1. Dissection 101: Perch Reasons to Use the Dissection Video and
Accompanying PowerPoint Presentation
Reduce the number of specimens used by a class
Increase the quality of the dissection for the students
Review opportunity, increasing the learning experience for the students
Student unable to dissect due to pregnancy or hypersensitivity to the preservatives
Student chooses not to dissect due to ethical/moral reasons
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2. Dissection 101: Perch Click
Safety Considerations
Age appropriate activity for the children in your care
Material Safety Data Sheet (MSDS) available for accident reference
Poison control number/phone readily available
Latex free gloves, eye protection and apron/lab coat
Eyewash station, shower and sink
Sharp instruments (cut away from self and others)
Sharps and specimen(s) disposal
Encourage students to report all accidents
Basic science laboratory rules (strictly enforced)
As an educator you are responsible for the implementation of the dissection activity described in the video and PowerPoint. You must have safety procedures and rules established for your classroom and make sure all of the students follow the rules to ensure a safe environment. South Dakota Public Broadcasting and Dakota State University cannot in any way be responsible or liable for any injury as a result of performing the described dissection. Complete the dissection if you feel it is appropriate and safe for your individual class.
Have fun and stay safe!
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3. Perch Dissection 101: Click
Perch are vertebrates in a group called the “ray finned fishes” because they have rays/spines in their fins. They are the largest group of vertebrates; there's more than 20,000 species of these, which is nearly three times the next largest group of vertebrates.
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4. Dissection 101: Perch Click Perch (fish) characteristics:
Fins – Provide movement forward (propulsion), maneuverability (directional movement), and stabilization
Vertebrate – has backbone (spinal column)
Uses gills for respiration
Lives entire life in water
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5. Exterior of the Perch Click
Dorsal fin (cranial and caudal sections) - Stabilize
Caudal fin -
Movement forward
Graphic: SD Game Fish & Parks
Pectoral fins (paired) -
maneuverability
Anal fin - Stabilize
Pelvic fins (paired) -
maneuverability
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6. Exterior of the Perch Preserved Yellow Perch Click Closeup: Anal fin
Closeup: Caudal fin
Closeup: Paired pectoral & pelvic fins
Your specimen will look similar to the photo above, not the graphic on the preceding page.
(notice the rays/spines)
Closeup: Dorsal fin
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7. Eyes – Paired; does not have eyelids
Exterior of the Perch
Nostrils – Paired; used to sense chemicals in the water; not connected to the throat
Close up:
Extended mouth
Mouth – Specially adapted mouth that extends to form large gape (wide opening); the mouth is then quickly retracted resulting in a suction drawing prey into the mouth
Eyes – Paired; does not have eyelids
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8. Exterior of the Perch Click
Lateral Line – Specialized sensory structure for detecting pressure changes/movement (Ex. vibration (waves) from movement of prey)
Close up:
Operculum and Gills
Operculum - Bony flap that covers and protects the gills; opens and closes to help move (pump) water from the throat, across the gills, and then out the operculum
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9. Exterior of the Perch Click Close up: Cloaca Close up: Scale on probe
Scales - Very thin protective layer, almost transparent; made of bone like material and lie underneath a layer of skin (epidermis)
Cloaca – Common opening for both the
urogenital and digestion systems
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10. Dissection 101: Perch Getting Started
Use water to rinse the excess preservative from your specimen
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11. Dissection 101: Perch 3 4 2 1 Click
Lateral Line
Operculum 3 4 2 1
Always cut away
from yourself
Place the scissors in the cloaca and press upward with lower part of the scissors against the muscle/skin to prevent cutting too deep; 1. cut toward the lateral line until you feel resistance from the upper cavity; 2. cut toward the head until you reach the operculum; 3. cut toward the head until you reach the operculum; 4. cut upward toward the lateral line; carefully remove the flap of muscle/skin to expose the body cavity (example next slide)
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12. Dissection 101: Perch Click
Swim bladder – Large adjustable air-filled sac-like structure that changes the density of bony fish (Osteichthyes) resulting in increased buoyancy (not found in sharks)
The large structure shown above is the female gonad (ovary); depending on the season, the male and female gonads may be very large occupying most of the cavity, compressing other structures
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13. Gonads – Reproductive structures
Dissection 101:
Perch
Female or Male
Things to look for:
Single gonad in female (ovary); paired gonads in male (testes)
The testes have a smooth, glandular appearance The ovary has a granular appearance (many developing eggs)
Female
Ovary
Gonads – Reproductive structures
Ovaries
Developing eggs
Ovary
Female
External Fertilization: Female lays eggs externally; male spreads gametes (sperm) over them; poor survival rate so many eggs and sperm released
Testes
Male
Testis
It is very difficult to distinguish female/male from the exterior of the perch; depending on the reproductive age/season, it may also be difficult to identify male or female internally.
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14. scientifically smaller
Dissection 101:
Perch
Slowly remove the gonad(s) with a probe; single female ovary shown in this example is very large, compressing other structures in the cavity; depending on the age of your specimen and season
the gonad(s) could be
scientifically smaller
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15. Dissection 101: Perch Click
The next two cuts (above) will help expose the structures compressed cranial by the large ovary; also the gills and heart will be visible; be careful not to damage the gills or heart.
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16. Dissection 101:
Perch
Structure identification: Your specimen is unique; many of the structures will not look exactly like the photos or drawings in your book; the following slides will identify structures using multiple views and specimens
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17. Color of a typical liver in a preserved perch
Dissection 101:
Perch
Color of a typical liver in a preserved perch
Liver (green in this specimen) – The liver is large, has a waxy appearance, and is usually white/tan; detoxifies blood and produces bile for fat digestion
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18. Dissection 101: Perch Click
Atrium (thin walled) – Receives deoxidated blood from the body and pumps it into the ventricle
Spleen – Immune (white blood cell production); filters and stores blood
Heart
Ventricle – Muscular structure that pumps blood to the gills for oxygen exchange and then to the rest of the body
Intestine – Digestion of food and absorption of nutrients (small section); movement of undigested waste to the anus (large section)
Pyloric caeca – food storage and digestion
Stomach – Muscular structure that mixes and stores food; food broken down by digestive juices
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19. Dissection 101: Perch Click Liver
Gills: Feather-like structures (increased surface area); used to remove oxygen from water for respiration
Heart
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20. Dissection 101: Perch Click Different Specimen Swim bladder Spleen
Testis
Liver
Gills
Heart
Ruptured Intestine
Intestine
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21. Dissection 101: Perch Click Different Specimen Swim bladder Stomach
Spleen
Ovary
Liver
Intestine
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22. Dissection 101: Perch Click Different Specimen Swim bladder Intestine
Liver
Heart
Pancreas – Enzyme producing structure for digestion; insulin production
Testis
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23. Dissection 101: Perch Produced by Dakota State University
and South Dakota Public Broadcasting
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