These are a few of my favorite species: Desmarestia

This is acid.

Sulfuric Acid

This is your seaweed on acid.

des ligulata

Sulphuric acid to be exact.

A highly corrosive substance, also known as oil of vitriol, H2SO4 is one of those ‘strong acids’ essentially meaning that yes, I actually wear gloves/goggles/lab coat/body armor (if available) when I am using it for legitimate fear of it getting on me and my skin melting off.

While I personally shy away from things that can cause me such bodily harm, certain species of leafy denizens in the genus Demarestia embrace it by actually concocting and harboring Sulphuric acid in their vacuoles. Desmarestia is a hardcore seaweed like that.

Rightly named “Acid Weed,” the internal pH of Desmarestia has been estimated as low as 0.6 pH. For reference, the pH of gastric acid (the stuff in your stomach that liquefies food) sits at roughly 1.5 to 3.5.

des. herbaceaThese caustic brown seaweeds are found primarily in cold-water habitats and compose the dominant aquatic flora in the Antarctic. Though the primary function of Sulphuric acid in Desmarestia tissues is largely unknown, studies have shown that it works rather effectively as a predator deterrent. Go figure.

In my experience, handling Desmarestia with bare hands will not bring harm to the unsuspecting (though I have held other seaweeds that gave me the finger tingles…pretty impressive for a plant). However, when exposed to physical damage or high temperatures, Sulphuric acid released from broken vacuoles will destroy algal tissues. Similarly, if placed in a bucket of water with other live critters, a bucket of un-live critters will result.


Photos: 1. Shutterstock 2. MBARI 3. An Ocean Garden

Eppley RW, Bovell CR. 1958. Sulfuric acid in Desmarestia. Biol Bull Mar Biol Lab: 115:101–106

Pelletreau, KN; Muller-Parker, G. 2002. Sulfuric acid in the phaeophyte alga Desmarestia munda deters feeding by the sea urchin Strongylocentrotus droebachiensis MARINE BIOLOGY : 141 (1): 1-9

Alex Warneke (111 Posts)

Alex currently resides as a Science Communicator for the National Park Service, where she inspires thousands a year to love the watery world. Alex earned her Masters degree in chemical ecology from San Diego State University investigating the effects of heavy metal pollutants on the chemical communication between organisms. In her “free time,” Alex enjoys convincing the public that Ecology is indeed sexy. With that goal, she is a strong proponent of unconventional science communication and extending the broader impacts of science to the general public using the outlets of film and social media. When she is not busy busting a move or filming her next rap video, she can normally be found frolicking through the California kelp forest.

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