You can do something like this:
<a href='#' class='arrow closed_arrow'>Click Me</a>
<p>This is the target of the arrow</p>
This starts with the target hidden. If you want to start with it visible, just remove the $("#target").hide();
Obviously, you're going to want to change the "click me" to an arrow using the classes 'open_arrow' and 'closed_arrow' appropriately.
Hope that helps!