to the branchial chamber.

Examine and sketch the position of the liver, stomach, intestines, swimbladder, gonads, kidneys, urinary bladder (and the spleen and gall bladder if you can find them).

4) Brain and cranial nerves:

Examine the construction of an osteological preparation of the fish skull, noting the bones mentioned in #1.

Carefully break off the skull roof of your dissection specimen and examine the brain. Identify (front to back): 2 olfactory lobes, 2 optic lobes, 1 cerebellum, and 1 medulla. Notice the 10 cranial nerves and the areas they serve.

5) Muscles for feeding:

Remove the skin from the left cheek and jaw bones. Examine and sketch the muscles and ligaments that move the jaw bones. Note the connections and mode of action of the upper lower jaws.

6) Locomotor muscles:

Cut several cross sections through the body and expose the vertebrae and the large epaxial and hypaxial white muscle masses. Note red muscle strips along the sides.

Break apart some of the epaxial muscle cones and trace their connections from vertebrae to skin, to see how they work.

Remove the skin from the base of the caudal fin to expose the muscles and bones--see how the power and intricate control of individual caudal fin rays is achieved.

7) Compare the anatomy of different species dissected by others.