Home Fish Index Lecture Notes  Fish List Endangered Species



Some basic instructions:

1. The goal of this lab is to prepare you to be able to identify fish species by their key characteristics, and to learn some natural history about the major groups of fish.  You will be tested on this material in a quiz one week from today.

2. Readings are available in labeled file folders at the side table.  DO NOT remove these folders from the lab.

3. Be gentle with the specimens in the lab.  Always return fish specimens to the jar that you got them from, and DO NOT leave them out to dry – don’t return a specimen to the wrong jar!

4. Perch for dissection are available at the side table.  Share your fish with one or more people, and return the fish to the bucket if it is still useable by another group.



Complete the following exercises.  If the meaning of a term is not clear, consult the glossary at the back of this handout or look it up in the available reference books.  Before starting a study of the various groups of fishes it is necessary to become familiar with the general anatomy of a fish, and with a number of terms and structures that will be encountered in connection with identification work.

1. Superclass Agnatha:  Examine specimens of adult and larval (amnocoetes) sea lamprey (Petromyzon marinus) and any other related types.  Read pages 194-200 in Moyle and Cech.  Study and locate the structural details given in Eddy and Underhill, 26-32.  Skim the identification keys to lampreys and note the important identification characteristics.

2. Structure of bony fishes:  Read pages 6-12 in Eddy and Underhill and pages 11-35 in Bond

    a. Review methods of counting and measuring on Figures 1 and 2 in Eddy and Underhill.

    b. Be able to distinguish between rays and spines.  Carefully examine and draw a spine and a soft ray from the dorsal fine of a yellow perch

    c. Note the spines on the back of the stickleback.  These are known as free spines.  Examine the spine in the pelvic fin of Cottus (sculpin).  Examine the spines in the first dorsal of a Cottus.  These are called soft spines.  Also see spines in
        Ameiurus or Noturus.
    d. Familiarize yourself with the following terms for the position of the mouth.
            i. Inferior in the sucker
            ii. Subterminal in the dace
            iii. Terminal in the trout
            iv. Superior in the killifish 


    e. .  Study the caudal fins in the following specimens giving attention to the relation between the caudal vertebrae and the
        bony elements supporting the tail.
            i. Protocercal tail of sea lamprey
            ii. Heterocercal tail of gar and bowfin
            iii. Homocercal tail of flounder
            iv. Isocercal tail of codfish (Gadus)

    Locate vertebral column, fin rays, and Hypural plate (if present) on each.  The types of tails are listed in order of
    specialization, protocercal being most primitive.

3. Fish scales:
    a. Draw and be able to identify the following:
            i. Ctenoid scale:  rough scales found on a perch.
            ii. Cycloid scales: smooth scales of a sucker.
            iii. Ganoid scales:  on a gar (rhombic arrangement) and of a sturgeon.
            iv. Placoid scale:  on a shark.

    b. Growth annuli:  Remove a scale from the side of a perch.  Examine under a microscope.  Note the layer of epidermis on
        the posterior border.  Draw the outline and details of this scale Remove a lateral line scale from a perch and note the
        position of the pore and the number of growth annuli..

4. Breeding tubercles (pearl organs):  These small pimple-like protrusions are found on the anterior and dorsal surfaces of some minnows and suckers during the spawning season.  They are usually limited to the male.  Note the position of the tubercles on Campostoma (central stoneroller).  What is the function of breeding tubercles (judging from their position)?

5. Gular plate:  Examine the ventral side of the head of a bowfin (Amia), and note the gular plate (between rami of the lower jaws).

6. Note the isthmus (the space between the gill clefts) in the yellow perch.  Are the gill membranes (not the membrane covering the gill filaments) joined to the isthmus in the yellow perch?  In the common sucker?  How many branchiostegals has the yellow perch?  Compare the manner of folding of the branchiostegals in the yellow perch with that of Fundulus.

7. Barbels:  How many barbels can you locate in the bullhead, in the yellow perch, in the river chub?  Sketch the barbels of a fallfish and a long-nosed dace showing the precise location with relation to the premaxillary and maxillary.  Use binocular scope.

8. Lateral line:  What is meant by the lateral line of a fish?  Locate this on the yellow perch.  Trace the continuations of lateral line in the form of pores on the head of the sucker and pike.  How many branches do you find and what is the direction of each?  Draw a dorsal and lateral view showing the continuation of the lateral line on the head of the common sucker.  Observe the lateral line canals on the Chimera.  See references for terminology.

9. Pseudobranchs are small gills developed on the inner side of the gill cover, near its junction with the preopercle.  Examine the pseudobranchiae in the codfish and striped bass.  Are they concealed or exposed.  Can you find them in the perch?

10. Examine the nostrils in the yellow perch, common sucker, bowfin, and sea lamprey.  What variation in position do you note.  How many openings are there in each case?

11. Oral Cavity – Obtain a perch specimen from the bucket at the side table and follow the instructions below.   Please work in pairs or small groups.  Consult pages 40 –42 of the perch anatomy guide (Chaisson and Radke) at the side table as needed.

    a. Expose the oral cavity of the yellow perch by making a slit with the scissors on one side from the corner of the mouth to
        the posterior angle of the operculum.  Identify gill-rakers and gill filaments.  What is the function of each?

    b. Locate the oral breathing valves, just inside the mouth of the yellow perch.  They are folds of membrane just behind the
        more anterior teeth in upper and lower jaws and serve to close the mouth tightly in respiration when water is forced
        backward out of the gill openings.  If available, watch a live fish and observe the manner of breathing.  Describe.

    c. Examine the tooth patches in a yellow perch and compare them with those of a rock bass (see diagram at lab station).
        Draw similar diagrams for the perch showing tooth patches present.

12. Types of teeth  Familiarize yourself with these teeth types.
        a. villiform teeth of a bullhead
        b. cardiform teeth of pike (upper jaw)
        c. canine teeth of pike (lower jaw)
        d. incisor teeth of sheepshead
        e. pavement teeth of ray
        f. coalescent teeth of parrot-fish
        g. large triangular teeth of shark

13. Pelvic fins:  Note the position of the pelvic fins in the yellow perch as contrasted to the common sucker.  They are thoracic in the former, abdominal in the sucker.

14. Weberian apparatus  Certain groups of fish have a Weberian apparatus consisting of four bony elements extending from the skull to the air bladder.  What is the function of the Weberian apparatus?

15. Label the attached diagrams of the body and head structures of a fish.