Marine Algae

Marine Biology Unit #2

Unicellular Algae The unicellular algae show plant-like and

animal-like characteristics.

Algae are eukaryotic, photosynthetic organisms.

Unicellular algae are included in the Kingdom Protista.

Unicellular Algae Diatoms:

Diatoms are efficient photosynthetic factories, producing much-needed food, as well as oxygen for other forms of life.

They are very important open water primary producers in temperate and polar regions.

Unicellular Algae Dinoflagellates:

They are more common in the tropics.

Responsible for huge blooms called red tides.

Dinoflagellates are also noted for the production of bioluminescence.

Multicellular Algae Commonly called “Seaweeds.”

More complex than unicellular algae. Being algae, seaweeds lack the true leaves, stems, and roots of the higher plants. Body is a thallus.

Three types of seaweeds are the green, brown, and red algae.

Seaweed Structure The general structure of seaweed is analogous to land

plants, but being algae, seaweed lack the true leaves, stems, and roots.

Blades – huge surface are for photosyntesis

Pneumatocysts – gas-filled bladders for bouyancy

Stipes – growth and flexibility

Holdfast – anchorage to substrate

Seaweed Structure

Division Chlorophyta Green Algae (major oxygen producers) Mostly freshwater and terrestrial Most are unicellular and filamentous Some marine species are multicellular Found in shallows

Division Rhodophyta Red algae. Grow deeper than other algae. There are more species of marine red algae than of green and brown algae combined. Coralline red algae deposit calcium carbonate which helps form and develop coral reefs.

Division Phaeophyta

Brown Algae (commonly called “Kelp”) Almost all marine. Major primary producers on temperate rocky coasts.Macrocystis – “giant kelp” Form kelp forests.

Division Phaeophyta

Kelp Forests

Kelp Forests Enormous primary productivity, analogous to a terrestrial

tropical rain forest in their complexity.

Kelp forests are the basis of recreation and fisheries on North America’s west coast.

In the colder waters of the north and south Atlantic and Pacific Oceans, kelp beds, or forests are formed when many plants, each with many fast-growing and intertwined stripes form dense and very productive regions.

Kelp Forests

Kelp Forests

Uses for Seaweeds Harvested seaweed is used in many ways. The most

obvious is as a food source. The farming, or mariculture, of seaweed is big business in

China, Japan, and Korea. Alginates (from brown algae) Carrageenan (from red algae) These compounds are used as stabilizers and emulsifiers

ice cream, cheese, and topping shampoo, shaving cream and cosmetics plastics and pesticides