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Interesting Facts about Algae
The AlgaeBase database suggests the exact number of algal species is over 50,000 and they categorise them into four distinct kingdoms (Plantae, Protozoa, Eubacteria, and Chromista).
This guide explains how and where algae grows, and how a large group of diverse nonflowering, plant-like aquatic eukaryotic organisms has benefits for marine ecosystems.
What are Algae and Where Do They Grow?
Photosynthetic organisms may be some of the simplest forms of life on earth. Yet, they range in size from the tiny microscopic phytoplanktons to large clumps of seaweeds.
Worldwide, the different types of algae grow in various kinds of aquatic environments, including:
- Saltwater (e.g. tidal pools, seas, estuaries, and oceans)
- Freshwater (e.g. lakes, ponds, streams, and rivers)
- Some "slightly moist" surfaces (e.g. rocks, sand, plants, tree trunks)
Algae also grows on some man made structures, such as the inside of water tanks, on boat hulls, glass aquariums, swimming pools, and fountains.
Fun Fact: Even though algae lack a typical root system, stem, and leaves like "true" plantlife, some forms develop symbiotic relationships with other organisms, especially corals, lichens, and sponges (phylum Porifera).
Why is Algae So Important?
Through the process of photosynthesis (converting sunlight into energy), the amount of oxygen produced by algal species is close to 70% of the Earth's oxygen.
Moreover, they create a vital food source that forms the cornerstone of the aquatic food chain in both marine and freshwater ecosystems. In fact, scientists also use the density of their populations as important "environmental indicators".
Interesting Fact: Ongoing research suggests algae may be an efficient source for biofuel production, mainly due to the rapid growth rate and high oil content. The primary benefits of algae biofuels (e.g. biodiesel and bioethanol) over fossil fuels, is the reduced greenhouse gas and carbon emissions.
Different Types of Algae
- Phaeophyta are multicellular "autotrophic" (able to make their own food) brown algae. Some of the biggest and most common strains include seaweeds and kelp.
Chlorophyta are the green coloured algae that grows in freshwater and inside fish tanks (e.g. green hair algae). As most aquarium hobbyists will know, some species are beneficial (e.g. for providing food and oxygen), but many are problematic because excessive algae often leads to oxygen depletion and clogged aquarium filters.- Cyanobacteria are a blue-green variety that falls under a group of autotrophic gram-negative bacteria capable of producing toxins.
- Rhodophyta are red coloured algae found most often in saltwater marine environments (especially deep water).
- Diatoms are microscopic algae that have silica-based cell walls. These are the species that form a major part of planktonic materials.
Sea Lettuce (Ulva lactuca)
Sea lettuces make up several species of the green coloured algae under the Ulva genus. Like many of the funny fish names, they also get the common name from their resemblance to leafy lettuces.
You will find some species of sea lettuce seaweed growing near the coastal regions of marine and brackish environments around the world. The edible green alga tend to be slender and green - some with curved or ruffled edges.
Here's the thing:
In nutrient-rich ecosystems, the rapid growth rate often results in the formation of dense carpet-like mats - known as algae turf. They often attach themselves to rocks and other hard surfaces in shallow waters (e.g. crustacean shells).
Sea lettuce (Ulva lactuca) is the preferred diet for most herbivorous marine species, especially small fishes and sea slugs (nudibranchia).
Using Sea Lettuce in Aquariums
With good lighting and efficient water flow, experienced aquarists use sea lettuce in marine aquariums - or refugiums (often used to promote the growth or reproduction of targeted plants and animals) - as a food source for many of the most popular aquarium fish kept by hobbyists.