I. What is kelp?

II. How does it grow?

III. Who eats kelp?

IV. Living in the kelp forest (clickable diagram)

V. How is kelp affected by El Niño?

VI. Fun with kelp

Monterey Bay Aquarium Kelp Cam

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University of Southern California Sea Grant Program

Fun with Kelp!

Seaweed Recipes | Seaweed Pressing


The study of marine plants, or seaweeds, attracts students and professional biologists alike. The larger plants of the sea are almost exclusively members of a diversified assemblage known as algae, and their study is known as algology. Some scientists are interested in their physiology (life processes), others work on ecology, distribution reproductive activities. Basic to much of this is the field of taxonomy, or identification and categorization of the many species. All of the other study areas rely on taxonomists to identify the plants upon which they do their observations or experiments.

In order to prepare the plants for examination and identification, there are several standard processes and procedures which must be followed. These methods are similar to those used by professional collectors. The plants are collected, preserved, mounted on special paper and dried. Then they are catalogued for future reference and identification. By using these methods, you may wish to begin a small personal collection, or merely to press some plants for framing or for greeting cards.

Collection and Preservation:

The greatest abundance of marine algae is found in the relatively shallow, sunlit nearshore waters (40 feet or less). They can be observed and collected using scuba or by snorkeling. A number of the more resistant species are in the large piles of seaweed found on the beach after a storm.

Once collected, the plant material may either be mounted and pressed while fresh (almost immediately), or preserved and kept in a suitable container, away from the light, for longer periods of time. The fresh material may retain slightly more color than the preserved, but drying will take longer. It is best to collect specimens in a plastic bag, then transfer them to a container of seawater and formaldehyde mixed in a 19:1 ratio. Small amounts of formaldehyde may be obtained at a drugstore, while large quantities can be ordered from a biological or chemical supply house. If specimens are to be kept some time before mounting, storage is best in a tightly closed metal can or in a glass jar, in the liquid, away from light.

Mounting and Drying

Mounting is easy, but also requires some special materials. The specimens are floated onto a special high quality, acid-free rag paper (herbarium paper) then pressed and dried in a plant press or by using weighted plywood. The addresses of suppliers are listed at the end of this activity.

Materials you will need:

  • several specimens of fresh marine algae
  • shallow baking pan or plastic painter's drip tray or broad enamel pan
  • thin piece of masonite cut to fit the pan
  • heavy white mounting paper--high quality acid-free paper is best (herbarium paper) *Scroll down to see suppliers addresses.
  • newspapers
  • clean fabric to cover masonite
  • corrugated cardboard
  • rope
  • two 12" X 20" pieces of plywood
  • seawater
  • bricks or rocks
  • waxed paper
  • white glue (optional)


  1. A small amount of tap water is placed in a painter's drip tray and a piece of herbarium paper is laid in the bottom.. (If using a baking pan, also place the masonite in the pan and the herbarium paper.)
  2. A fresh or pickled plant is floated in the water and allowed to settle down on the paper.
  3. Place some sheets of newspaper on top of a piece of corrugated cardboard.
  4. After it has been spread out and suitably arranged, the paper and plant are carefully slid out of the tray (and off the masonite, if it has been used), drained momentarily, and laid on the corrugated cardboard that has newspaper on top.
  5. Waxed paper or clean fabric is placed over it, then another newspaper and top with cardboard, and then another paper with its specimen.
  6. Place a piece of newspaper over the cloth and top with another piece of corrugated cardboard. You can stack several different specimens for mounting using this same layering procedure: cardboard, newspaper, mounting paper with specimen, newspaper, cardboard.
  7. Place the finished stack between the two pieces of plywood. Tie together securely with rope and weight down with bricks or rocks. Place near a heater or a warm, open window.
  8. After 24 hours, change the cloth, newspapers, and cardboard. After 48 hours remove the cloth. Change the newspapers and cardboard daily until the specimens are dry to the touch. Delicate plants will take about 48 hours to dry completely; coarse plants may take up to 5 days.
  9. When the pressing is complete, the algae is usually stuck to the paper. If not, use white glue to fasten it permanently to the paper. Do some research about the specimens of algae. Label your specimens with the species name, place and date of collection, collector's name.
  10. Stored flat in albums or in herbarium cabinets.


Unissource West Inc., Carpenter/Offutt Paper, Inc., Div.
Herbarium Dept.
927 Thomas Ave., SW
Renton, WA 98055-2931

Herbarium Supply
705 Bridger Dr, Unit D
Bozeman, MT 59715-2292
Tel: 800.348.2338
Tel: 406.994.0006
Fax: 406.994.9211
Email info@herbariumsupply.com
Website http://www.herbariumsupply.com


University of Southern California Sea Grant Program
3616 Trousdale Parkway - AHF 254
Los Angeles CA 90089-0373
(213) 740-1961