In the story I'm writing, Goblins have evolved a symbiotic relationship with a type of algae which grows in their skin. I was wondering - what kinds of biological benefits would a symbiotic relationship with an algae provide to the host?

NOTE: Magic does not exist in my story.

Edit: i guess another thing I'm curious about is whether or not this would affect their migration into Eurasia and other frigid regions?

  • $\begingroup$ What kind of symbiotic relationship, does it grow in their colon, do they farm it what? It is fairly central to making the question answerable. $\endgroup$
    – John
    Commented Feb 7, 2020 at 20:22
  • $\begingroup$ Oophila amblystomatis is a type of algae that has a symbiotic relationship with the eggs of the spotted salamander. $\endgroup$
    – user69935
    Commented Feb 7, 2020 at 20:38
  • 1
    $\begingroup$ Are you sure hard science is the right tag for this? I don't know if you'll find any scientific papers detailing symbiosis between mammals and algae. You will probably get more relevant answers - and more answers in general - without the hard-science tag. $\endgroup$
    – Zxyrra
    Commented Feb 7, 2020 at 20:46
  • $\begingroup$ @Starfish Prime I removed to make way for the symbiosis tag scene it said i could only have five tags $\endgroup$
    – icewar1908
    Commented Feb 7, 2020 at 23:12

2 Answers 2



Your answer already exists on the SLOTH!

Check the lil buddy with his green coat.

"It is a popular assumption that algae in particular form a symbiotic relationship with the sloth, obtaining shelter and a good supply of water as sloth fur absorbs water extremely readily, and providing in return camouflage and extra nutrients via diffusion and absorption through the hair and skin."



If you decide your algae is living on your orcs, you are defining a commensalism, not a symbiotic relationship.

As a human, algae, specifically blue green is toxic to humans. So if this is the algae you are using, your orcs will need a tolerance to the toxins emitted by the algae.

Algae also comes in forms like kelp which can grow to hundreds of feet in length.

Sticking with a symbiotic relationship, your orcs could provide expanded environments for their algae farming enterprises. Having caretakers, the algae could have a variety of forms it takes when grown in particular conditions that produce foods and medicines for your orcs. Consumption or using these as ointments etc, would contribute to the "green" of your orcs.

Maybe one version of algae is brewed into a popular alcoholic drink. Consuming it could cause bioluminescence or phosphorescence. Maybe your orc Mardi gras is a "glowing" spectacle.

Kelp could be a form of clothing or armor that "grows" giving the orcs a special kind of protection and does something in combat that is advantageous to make and wear algae armor.

The more "uses" your orc society makes of the algae grown, harvested, processed into products, the greener they become, the more dependent on the algae activities they would be.

Your orc shaman might smoke certain algae that gives them "visions", or special insights. Dune harvested spice to warp space time. Maybe not quite that level, but it could be useful in your storyline.

Final note: Orcs from Tolkein and other references aren't actually green, they are more grey.


Not the answer you're looking for? Browse other questions tagged .