The plant-like giant kelp (Nereocystis spp.) that grow in the Pacific Ocean along the coast of North America can grow ten inches in a single day, reaching over 100 feet tall after one year. They aren’t held up from below, like trees. Instead, gas-filled chambers constructed by the kelp keep them upright from above, like birthday balloons tied to a picnic table. These massive seaweeds reach from the ocean floor to the water’s surface,where their 13 foot-long blades wave in slow-motion across the water’s surface, collecting sunlight.
Learn how I grip with my "holdfast".
Somehow, these amazing creatures remain anchored to the seafloor despite being battered by ocean currents and waves. How do they do it? To begin with, the long stem or “stipe” of giant kelp can stretch to nearly 1.5 times its normal length, like a 4 foot kid stretching to 6 feet tall in the breeze!
Also, at the base of giant kelp, a tangle of root-like growths known as a “holdfast” grab onto the rocky seafloor, anchoring the kelp down. The many branches of the holdfast ensure that if one branch breaks, many more remain to keep the kelp secure.