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SAR Supergroup
SAR Supergroup
The term protist is an old "catch-all" term for algal-like or fungal-like organisms that didn't seem to fit into other kingdoms. With better technology, the evolutionary relationships of these organisms are being refined. The "protists" that are presented all exist in the SAR supergroup, which is an acronym for the Stramenopiles, the Alveolates, and Rhizaria. They descended from an endosymbiotic event between a bikont (organism with 2 flagella) and a red alga, which became the ancestor of chloroplastid with chlorophyll c. Thus, the photosynthetic members of this group possess both chlorophyll a and c
Classification
Classification
SAR Supergroup (Stramenopiles, Alveolata, Rhizaria)
Infrakingdom Heterokontophyta (or also called Stramenopiles)
Water molds (Oomycota)
Diatoms (Bacillariophyceae)
Brown algae (Phaeophyceae)
Infrakingdom Alveolata
Dinoflagellates (Dinoflagellata)
Infrakingdom Rhizaria (not covered in this website)
Algae
Algae
Algae refer to aquatic, usually photosynthetic organisms; sometimes, they are larger but frequently microscopic.
Seaweed is a term for algae that are usually plant-like and macroscopic in form
Kelp is a specific group of seaweeds that are from the brown algae group
The term "algae" does not refer to any particular taxonomic group; it is a polyphyletic term
There are many unrelated groups referred to as algae, such as blue-green algae (cyanobacteria), red algae (rhodophytes), green algae (chlorophytes), brown algae (phaeophytes), dinoflagellates, and diatoms.
Questions for Thought
Questions for Thought
Why is the term "protist" not very useful for evolutionary studies?
What is the synapomorphy of the Chromalveolates? ... of the Heterokonts? ...of the Alveolates?
What life cycle (i.e., haplontic, diplontic, diplo-haplontic) does each group exhibit?
The brown algae are not closely related to land plants, but what aspect of their life cycle made past researchers assume an ancestor-descendant relationship?
How have the water molds impacted plants and human history?
Why are the diatoms so ecologically significant?
Why are dinoflagellates so ecologically significant?
What ecological niche(s) do the brown algae occupy?
Additional Resources
Additional Resources
Vital seaweed habitats aren't being protected by ocean reserves (Phys.org 4Dec2025)
└Global seaweed stock and Marine Protected Area assessments provide potential opportunities to protect wild seaweeds (Brodie et al, 2025)
A taste of the sea: Comparing five edible seaweeds (Phys.org 28Nov2025)
└Comparative analysis of the nutritional profiles of five edible macroalgae as sustainable food sources (Costa et al., 2025)
New tech to combat toxic algal blooms and fish death events (Phys.org 8Sep2025)
Snow algae accelerate Antarctic ice shelf melting (Phys.org 27Aug2025)
└Liang et al. (2025) Seasonal cycles of snow algal blooms intensify surface melting on Antarctic ice shelves
It isn't all bloom and doom: Why algal blooms are becoming more prevalent (Particle 7Jul2025)
Green algae-based systems improve wastewater recycling for rural and regional communities (Phys.org 4Jul2025)
└Sabatte et al. (2025) High-rate algal ponds operated as sequencing batch reactors: Towards wastewater treatment with filamentous algae
Some sea slugs consume algae, incorporate photosynthetic parts into their own bodies to keep producing nutrients (Phys.org 26Jun2025)
└Allard et al. (2025) A host organelle integrates stolen chloroplasts for animal photosynthesis
How marine microalgae cause buoyant microplastics to sink (Phys.org 23Jun2025)
└Lim et al. (2025) Impact of Heterosigma akashiwo on the environmental behavior of microplastics: Aggregation, sinking, and resuspension dynamics
Stocking up on snacks: How phytoplankton prepare for the future (Phys.org 16Jun2025)
└Anderson et al. (2025) Nutrient storage links past thermal exposure to current performance in phytoplankton
Algae can clean sewage without electricity or chemicals; we put it to the test in South Africa (Phys.org 2Jun2025)
How competition between algae is transforming the gulf of Maine (Phys.org 22May2025)
└Farrell et al. (2025) Turf algae redefine the chemical landscape of temperate reefs, limiting kelp forest recovery
Seaweed surges may alter Arctic fjord carbon dynamics (Phys.org 19May2025)
└Roy et al. (2025) Tracing Macroalgal-Induced Changes in Carbon Dynamics of High-Arctic Fjords Using Biomarker Fingerprinting
Marine Algae Gene Unlocks Potential For Super Crops (Science Blog 6Mar2024)
Climate change clues from tiny marine algae - ancient and modern
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