Perch Dissection Pre-Lab

1. Perch Dissection Pre-Lab Active Science

2. Dissection Terms • Anterior: situated before or at the front of • Posterior:situated behind or at the rear of • Ventral: situated on or toward the lower, abdominal plane of the body; equivalent to the front, or anterior, in humans. • Dorsal: situated on or toward the upper side of the body, equivalent to the back, or posterior, in humans. • Caudal:of, at, or near the tail or the posterior end of the body.

3. External Perch Anatomy

4. Perch Classification in Domain Eukaryota • Kingdom: Animalia • Phylum: Chordata • Subphylum: Vertebrata • Infraphylum: Gnathostomata • Superclass: Osteichthyes – bony fish • Class: Actinopterygii • Order: Perciformes • Family: Percidae • Genus: Perca • Species: Percaflavescens

5. Perch Facts Yellow perch (Percaflavescens) is a species of perch found in the U.S. and Canada in both fresh and salt water lakes primarily. Recognized by its dark vertical stripes and gold or yellow body color. Size: adults are usually between 4-10 inches (10-25.5 cm) in length. Lifespan: up to 11 years Diet: Adult perch dine primarily on immature insects, larger invertebrates, (crayfish, etc.) and the eggs and young of other fish, which they take both from open water and from the bottom. Spawning occurs at the end of April or beginning of May, depositing 10,000 to 40,000 eggs upon weeds, or the branches of trees or shrubs that have become immersed in the water. After fertilization the eggs hatch in 11 to 27 days depending on temperature and other weather conditions.

6. Perch Anatomy terms • Operculum: a bony flap of skin over their gills that protects the gills and which opens and closes to help bony fish breathe when they are not swimming. • Swim (air) Bladder: a gas filled sac that helps keep bony fish buoyant! • Gills:the organ by which gases are exchanged between the fish and the surrounding water. • Lateral Line: The lateral line is a sense organ in aquatic organisms (chiefly fish), used to detect movement and vibration in the surrounding water.

7. Internal Perch Anatomy

8. How do Gills work in respiration? • The gill works by providing a surface where the water (which has dissolved oxygen) comes into contact with the blood of the fish. • The blood circulation within the gill is arranged in such a way that it flows in opposite direction to the flow of water (=countercurrent arrangement). • Because oxygen will tend to flow (diffuse) from the site of highest concentration to the place of lowest concentration, this arrangement ensures that oxygen will always flow from the water into the blood.

9. Oxygen is not as abundant in water as it is in the air, so for aquatic animals, oxygen concentration is a major limiting factor. The best way to ensure that enough water is "scanned" for oxygen at the gills is providing a really large surface area for gas exchange. Thus, each gill is formed by filaments. Each filament has secondary lamellae that rise perpendicularly to the surface of the filament. The total surface area is extremely large with respect to the volume of the gills. Gas exchange occurs at the secondary lamellae, and it's here where you can see the countercurrent circulation.

10. How does the swim bladder help keep the fish buoyant? • When gas is added to the swim bladder, the fish becomes less dense. • When gas is removed from the swim bladder, the fish becomes more dense. • A swim bladder is filled with air when the fish wants to ascend, and it is deflated when the fish wants to descend.