Disection+of+the+trout

**Objective: ** .- To study the external and internal anatomy of a trout. **Material: ** .- Scissors .- Tweezers .- A trout .- Dissecting tray **Background: ** The trout has a bony skeleton, so it belongs to **the bony fish.** **External Anatomy ** 1.- Place the specimen in a dissection tray. 2.- Note the general regions of the fish: 2.1.- The **head** : Look at the **fish´s mouth:** What are its **teeth** like?_____ What is its **tongue** like? <span style="font-family: 'Times New Roman',serif;">.- At the side of the head, there is a **hard flap** to protect the gills. This is called the **operculum or gill covering.** <span style="font-family: 'Times New Roman',serif;">Used the tweezers to lift up the operculum and look at the **gills. The gills have a lot of __blood vessels__ that allow gas exchange (oxygen and CO2) between the water and the fish.** **<span style="font-family: 'Times New Roman',serif;">.- **<span style="font-family: 'Times New Roman',serif;">What is the colour of the gills? <span style="font-family: 'Times New Roman',serif;">Push a **stick** into the mouth of the fish and observe how the operculum moves. This is what happens when a fish inhales water to breathe. <span style="font-family: 'Times New Roman',serif;">2.2.- The **trunk** region, which terminates at the **anus**. <span style="font-family: 'Times New Roman',serif;">.- What is the body covered with? <span style="font-family: 'Times New Roman',serif;">.- What does the surface of the body feel like? Is it **rough or smooth**? <span style="font-family: 'Times New Roman',serif;">.- Identify the different types of fins: **<span style="font-family: 'Times New Roman',serif;">Dorsal fin ( **<span style="font-family: 'Times New Roman',serif;">has spiny rays),**Pectoral fins,Pelvic fins,Anal fin,Caudal fin** (propulsion mechanism of the animal) <span style="font-family: 'Times New Roman',serif;">.- How many **fins** does the **fish** have in total?_ <span style="font-family: 'Times New Roman',serif;">.- The thin **lateral line** located to the mid-lateral area of the body extends from the operculum to the caudal fin. What does it serve?__ <span style="font-family: 'Times New Roman',serif;">2.3.- **The tail**..- Draw the **caudal fin:** <span style="font-family: 'Times New Roman',serif;">After studying the external anatomy, remove a **scale** from the body and examine it under the microscope. <span style="font-family: 'Times New Roman',serif;">Draw what you observe through the microscope: **<span style="font-family: 'Times New Roman',serif;">Internal anatomy ** <span style="font-family: 'Times New Roman',serif;">.-With the **scissors,** cut a large section out of the body beginning at the posterior edge of the last gill following the lateral line towards the anus. <span style="font-family: 'Times New Roman',serif;">.- Lif out this this large section of flesh and bone and view the following structures: **<span style="font-family: 'Times New Roman',serif;">.- The swim bladder ( a sac of gas). **<span style="font-family: 'Times New Roman',serif;"> In life the air bladder would be inflated but it will likely be collapsed in this specimen <span style="font-family: 'Times New Roman',serif;">.- Dorsal to the air bladder is the dark colored **kidney.** <span style="font-family: 'Times New Roman',serif;">.- The **heart** is near the gills. <span style="font-family: 'Times New Roman',serif;">.- The **liver** is a big gland near the heart. <span style="font-family: 'Times New Roman',serif;">.- The **sexual organs (ovaries or testicles)** are located below the swim bladder.
 * __<span style="font-family: 'Times New Roman',serif;">TROUT DISSECTION __**