 by Nan Crowson - Fall 97  The Sargassum weed is a plant that lives in the ocean. Its name comes from the Portuguese word for grapes. It has several grape sized structures that help it to float above the water. The golden-green leaves are saw-toothed and feel almost like plastic. It is a member of the same family as brown algae. Sargassum natans and Sargassum fluitans are two species of Sargassum that are frequently found tangled together. Most of these weeds come from the Sargasso Sea located in the North Atlantic Ocean, and it is about two thirds the size of the United States. Four different currents rotate around the sea creating a wall of cool water that contains the Sargasso Sea. The seaweed reproduces asexually without seeds. Waves break the plant apart, and these parts multiply. These pieces get caught in the currents and are carried to the Gulf of Mexico where the warm waters help the plant to grow rapidly. The Gulf of Mexico is second only to the Sargasso Sea in the quantity of Sargassum weed. The Sargassum weed is something like a floating hotel to a myriad of other organisms. The best way to collect this community is to net a sample using a fine meshed net. Lift the seaweed out of the net and gently shake it. Organisms like small anemones, flatworms, hydroids, pipefish, small crabs, shrimp and Sargassum fish fall out. Most of these animals are similar in color to the goldish green seaweed, and many of their bodies have evolved into forms that also resemble the shape of their host. This camouflage acts as a great aid when hunting food. Many of the Sargassum leaves are covered in a light gray furry substance. These organisms, bryozoans, are a community of many animals that attach to the seaweed. As these animals multiply, they weigh the Sargassum down and begin pulling it towards the ocean bottom. Eventually, this leads to death where it decomposes and serves as food for other organisms. The Sargassum weed is important for the health of the coastal habitat. It provides a place for several animals to hide while they hunt for food. Spadefish and small sea turtles swim near the seaweed looking for an easy meal of shrimp and crabs. As the currents deposit the Sargassum on the beach, humans scoop the smelly seaweed up and put it in piles near the dunes. This can hold the sandy dunes in place long enough for other plants to take root. This action can help new dunes form thus keeping beach erosion at bay. This unique community of plants and animals can adapt and survive in many places. Looking at the seaweed and its partners can also be a source of entertainment and education for people of all ages. More |