Nature’s Pool Floaty
It’s been miserably hot this summer. We could all do with a pleasant holiday to the breezy seaside, where we can snooze on the soft sand in the shade of a beach umbrella or float on the tide with a cool drink in hand. And while we’re all floating there refreshed and perfectly tanned, maybe we can spy some interesting biology floating nearby . . .
Seaweed is a common sight along shorelines. There are three general categories of seaweeds, green (Chlorophyta), red (Rhodophyta) and brown (Phaeophyceae). All three groups of seaweed generate their own energy from the sun using photosynthesis. Green and red seaweeds are distant relatives to land plants, but brown seaweeds are more related to single-celled organisms called protists.
Unlike other protists, brown seaweeds often have multiple cells and can grow to impressive sizes. Think of the giant kelp forests eerily swaying in the Atlantic Ocean. One filament of giant kelp can grow over 100 feet in length! An impressive feature of these brown seaweeds is their ability to float upright under water. They do this through the formation of air bladders, also known as pneumatocysts. Giant kelp relies on multiple bladders to keep their fronds upright, and some brown seaweeds, like bladder wrack (Fucus vesiculosus), are so covered in bladders they look like nature’s bubble wrap.
These tough, hollow structures contain gasses captured from the surrounding water, as well as generated though photosynthesis. The bladders keep brown seaweeds buoyant in the ocean and stretch them out towards to surface of the water. This helps the seaweed capture more sunlight filtering through the murky depths. What’s more, these bladders are pressurized to resist collapsing under the weight of water pressing down on them.
So as you drift peacefully on your inner tube, humbly consider that for all of mankind’s inventiveness and creativity, nature still beat us to the pool floaty.
Brian Rutter, PhD, is the cofounder of Thing in a Pot Productions and plant biologist working for the 2Blades Foundation at the University of Minnesota. Subscribe to our newsletter to receive our “Things About Things – Odd Facts About Plants” and video production tips in your inbox every month!
Works Cited:
Brackenbury, Angela M., Eun-Ju Kang, and David J. Garbary. "Air pressure regulation in air bladders of Ascophyllum nodosum (Fucales, Phaeophyceae)." Algae 21, no. 2 (2006): 245-251.
Damant, G. C. C. "Storage of oxygen in the bladders of the seaweed Ascophyllum nodosum and their adaptation to hydrostatic pressure." Journal of Experimental Biology 14, no. 2 (1937): 198-209.
Mouristen, O. “The Science of Seaweeds.” American Scientist 101, no, 6 (2013): 458.
Popper, Zoë A., Gurvan Michel, Cécile Hervé, David S. Domozych, William GT Willats, Maria G. Tuohy, Bernard Kloareg, and Dagmar B. Stengel. "Evolution and diversity of plant cell walls: from algae to flowering plants." Annual review of plant biology 62 (2011): 567-590.