Mermaid’s Fan Algae (Udotea flabellum) – Fascinating Facts

Mermaid's Fan Algae Featured Image

Mermaid’s Fan Algae, or Udotea flabellum, is a type of green macroalgae that uses sunlight to make food.

It’s commonly found in shallow waters around places like Florida and Belize. This algae grows in sandy areas, seagrass beds, and coral reefs.

It’s known for its ability to fight germs and is even being studied for use in cancer treatments.

What Does Mermaid’s Fan Algae Look Like?

Udotea flabellum gets its nickname, Mermaid’s Fan Algae, from its fan-shaped growth.

This algae attaches itself to the ground using a system of root-like structures called rhizoids.

It doesn’t have a stem, leaves, roots, or a system for moving water and nutrients as some plants do. Instead, it has a stem-like feature called a stipe.

The fan-shaped part of the algae called the thallus, is often divided into sections called lobes.

These lobes are thick, leathery, and have a moderate amount of calcium in them. The stipe is also often calcified, which means it has calcium in it too.

Where Can You Find Mermaid’s Fan Algae?


Species of the Udotea genus, like Mermaid’s Fan Algae, are found in warm tropical and subtropical locations.

Mermaid’s Fan Algae is found in many places around the world, such as North America, the Atlantic islands, Mexico, the Caribbean, South America, the Indian Ocean, Africa, Australia, New Zealand, and Asia. These algae are often found in coral reefs.


Mermaid’s Fan Algae can also grow on sandy coastlines and in seagrass beds. It’s found at depths of up to 23 meters.

When Mermaid’s Fan Algae dies, its calcified thallus and stipe improve the nutrients in the sediment and contribute to sediment production.

This can help the coral reefs in the area to continue growing. Algae like Mermaid’s Fan Algae are also important for the food webs in reefs.

As photosynthetic plants, they contribute to primary production, which is the synthesis of organic compounds from carbon dioxide. This algae provides a food source for marine herbivores.

What Research Has Been Done on Mermaid’s Fan Algae?

Increasing Plasma Coagulation Time

In one study, an extract of Mermaid’s Fan Algae was found to be the most effective out of several tropical green seaweeds tested.

It increased plasma coagulation time, which is the time it takes for blood to clot. This is important in helping to prevent excessive bleeding.

Antimicrobial Activity

An extract of Mermaid’s Fan Algae in ethanol showed modest activity against harmful microbes.

In one experiment, it was found to fight against Staphylococcus aureus, a type of bacteria, and Candida albicans, a type of fungus.

Researchers isolated a new compound from the algae extract called udoteatrial, which they believed to be responsible for the antimicrobial activity.

How Can Mermaid’s Fan Algae Be Used?

Antimicrobial Properties

Because of its ability to fight germs, Mermaid’s Fan Algae is used for its antimicrobial properties.

This could potentially be used in the development of new medicines or treatments for infections caused by bacteria and fungi.

Cancer Treatment Studies

Mermaid’s Fan Algae is also being studied for use in cancer treatments.

While more research is needed, the algae’s potential in this area could lead to new therapies and treatments for cancer patients in the future.

You can check out what this plant looks like over here.

Udotea flabellum Characteristics

Care Level:Easy
Growth Rate:Moderate
Nutrient Uptake:Fair
Required Lighting:Moderate High
Required Water Flow:Moderate
Is Palatable?No
Maximum Size:12 in (30.5 cm)

Scientific Classification

Scientific Name:Udotea flabellum
Also Known As:Mermaid’s Fan Algae
Conservation Status:Unknown

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