Seaweed is a term applied to multicellular, marine algae which are large enough to be seen by the eye unaided. Some can grow to up to 60 metres in length. Seaweeds include members of the red, brown and green algae. They are members of the kingdom Protista meaning they are not Plants. They do not have the vascular system (internal transport system) of plants and do not have roots, stems, leaves and flowers or cones. Like plants they use the pigment chlorophyll for photosynthesis but also contain other pigments which may be coloured red, blue, brown or gold.
Blue-green algae are not marine algae. They are in a group called cyanobacteria and are more closely related to bacteria. Some cyanobacteria form brown, green, red or purple tufts on coral reefs.
To survive seaweeds need salty or brackish water, sunlight and a surface to attach themselves to. Because of these factors they are generally found in the littoral zone (this includes the intertidal zone but generally extends out much further). They are usually found on rocky rather than on sand or shingle shores.
Seaweeds are a food source for marine animals such as sea urchins and fishes, and are the base of some marine food webs. They also provide shelter and a home for numerous fishes, invertebrates, birds and mammals.
The kelps form dense forests which support entire underwater communities providing both food and shelter. Intertidal seaweeds can be exposed to many environmental stresses including drying out when not under water, temperature and salinity changes and wave action.
Kelp (a brown alga) forest
Structure of seaweeds
Thallus: the entire body of a seaweed. Lamina: a flattened structure that is resembles a leaf. Sorus: a cluster of spores spore. Air bladders: a hollow, gas-filled structure organ which helps the seaweed float, found on the blade). Other seaweeds (e.g. kelp) have floats which are located between the lamina and stipe. Stipe: a stem-like structure, not all seaweeds have these. Holdfast: a specialized structure on the base of a seaweed which acts as an “anchor” allowing it to attach to a surface (e.g. a rock). Haptera: finger-like extensions of holdfast anchoring to benthic substrate.
Seaweeds play a very important roles in many marine communities. They are a food source for many marine animals such as sea urchins and fishes, and form the base of some food webs. They also provide shelter and a home for numerous fishes, invertebrates, birds, and mammals.
Structure of marine algae
Seaweed Reproduction
Seaweed life and reproductive cycles can be quite complicated. Some seaweeds are perennial, living for many years, while are annuals. Annual seaweeds generally begin to grow in the spring, and continue throughout the summer. Some red seaweeds have a life span of 6 to 10 years.
Seaweeds can reproduce sexually, by the joining of specialized male and female reproductive cells, called gametes. After they are released from the sporophyte, the spores settle and grow into male and female plants called gametophytes. The gametophytes produce gametes (sperm or eggs). The sperm and eggs are either retained within the gametophyte plant body, or released into the water. Eggs are fertilized when the sperm and egg fuse together, and a zygote is formed. Zygotes develop and grow into sporophytes, and the life cycle continues.
Seaweeds display a variety of different reproductive and life cycles and the description above is only a general example of one type, called alternation of generations. In a few species there is an alternating sexual and asexual reproductive process with every generation.
Seaweeds can also reproduce asexually through fragmentation or division. This occurs when parts of a plant break off and develop directly into new individuals. All offspring resulting from asexual reproduction are clones; they are genetically identical to each other and the parent seaweed.
Reproduction of algae
Carrageean products
Agar plates
Uses of Seaweed
Seaweeds area food source for humans especially in East Asia, it is most commonly associated with Japanese food. Seaweeds also are used to make a number of food additives such as alginates and carrageenan which is used in cooking and baking as a vegetarian alternative to gelatine.
Many seaweeds are used as medicine. Alginates are used in wound dressings and in the production of dental moulds and agar is used very widely in Microbiology to help grow bacterial cultures.
Seaweeds are ingredients in toothpaste, cosmetics and paints and are used in industrial products such as paper coatings, adhesives, dyes, gels, explosives and many more.
Much of the oil and natural gas we use today formed from seaweeds which partially decomposed on the sea floor many millions of years ago.
Japanese food uses seaweeds extensively - Kombu a brown alga and Kim nori a red alga
Algae: The World's Most Important Plants Believe it or not, your life depends on algae! Join Scripps' Institution's Russell Chapman as he discusses the important roles algae have played in the development of life as we know it. Series: "Perspectives on Ocean Science" [12/2006] [Science] [Show ID: 11931]
Thanks to I would sincerely like to thank the many members of the Flickr community who have given me permission to use their wonderful images for this unit. Their contributions really make this unit come alive!
As autotrophic organisms, algae convert water and carbon dioxide to sugar through the process of photosynthesis. Photosynthesis also generates oxygen as a byproduct, contributing to the survival of fish and other aquatic organisms.
All algae, including Pacific Ocean algae, have chlorophyll; however, most lack stems, vascular tissue, roots, and leaves. They play an important role in today's aquatic ecosystems by forming the energy base of the food chain for all marine life and organisms.
Marine algae and their derivatives like Irish Moss and Astaxanthin are considered to be very nutrient-rich and are high in minerals as well as vitamins. They also are super anti-inflammatory, making them a great ingredient to include in products geared towards sensitive and acne-prone skin.
Seaweeds are now used in several industrial products as raw materials such as agar, algin, and carrageenan, but they are still widely consumed as food in several nations [5].
Even if algal blooms are not toxic, they can hurt aquatic life by blocking out sunlight and clogging fish gills. Harmful algal blooms can also create “dead zones,” areas in water with little or no oxygen where aquatic life cannot survive.
Algae provide much of Earth's oxygen, serve as the food base for almost all aquatic life, and provide foods and industrial products, including petroleum products. Their photosynthetic pigments are more varied than those of plants, and their cells have features not found among plants and animals.
On their own, algae and cyanobacteria are not good or bad. They are organisms that are important to the earth because they produce the oxygen needed to sustain life. However, if too much algae or cyanobacteria grow at once or if they make toxins, they can harm people, animals, and the environment.
Marine algae supply much of the world's oxygen supply and take in a huge amount of atmospheric carbon dioxide. The evaporation of the seawater provides rainwater for the land.
Large-scale industrial cultivation of marine microalgae has been shown to be a promising, environmentally-favorable approach for society to meet its climate goals by sustainably coproducing liquid hydrocarbon fuels and protein.
In addition to making organic molecules, algae produce oxygen as a by-product of photosynthesis. Algae produce an estimated 30 to 50 percent of the net global oxygen available to humans and other terrestrial animals for respiration.
Algae are considered to be the most efficient biological system for harvesting solar energy and for the production of organic compounds via the photosynthetic process.
"Seaweed" is the common name for countless species of marine plants and algae that grow in the ocean as well as in rivers, lakes, and other water bodies.
Macroalgae are classified into three major groups: brown algae (Phaeophyceae), green algae (Chlorophyta), and red algae (Rhodophyta). As all of the groups contain chlorophyll granules, their characteristic colors are derived from other pigments.
The role of algae in the ecosystem is essential that includes: Algae are responsible for fixing 60 percent of carbon dioxide.Algae are used for biomass creation.Algae are used in biofuel production.
Algae are the most important photosynthesizing organisms on Earth. They capture more of the sun's energy and produce more oxygen than all plants combined. They form the foundation of most aquatic food webs, which support an abundance of animals.
Simply put, algae are an essential part of a healthy marine ecosystem because they capture and use energy from sunlight, carbon dioxide, and water to produce organic compounds. This cycle helps maintain the balance of life in the ocean.
The most important marine ecosystems for marine life are estuaries and coral reefs. These two marine ecosystems are important because the estuaries are breeding territories for many marine animals, because it is easy for young-lings to survive there, since there are no known predators that live in that region.
Introduction: My name is Aracelis Kilback, I am a nice, gentle, agreeable, joyous, attractive, combative, gifted person who loves writing and wants to share my knowledge and understanding with you.
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