Kelp vs. Alga — What's the Difference?
By Urooj Arif & Maham Liaqat — Updated on March 30, 2024
Kelp refers to large brown seaweeds of the order Laminariales, while alga encompasses a broad range of photosynthetic, aquatic organisms.
Difference Between Kelp and Alga
Table of Contents
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Key Differences
Kelp is a specific type of marine alga, characterized by its large, complex structure and ability to form underwater forests in cold, nutrient-rich waters. In contrast, alga includes a diverse array of photosynthetic organisms, ranging from microscopic phytoplankton to the large seaweeds, including kelp.
While kelp thrives in cold, shallow seas and forms dense aggregations known as kelp forests, offering habitat and food for marine life, algae can be found in various environments, including freshwater lakes, rivers, and damp terrestrial habitats, as well as in the ocean.
The term "alga" covers both single-celled organisms like diatoms and multicellular forms such as seaweeds and kelp, indicating a vast diversity in size, form, and ecological roles. Kelp, however, specifically refers to the larger, multicellular seaweeds in the order Laminariales, known for their fast growth and extensive canopy-forming capabilities.
Algae play a crucial role in aquatic ecosystems, contributing significantly to oxygen production and forming the base of the food web. Kelp forests, a subgroup of algae, are especially important for biodiversity, providing shelter and nutrients to a wide range of marine species.
Kelp is harvested for its alginate, a valuable thickening agent used in food and products, highlighting its economic importance. While algae, in general, are utilized in a variety of ways, including as biofuels, nutritional supplements, and in wastewater treatment.
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Comparison Chart
Definition
Large brown seaweeds of the order Laminariales.
A broad category of photosynthetic, aquatic organisms.
Environment
Cold, nutrient-rich shallow seas.
Diverse, including freshwater and marine environments.
Size and Form
Large, multicellular, and complex structures.
Ranges from microscopic to large seaweeds.
Ecological Role
Forms kelp forests, providing habitat and food for marine life.
Plays a key role in oxygen production and the aquatic food web.
Diversity
A specific subgroup within the broader category of seaweeds.
Includes a vast array of species, from single-celled to multicellular.
Economic Use
Harvested for alginate, used in food and various products.
Used in biofuels, nutritional supplements, and wastewater treatment.
Compare with Definitions
Kelp
A type of large brown seaweed belonging to the order Laminariales.
Kelp forests are vital ecosystems off the coast of California.
Alga
Photosynthetic organisms found in aquatic environments.
Algae blooms can dramatically affect water quality and marine life.
Kelp
Thrives in cold, nutrient-rich waters.
The nutrient upwelling in the Pacific provides an ideal environment for kelp.
Alga
Fundamental to oxygen production and the food web.
Algae are a primary food source for many marine organisms.
Kelp
Characterized by its large size and complex structure.
Kelp can grow up to 18 inches a day under optimal conditions.
Alga
Can inhabit a wide range of environments, including freshwater.
Green algae are common in freshwater ponds and lakes.
Kelp
Creates underwater forests that support diverse marine life.
Kelp forests shelter fish, invertebrates, and marine mammals.
Alga
Used in biofuels, food supplements, and environmental management.
Spirulina, a type of algae, is harvested for its nutritional value.
Kelp
A source of alginate, a substance used in food and products.
Alginate from kelp is used in ice cream as a thickening agent.
Alga
Includes both single-celled and multicellular species.
Diatoms are a type of single-celled alga that contribute to oceanic phytoplankton.
Kelp
Kelps are large brown algae seaweeds that make up the order Laminariales. There are about 30 different genera.
Alga
Any of numerous photosynthetic organisms of aquatic or moist habitats, ranging in size from single-celled diatoms to large seaweeds such as kelp, and characterized by a lack of complex organs and tissues. Once classified within the plant kingdom, the algae are now considered to include several unrelated groups belonging to different kingdoms.
Kelp
Any of various brown seaweeds of the order Laminariales, often growing very large and forming dense beds.
Alga
(biology) Any of many aquatic photosynthetic organisms, including the seaweeds, whose size ranges from a single cell to giant kelps and whose biochemistry and forms are very diverse, some being eukaryotic.
Kelp
The ashes of seaweed, formerly used as a source of potash and iodine.
Alga
A kind of seaweed; pl. the class of cellular cryptogamic plants which includes the black, red, and green seaweeds, as kelp, dulse, sea lettuce, also marine and fresh water confervæ, etc. The algae are primitive chlorophyll-containing mainly aquatic eukaryotic organisms lacking true stems and roots and leaves.
Kelp
Any of several large brown algae seaweeds (order Laminariales).
Alga
Primitive chlorophyll-containing mainly aquatic eukaryotic organisms lacking true stems and roots and leaves
Kelp
The calcined ashes of seaweed, formerly used in glass and iodine manufacture.
Kelp
(intransitive) To gather kelp.
Kelp
The calcined ashes of seaweed, - formerly much used in the manufacture of glass, now used in the manufacture of iodine.
Kelp
Any large blackish seaweed.
Kelp
Large brown seaweeds having fluted leathery fronds
Common Curiosities
What are some common uses of algae in human industries?
Algae are used in various industries for biofuel production, as nutritional supplements (e.g., Spirulina), in wastewater treatment, and as thickening agents in foods and cosmetics.
What makes kelp different from other algae?
Kelp is a large, multicellular seaweed known for forming underwater forests, distinct from other algae by its size, complexity, and habitat.
Are kelp forests found in freshwater?
No, kelp forests are exclusive to marine environments, particularly in cold, nutrient-rich waters.
Can algae grow in polluted waters?
Some algae can thrive in polluted waters and can indicate the health of an aquatic ecosystem, although excessive growth, or blooms, can be detrimental.
Why are kelp forests important to marine biodiversity?
Kelp forests provide habitat, shelter, and food for diverse marine species, contributing significantly to the biodiversity and productivity of marine ecosystems.
How do algae support aquatic food webs?
Algae serve as a primary food source for a wide range of aquatic organisms, from small invertebrates to large marine animals.
Is kelp edible?
Yes, kelp is edible and is used in various cuisines, particularly in Asian dishes, for its nutritional value and flavor.
How do humans benefit from algae?
Humans benefit from algae through their use in foods, health supplements, environmental applications, and as a potential renewable energy source.
Can all algae produce oxygen?
Yes, all algae, through photosynthesis, contribute to oxygen production in their respective aquatic environments.
What challenges do kelp forests face?
Kelp forests are threatened by climate change, pollution, overfishing, and changes in sea temperatures, which can reduce their extent and health.
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Written by
Urooj ArifUrooj is a skilled content writer at Ask Difference, known for her exceptional ability to simplify complex topics into engaging and informative content. With a passion for research and a flair for clear, concise writing, she consistently delivers articles that resonate with our diverse audience.
Co-written by
Maham Liaqat
