Ten Things You May Not Know About Kelp

  1. Kelp and seaweed are actually different. Most people, including us here at Ocean Source, use the words ‘kelp’ and ‘seaweed’ interchangeably in our everyday conversations.  But technically, kelp is a specific subset of seaweed. Broadly speaking, both are actually algae, and can be divided into three groups: red algae, brown algae, and green algae.

Any of these are properly called ‘seaweed’, but ‘kelp’ is only the organisms that belong to a specific subcategory of brown algae—anything in the order Laminariales.  Luckily, “kelp” will often be part of the common name! So bull kelp, giant kelp, and winged kelp are kelps, whereas laver, sea lettuce, and dulse are seaweeds.  And all are delicious—see our Tasting Day post for proof!

  1. Kelp can grow to be up to 200 feet long. The largest species of kelp (in fact, the largest species of seaweed, period) is quite accurately called Giant Kelp, and can be found right off our very own California coast. Ever seen any of the thousands of adorable photos of sea otters floating around the internet? The otters are often in kelp beds, and that kelp is usually Giant Kelp.

Imagine how long each plant must be to reach all the way from the sea floor to the surface! While that’s impressive enough, it doesn’t stop there. Once it reaches the surface, Giant Kelp will keep growing horizontally across the surface of the water, forming huge floating canopies that provide food and shelter for an entire ecosystem.  Almost 800 different species have been recorded as living just in Giant Kelp forests, and of these, over 150 have been found living in the holdfast—the “root” of the kelp, where it attaches to the rocks—alone!

  1. Kelp has incredible health benefits. Many people are calling kelp the next superfood, and with good reason. Kelp has been used for centuries to treat a wide range of maladies, from heart disease to digestive issues. It contains at least 70 different vitamins, minerals, enzymes, etc., as well as antioxidants.

Today, it’s used to help with iodine deficiency and associated problems such as goiter, and can speed the healing time of bone fractures by 20%.  It may also help with obesity by increasing the rate at which the body consumes energy; help with constipation; and a team at U.C. Berkeley found that a diet containing kelp may even help reduce a sex hormone linked to breast cancer!

  1. But the strangest use of kelp might be in the medical field. In obstetrics, a field of study revolving around childbirth and pregnancy, a kelp called Laminaria plays an important role. Like most kelps, Laminaria has a holdfast (roots), blades (the leaflike fronds), and a stipe connecting the two.

However, Laminaria has a thicker and more prominent stipe than many other kelps—it’s harder and thinner, almost like a tree branch! Because of this, it’s often cut out of the plant and dried out to make “laminaria tents”.  These dried laminaria sticks are inserted into the cervix, where, over the course of hours, they slowly reabsorb their water content, causing them to swell.  This swelling dilates the cervix as the sticks expand, which can induce labor or make surgical procedures (abortions, IUDs, etc.) much easier.

  1. Kelp is really, really, really good for the environment. Chris Wilmers of the University of California, Santa Cruz, says that kelp forests are “on par with a tropical rainforest in terms of the amount of carbon they turn over in a year”. Kelp also soaks up the nitrogen that causes “dead zones” in the ocean, helping to undo the acidification that is decimating our seas. This is a big draw of the multi-trophic, vertical ocean farms like the one we’re trying to set up—every plant and animal in there is designed to help clean the ocean.

Sadly, the kelp forests along the California Coast have been under a lot of stress lately and are disappearing at an alarming rate. About 93% of the kelp canopy has disappeared in the last 8 years alone, and the problem is only getting worse.

  1. Kelp may have played an important role in allowing early humans to populate North America. Ancient man first arrived in North America about 15,000 years ago, and the accepted hypothesis is that they followed large game mammals (mastodons, mammoths, etc.) across the Bering Strait and down along the Canadian and eventually California coastline. However, archaeologist Jon Erlandson of the University of Oregon thinks that this might not be the whole story.

His hypothesis, called the Kelp Highway Hypothesis, attempts to supplement the accepted Pacific Coast Migration Model by providing a different incentive. As Dr. Erlandson notes, there was (and still is) an almost continuous “highway” of kelp forests stretching from Japan, up along the Bering Straight, and down the California coast. His theory is that these early travelers weren’t just following big game—they were also moving along these rich and extremely productive kelp highways!

  1. Kelp can grow up to two feet a day. This might seem like a small, oddly specific fact, but really think about it. That’s an entire inch an hour. You can sit and watch it grow. This puts it just behind bamboo (which is capable of growing 3 feet a day) for the fastest growing plant in the world.

This has positive implications for us, of course.  We can harvest kelp (and other seaweeds, many of which also have insanely fast growth rates) much faster than other plants (okay… so kelp isn’t technically a true “plant”) without worrying about overharvesting. Without this high growth rate, we’d have a much tougher time bringing you delicious seaweed snacks and kelp burgers!

  1. Kelp is found in thousands of products that you probably use every day. Kelp has been used in food for millennia, but it’s also used in many surprising commonplace products. Historically, kelp was burned in order to get the ashes (which were also called kelp), as they were primarily sodium carbide. This ash was used in the manufacturing of glass or mixed with animal fats and used as an antiseptic ointment. With the development of photography, the iodine in kelp was extracted to form silver iodide, the light-sensitive compound required to make film.

Today, kelp is used in everything from ice cream, to toothpaste, to salad dressings.  Typically, these products will use alginate, a carbohydrate that is derived from kelp—as a thickener. It serves to provide a creamy texture, but can also be used as a binding agent. In fact, this month, McDonalds is introducing a burger using kelp to hold the meat patty together… much healthier and more sustainable than whatever chemical they were using before!

  1. Kelp reproduces via sperm and eggs, just like humans (kind of). But it’s even stranger than that. Kelp reproduces by releasing spores, called ‘zoospores’, into the water. Zoospores are essentially small packets of reproductive information that “swim” with the help of flagella. For those of you who also haven’t had 7th grade science for a few decades, flagella are those thin, whip-like tails that help some cells swim around. These zoospores can be transported over 200 meters away from their “parent” before attaching to any hard surface they can find.

Once the zoospores settle on a hard substrate, they start producing either eggs or sperm, depending on whether it came from a “male” plant, or a “female” plant, essentially acting as a little gamete factory.  Then these gametes have to find each other in the ocean somehow. Their range is typically only about 1mm…. if the zoospores happen to land that close to one another, the eggs are fertilized and they make a new kelp plant!

  1. Kelp has a place in cultures all over the world. There is evidence of coastal peoples on virtually every continent (darn you, Antartica!) taking advantage of kelp forest resources, and just how important it has been throughout history is evidenced by the sheer number of cultural references to kelp. Kelping is said to be one of the oldest traditional industries around the Ireland coast, and was such a staple in their lives that “the kelp is shining on you” became a well-known idiom implying wealth. In Tonga, they believed that a kelp called Limu Moui would bring them good health and a long life.

Even today, we find kelp references in our own culture where we least expect it.  In the Star Wars universe, kelp has been singled out as one of the only food sources available on the Outer Rim planet of Taris. Since Taris is entirely covered by cities, kelp is their only endemic plant—although most of it died out just before the Taris Civil War when industrialists poisoned the supply.