MUSSEL+DISSECTION




 * Objective: **

.- To study the external and internal anatomy of a mussel.

**Material:**

.- Scissors

.- Mussels (the mussels must be opened with steam the previous night)

.- Dissecting tray

**Background:**

Mussel is a bivalve mollusc. As the term bivalve indicates, these animals have a shell made of two valves, which are similar in shape and size and are hinged on one side.

Most molluscs share the following characteristic:

**.- Head**

**.- Body mass with the main organs**

**.- Muscular foot to move about**

**External anatomy**

Determine the dorsal, ventral, anterior and posterior regions of the animal.

The valves are held together by two strong **adductor muscles** inside the shell.

.- On the outer side of each valve you will observe several lines, they are **growth lines.**

.- On the ventral side observe **the filaments** to attach the animal to a substrate.

.- The **pearl** (nácar) is the bright substance that covers the interior of the shell.

**Internal anatomy**

The animal has a soft body without any segments and without a differentiated head.

As these animals have **bilateral symmetry**, all their organs are located like the pages of a book.

The **mantle**, two lobes that cover the whole body of the animal, the border is black.

By transparency we can observe a greenish organ which contains the **pancreas** and the **live**r.

As you lift the mantle, you will observe on its inner surface a two pleated structure, gray or brown colored, which are the **gills (they are like sheets).**

Locate the **mouth**, surrounded by **four tongue-shaped structures.**

Locate the black **foot** and, next to it, the **filaments gland** and the **gonads**. Gonads are yellowish in females and orange in males.

.- Take a sample of the gills, place it on a slide. Add a cover slip and observe it under the microscope.
 * [[image:mussel.jpg width="800" height="708"]] ||  ||
 * [[image:mussel 2.jpg width="800" height="719"]] ||  ||