Smallest Brown Algae

• The other types of algae, green and red, exist in their smallest forms as single-celled organisms that contain all the information and structures needed to thrive. There are no known species of brown algae that are this small; the smallest members of the brown algae family grow in a series of thin strands that cannot be seen by the human eye, but are still much, much larger than their single-celled cousins. These smallest members are still constructed of many cells, and have many individual strands that allow the algae to efficiently absorb the nutrients it needs from the water. Brown algae has no roots, but even these small, microscopic forms of algae will attach themselves to plants and rocks beneath the water.
  
  

Largest Brown Algae

• Sea otters spend most of their lives in the kelp forests.Jupiterimages/Photos.com/Getty Images
  
  The largest forms of brown algae make up the kelp forests, and individual strands can grow up to 200 feet in length. On each of these strands are sophisticated structures known as thallus; these branches and leaf-like structures allow for the sunlight and nutrient absorption that allows the plants to grow so large. They also give the brown algae its forest-like appearance. The giant kelp found in the underwater forests off the coast of California are among the most widespread of the kelp forests, and provide a home for species such as the sea otter. There are also large forests of yellowish brown algae off the coast of Ireland, and tons of this algae are harvested and exported every year.
  
  

Complexity

• There are more than 1,800 different species of brown algae, and many share more features in common with plants. The difference between plants and algae is the complexity of their internal structures, but brown algae has some things in common with the plants that are generally considered to be a higher life form. Other types of algae only have one kind of internal tissue, but because of the complexity of brown algae there is room for differentiation within the algal structure. Different cells do different things, which is only allowed in organisms that contain more than one cell. Because of the size of brown algae, it developed structures for moving nutrients and substances throughout the algae, although it has not evolved to the point of having xylem and phloem like plants.
  
  

Adaptations of Large Algae

• The cooler the water, the larger the brown algae will grow.Jupiterimages/Photos.com/Getty Images
  
  Brown algae, also unlike other types, is generally not found free-floating in the water. Commonly found in reef and coastal environments, brown algae, from the smallest to the largest, has developed structures called holdfasts. These holdfasts attach one end of the algae to a rock, the ocean floor or even to a plant in the case of some of the smaller types of brown algae. These anchor points secure the algae, which has also developed air bladders. These bladders keep the algae floating upright; for large algae like the giant kelp, this means they provide the groundwork for a variety of plants and animals. Mussels and sponges can be found living among the holdfasts where they are protected from predators, while fish take shelter in the leaf-like fronds suspended in the water. Other animals, like otters, live in the canopy.