Are you wondering how a floppy kelp plant grows toward the surface? Why doesn't it snake along the seafloor or pile up in a heap?

These are good questions.

At the bottom of each kelp blade, where it attaches to the stipe, there is a bulb-shaped bladder. This bladder is hollow.

If you wanted to help kelp float, what would you put in this bladder?

Try the experiment on the next page!