Micro & Macro Algae in Seawater

Brown Algae

• There are about 1,500 species of brown algae, also known as the phylum phaeophyta. The macro algae generally grow in the colder ocean regions and in deep water. They are often exposed to great stress from wave action. Brown algae, which includes some of the best-known seaweeds, are known for their large size, including the largest of all algae, Macrocystis pyrifera or brown kelp, which can grow to 50 meters.

Red Algae

• Red algae, or rhodophyta, are photosynthetic organisms that are generally red or purple in color. The phylum possesses 4,000 marine species, with a few freshwater species. They are multicellular organisms that possess macro varieties, and include most of the world's seaweeds. They are most commonly found in tropical and temperate climates, and in these environments can occur at greater depths than other photosynthetic organisms. Many of the coralline algae, which play a major role in the world's barrier reefs, are members of the red algae group.

Dinoflagellates

• Members of the phylum dinoflagella are mostly photosynthetic, although heterotrophic species do exist. The vast majority of the dinoflagellates live in marine habitats and there are more than 2,000 described species. Dinoflagellates are mostly microscopic, unicellular algae, with two flagella to power them through the water. They reproduce asexually and, because they often are important elements in plankton, are a major food source in the warmer regions of the world's oceans.

Diatoms

• Diatoms are microscopic, unicellular algae that are characterized by an often intricately sculpted silica shell. They generally prefer to live singly, rather than in large colonies, and are commonly yellow or brownish in color. Diatoms reproduce asexually by means of cell division. The skeletons of diatoms have deposited most of the world's limestone and a great deal of its petroleum.