Are Both Jaws of the Fish Equally Movable Updated

Are Both Jaws of the Fish Equally Movable

Perch Dissection

Introduction and Pre-Lab Information:

The fish in the class Osteichthyes have bony skeletons. There are three groups of the bony fish --- ray-finned fish, lobe-finned fish, and the lung fish. The perch is an case of a ray-finned fish. Its fins have spiny rays of cartilage &/or bone to support them. Fins help the perch to motion apace through the water and steer without rolling. The perch also has a streamline body shape that makes it well adapted for motility in the water. All ray-finned fish have a swim float that gives the fish buoyancy allowing them to sink or rising in the h2o. The swim bladder also regulates the concentration of gases in the claret of the fish. Perch have powerful jaws and strong teeth for catching and eating prey. Yellow perch are primarily bottom feeders with a slow deliberate bite. They eat well-nigh anything, but prefer minnows, insect larvae, plankton, and worms. Perch move about in schools, oft numbering in the hundreds.

The scientific proper name for the yellow perch, most often used in dissection, is Perca flavescens (Perca means "dusky"; flavescens means "becoming gold colored"). The sides of the yellow perch are golden yellowish to brassy green with 6 to eight dark vertical saddles and a white to yellow belly. Forth the side of the fish is the lateral line. Click HERE to learn more about the lateral line and its functions. Yellow perch have many small teeth, but no large canines. Yellowish perch spawn from mid-Apr to early May by depositing their eggs over vegetation or the h2o bottom, with no intendance given. The eggs are laid in big gelatinous agglutinative masses.

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Materials:

Preserved perch, dissecting tray, scalpel, scissors, forceps, Brock microscope, dissecting pins, length of string , ruler or meter stick

Process (External Anatomy): Perch Dissection Vide o Part 1

Click HERE to access the Perch Autopsy Manual (will need this to answer the questions on the review)

Obtain a perch & rinse off the backlog preservative. Place the perch in your dissecting pan.
Use your cord and ruler or meter stick to make up one's mind the total length, fork length, and girth of your fish.

Locate the 3 body regions of the perch --- head, body, and tail.
Open the perch'southward oral fissure and detect its bony jaws. The upper jaw is fixed and volition not move. The mandible is the moveable office of its jaw.
Feel the within of the mouth for the teeth.
Fish have three types of mouths. Come across diagram below.
Based on this....what blazon of mouth does the perch have?
Open the mouth wider and utilise a probe to reach back to the gill chamber.
Find the lateral line on the side of your perch.
Find the bony covering on each side of the fish'due south head called the operculum. The opercula cover & protect the gills.

Use a probe to lift the operculum and observe the gills. Note their color.
Use a pair of scissors to cutting away one operculum to view the gills. At that place should exist ii pairs of gills on each side of the perch (4 total gills). Find the gill slits or spaces between the gills. Click Hither to notice more information about gill rakers.
Use your scalpel to carefully cut out one gill. Find the cartilage support chosen the gill curvation and the soft gill filaments that make upwards each gill.

Fish Gill Anatomy

The gill structure on the right is the i that volition exist constitute in your perch.

There are four sets of gills on each side of the perch as seen in the higher up diagram.

Observe the different fins on the perch. Locate the pectoral, dorsal, pelvic, anal, and caudal fins. Note whether the fin has spines.

Locate the anus on the perch anterior to the anal fin. In the female, the anus is in front of the genital pore, and the urinary pore is located backside the genital pore. The male has only one pore (urogenital pore) behind the anus.
Use forceps to remove a few scales from your fish. Observe the scales under the Brock microscope.

Close-upwards View of a Perch Scale

The age of the fish the scale above was taken from is 7 years.

Click Hither for more information about fish scales in general.

Process (Internal Anatomy): Perch Dissection Video Part 2

Use dissecting pins to secure the fish to the dissecting pan. Use scissors to make the cuts through skin and musculus shown below.

Cut Lines for Internal dissection

After making the cuts, carefully lift off the flap of skin and muscle to betrayal the internal organs in the body cavity.
Locate the cream colored liver in the front of the torso cavity. Also locate the gall bladder between the lobes of the liver.
Remove the gall float & liver to observe the short esophagus attached to the stomach.
At the posterior end of the stomach are the coiled intestines.
Notice the small reddish brown spleen near the stomach.
Below the operculum, are the bony gill rakers.
In front of the liver & backside the gill rakers is the pericardial cavity containing the centre. The center of a fish only has two chambers --- an atrium & and a ventricle.
In the upper part of the torso beneath the lateral line is the swim bladder. This sac has a sparse wall and gives the fish buoyancy.
Beneath the swim bladder are the gonads, testes or ovaries. In a female person, these may be filled with eggs.
Detect the 2 long, dark kidneys in the posterior cease of the perch. These filter wastes from the blood.
Wastes exit the body through the vent located on the ventral side of the perch.

Complete the Post-Lab Questions on your Perch Dissection Review Worksheet

Click HERE for the Perch Dissection Lab Companion