How is seaweed different from plants

Are categorized as vascular, with a network of xylem and phloem that transport nutrients and dissolved gases throughout the plant.

Use diffusion to extract nutrients from the water. Not plants or animals, but protists. Evolved from terrestrial plants and have tissues that are specialized for certain tasks. Who can describe what seaweed looks like? How do you recognize seaweed when you see it? What are the differences between seaweeds and land plants? Ask youth to spend ten minutes drawing a picture of a seaweed. As they draw, walk around and ask the youth to discuss the following things with their neighbor: Where does your seaweed live?

What color is your seaweed? Describe the shape of your seaweed. How does your seaweed stay attached to the shore? Or does it float free? What makes your seaweed different from a plant on land? What else should we know about your seaweed? After approximately ten minutes, tell the youth to finish up their drawings and ask for two to three volunteers to describe their seaweeds out loud to the group. Everyone should listen carefully as the volunteers describe their seaweed to us.

Explain that they will now explore the different types of seaweed that are common on the Coast of Maine. Explain Ask each group to share the criteria they used to categorize their seaweed. Listen carefully as we hear from each group. After each group shares, explain that scientists categorize seaweed in many different ways, and one of the easiest ways is sorting by color. What color seaweeds do we have in these samples from the coast of Maine?

The youth should be able to identify the three major colors: red, brown and green. Explain to the youth that there are important parts of each seaweed that make them very different from plants on land. Point to the part of your seaweed that looks most like a leaf. You may have to point out the holdfasts in the next part of the activity. Point to a part of your seaweed that allows it to stay afloat. These are air-filled bladders called floats.

Not all seaweeds have floats. Why do you think these seaweed structures have different names than the structures of land plants? Explore Divide the group into five cooperative learning groups. Pass out two portable microscopes to each group. Scientists often use microscopes to get a closer look at seaweeds when identifying them. Aid the youth in using the microscopes. They can practice by looking at the table, their hands, a piece of paper, etc.

Once everyone has been introduced to the microscopes, pass out Pressed Seaweed Samples to each group. These are samples of real seaweeds that have been collected by researchers at the University of Maine. They have been preserved by being pressed and dried, similar to how leaves can be pressed and dried.

Encourage the youth to explore the different seaweed specimens in front of them using their microscopes. Walk around to each group and ask them to separate their samples into two or more categories based on any criteria of their choosing.

Each category must share a similar characteristic. Which of these samples would you group together based on similarities? What makes the samples similar to each other? What makes the groups different from each other? Elaborate Now that the youth are familiar with the three major colors and the parts of a seaweed, they will work in groups to identify the names of their seaweeds using the Gulf of Maine Seaweed Guide.

Pass out a Gulf of Maine Seaweed Guide to each group. Have youth record all observations in their Seaweed Journals.

Draw a picture of your seaweed in your journal as you would if you were a scientist in the field. Can you identify the common and scientific name of your seaweed? What color is this seaweed? What is this seaweed used for? Where does this seaweed live? What is your favorite thing about this seaweed? Each group will then introduce their seaweed species to everyone else. All live at great depth, usually more than 80 metres below the surface. But even though it looked superficially like many green algae, the seaweed turned out to be only very distantly related to any other macroscopic green algae or land plant 2.

At this point, the scientists could do little more than show that the species was very different. With more genes in hand, the scientists could better compare Palmophyllales to an ever-growing collection of green algae. It also allowed the researchers to use phylogenetic software to pinpoint when Palmophyllales branched off from related plant species. It turns out that the group diverged from the rest just after the green plants themselves split into their two main lineages, back when such plants were newfangled upstarts.

Brent Mishler, a botanist at the University of California, Berkeley, finds the new work to be convincing. This paper makes a huge contribution to unravelling how this enormous and important lineage got started. But although Palmophyllales split off early from other plants, its macroscopic size might not have developed until later in its evolution. Still, he says, the whole plant has a distinct structure that includes a root-like holdfast, a stem, and blades. How the cells of the plant communicate with one another remains unknown.

For Charles Delwiche, a molecular systematist at the University of Maryland in College Park, and one of the principal investigators of the Assembling the Green Algal Tree of Life project that supported the work, the result shows how little is known about green algae, despite the fact that they gave rise to all land plants.

Leliaert, F. Bioessays 33 , The primary mineral components in seaweeds are iodine, calcium, phosphorous, magnesium, iron, sodium, potassium, and chlorine. Added to these are many important trace elements such as zinc, copper, manganese, selenium, molybdenum, and chromium. The mineral composition, especially, varies significantly from one seaweed species to another. Konbu contains more than —1, times as much iodine as nori. On average, dulse—a widely eaten red seaweed—is the poorest choice in terms of mineral and vitamin content but, on the other hand, it is far richer in potassium salts than in sodium salts.

In general, marine algae are a much better source of iron than foods such as spinach and egg yolks. Seaweeds contain iodine, although the exact quantities again vary greatly by species.

The iodine content is dependent on where the seaweed grew and how it has been handled after harvest. Furthermore, the iodine is not evenly distributed, being most abundant in the growing parts and least plentiful in the blades. In particular, the brown seaweeds contain large amounts of iodine. It is not known for certain why brown seaweeds contain so much iodine, but this is probably linked to their capacity for rapid growth.

Iodide was found to act as the main antioxidant for this tissue. In addition, the study showed that the action of iodide was not accompanied by an accumulation of organically bound iodine.

The history of the discovery of iodine as an element actually begins with seaweeds. He noticed that his chemical experiments with the seaweed ash gave rise to a violet-colored vapor that condensed as crystals on his copper vessels and, unfortunately, caused them to corrode.

Courtois convinced first his French, and later his English, fellow chemists that his discovery had important dimensions. Their work then rapidly led to the identification of the substance that was the source of the vapors.

It turned out to be a previously unknown element and, as the color violet is called iodes in Greek, the new element was given the name iodine. Terrestrial plants are a poor source of iodine, which can result in iodine deficiency in vegetarians and vegans. The accidental discovery of iodine in seaweeds is a wonderful example of how research and an open mind on the part of the researcher can lead to results that have a major significance for the economy and for human health.

Despite their importance to human diet, seaweeds have often been regarded with disdain. That unpleasant smell is due to a number of gases that are not dangerous, but are the source of odors that we consider offensive. In a bowl mix together the oats, seeds, seaweeds, salt, and baking powder. Add water and mix well until the dough becomes sticky. Divide the dough into two and place one part on a piece of baking paper. On top of the dough add another piece of baking paper and roll the dough out as thinly as possible between the two.

With a knife or pizza wheel cut the top baking paper and divide the dough into squares without cutting through the bottom paper. Remove the top baking paper and place the dough and the bottom paper on a baking sheet. Repeat the procedure with the other part of the dough. After cooling a few minutes, the crispbread can be broken along the scored lines.

One of the chief culprits is a chemical substance, dimethylsulfoniopropionate DMSP , which is found in red and green algae, where it helps regulate the osmotic balance of the cell in relation to the surrounding salt water. Some researchers think that DMSP is an important antioxidant, which provides support for the physiological functions of the algae.

DMSP accumulates in those animals in the food chain that feed on seaweeds. It is formed when DMSP is oxidized in the atmosphere or when it is degraded by bacterial action. It can also be released in the course of food preparation when fresh fish and shellfish are heated. When DMS is released into the atmosphere, it, in turn, is oxidized to form particulate aerosol substances. These can cause condensation of water vapor, which brings about cloud formation and thereby affects the weather.

When brown algae and some types of red algae decay, they can cause the formation of another sulfurous gas, methyl mercaptan. This is the gas that smells like rotten cabbage and is often added to natural gas in order to alert us to its presence. Conversely, fresh seaweeds, much like a delightfully aromatic ocean breeze, have a characteristic, agreeable smell. In both cases this is due to substances called bromophenols, which the seaweeds synthesize. They are released into the air and accumulate in ocean-dwelling fish and shellfish through their food intake.

Because there are no bromophenols in fresh water, fish that live in lakes and streams lack the same pleasant odor and taste as their saltwater cousins. That is yet one more way that seaweeds contribute agreeably and meaningfully to the human diet. Mouritsen, published by the University of Chicago Press. All rights reserved. Skip to main content. Login Register. The Science of Seaweeds By Ole Mouritsen Marine macroalgae benefit people culturally, industrially, nutritionally, and ecologically.

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