Prepare cake using two 9-inch round cake pans. Cool.
Prepare the gelatin according to package directions. It works best if it is just a little on the soft side.
On a foil-covered cookie-sheet, place one cake layer for the body. Cut a smaller circle out of the center of the layer. Place this smaller round of cake as the spider's head. Fill the hole left in the body layer with gelatin. Place the other cake layer on top of the body and trim cake slightly to shape , if desired.
To prepare frosting, in a mixing bowl, add blue food coloring to the chocolate frosting until black in color. Frost the entire cake black. Cut the black licorice whips in half and insert for the eight legs. Position the gumballs as eyes.