Algae

Algae are photosynthetic organisms that appear in the How to Train Your Dragon Franchise.

Description
The term "algae" refers to a large group of non-Animal organisms that are able to photosynthesize, but are not as complex as the higher organisms most of us know as Plants. That said, algae contains species from the Plant, Protist, and Bacteria Kingdoms. Classification can even get more complicated than that. Algae can be single-celled organisms or huge complex ones. Algae typically have some sort of photosynthetic process to derive energy (using the sun and producing oxygen as a by-product), but not all species.

Large, multi-cellular algae is generally referred to as Seaweed. Glowing Algae is a construct - based partly in reality - of the Franchise.

Function
Algae are mentioned mostly for educational purposes in the How to Train Your Dragon Franchise. Please see the respective pages for Seaweed and Glowing Algae for other specific uses.

In reality, some species of algae can be directly ingested as food, or made into food products like agar, alginate as a thickener, or carrageenan as a thickener. Algae can be a good fertilizer, an energy source, and even a source of natural dyes. Algae can also be detrimental to the environment, when there is an "algal bloom". This is an event in which algae overgrows and essentially coats the surface of a body of water, potentially choking off oxygen and sunlight to organisms beneath the surface. Some algal bloom species can even produce toxins that sicken humans and cause massive fish deaths.

School of Dragons
In the Quest, "Learn About the Food Chain", Phlegma asks the player to talk to Ruffnut about algae.

"Of course I know about algae! It kind of stinks sometimes, but the mosquitoes love it. Yuck!"

- Ruffnut in School of Dragons

She further elaborates that mosquitoes eat algae; specifically the larval stages of some mosquito species do.

Algae also appears in the Stable Quest "Bloomin' Buffet", in which a player can send their non-active dragons to clean up an algae bloom (of the non-glowing kind). The Flightmare has the largest chance of success. The quest states: "This dragon ... eats more than glowing algae."

"There has been a large algae bloom in the streams, heading towards the ocean. It threatens aquatic and terrestrial wildlife. Can you send a dragon to clean up this algae?"

- School of Dragons