This is the old technique to holding base. The spiders would sit on the left and right sides of entrance and shoot across while the sharks mined lower entrance. In a serious base game this probably won’t keep the enemy out very long. However, if done right it may work.

This is the new way of doing things. Everyone is positioned at the top of the entrance. The sharks rep, while the spiders shoot down the entrance. You would think this would be a bad idea, everyone huddled into one small area, but if the sharks time well and the spiders shoot it works very well.