Did you know that seaweeds are not plants but rather they are marine algae? Learning this sent me on a quest to gain a better understanding of these organisms.
As is my habit, this means reaching out to expert source materials. In this case, it is two books: The Curious World of Seaweed by Josie Iselin and Seaweeds: edible, available & sustainable by Ole G. Mouritsen. What I’ve learned from these books is summarized here:
Scientists who study seaweeds are known as phycologists. Although, phycologists tend to consider the entire group of freshwater and/or ocean algae. There are very few who solely focus on seaweeds.
Seaweeds have three requirements: access to sunlight for photosynthesis, nutrients for growth, and someplace to attach themselves, which is usually on the ocean floor. (There do seem to be some exceptions to this third requirement, however.) The combination of these three is available in only about 2% of the ocean. Anything deeper than 300 feet is too deep for them to successfully survive.
Each ocean and nearshore or littoral zone has its own types of seaweeds, and some may still be out there to be discovered. There are so many unknowns here to explore.
There is also incredible diversity within the species. For example, some seaweeds are less than 1/4 inch in size, while the giant kelp (Macrocystis pyrifera) can grow to be around 200 feet long.
Seaweeds are generally classified into three main groups: green, red, or brown algae. But don’t be fooled. Its color doesn’t always correlate to its classification. Tissue structure seems to be the predominant determinant of the grouping.
There are many potential uses for seaweeds. Did you know that nearly all seaweeds are edible? (Although, they may not all taste great.) Beyond their use as sushi wrappers, different types of seaweeds can be used in salads, in bread, as snack cakes, and in smoothies. Some types can even be dried and used as a salt substitute.
Other than as food, one of the first technical uses in the early 1800s was to burn kelp (a kind of seaweed) to extract the raw material, soda (sodium carbonate), needed for making glass. In a more contemporary example, today, companies are looking to use seaweeds as a possible biofuel.
Seaweeds also have a lot of value right where they are found. They are food sources for ocean herbivores. They slow shoreline erosion. Additionally, as part of the overall ocean ecosystem, they contribute to the balance of chemistry and create shelter for other species.
I just love looking at them. Some of my favorites include the beautiful red and orange Weeksia reticulata, found in California, Laminaria digitata, also known as Horsetail Kelp, found in Maine, and the Beautiful Fan Weed, Callophyllis laciniata, which is found off the coast of Britain. Look them up. Some are available for sale from collections originating back to Victorian times.