Seaweed
Most of the plants that live in the shallow waters are seaweeds (underwater meadows). They provide shelter, place of reproduction and food for many different sea and animals.
Together with phytoplankton (microscopic floating plants), seaweed form the base of the food chain in the sea. Plants photosynthesise, use the sun's energy to produce carbohydrates from carbon dioxide and water. They absorb the nutrients that they need from the surrounding water.
Three groups of seaweeds are recognized, according to the pigments which absorb light of particular wavelengths and which give them their characteristic colours of green, brown or red. Because they need light to survive, seaweeds are found only in the relatively shallow parts of oceans, which means around the shores.
At present, marine life is being studied more than it ever was in the past and, with our increased understanding of life in the sea, should come a greater appreciation of the importance of seaweeds in nature and to humans.