Largest Living Organism is Not the Blue Whale

The largest living organism, once considered to be the blue whale, might not be what you expect. The discovery of a giant fungus in Oregon has claimed the prize.

W.J.Pilsak (Walter J. Pilsak, Waldsassen)

W.J.Pilsak (Walter J. Pilsak, Waldsassen)

via Scientific American:

The discovery of this giant Armillaria ostoyae in 1998 heralded a new record holder for the title of the world’s largest known organism, believed by most to be the 110-foot- (33.5-meter-) long, 200-ton blue whale. Based on its current growth rate, the fungus is estimated to be 2,400 years old but could be as ancient as 8,650 years, which would earn it a place among the oldest living organisms as well.

A team of forestry scientists discovered the giant after setting out to map the population of this pathogenic fungus in eastern Oregon. The team paired fungal samples in petri dishes to see if they fused (see photo below), a sign that they were from the same genetic individual, and used DNA fingerprinting to determine where one individual fungus ended.

This one, A. ostoyae, causes Armillaria root disease, which kills swaths of conifers in many parts of the U.S. and Canada. The fungus primarily grows along tree roots via hyphae, fine filaments that mat together and excrete digestive enzymes. But Armillaria has the unique ability to extend rhizomorphs, flat shoestring like structures, that bridge gaps between food sources and expand the fungus’s sweeping perimeter ever more.

A combination of good genes and a stable environment has allowed this particularly ginormous fungus to continue its creeping existence over the past millennia. “These are very strange organisms to our anthropocentric way of thinking,” says biochemist Myron Smith of Carleton University in Ottawa, Ontario. An Armillaria individual consists of a network of hyphae, he explains. “Collectively, this network is called the mycelium and is of an indefinite shape and size.”

All fungi in the Armillaria genus are known as honey mushrooms, for the yellow-capped and sweet fruiting bodies they produce. Some varieties share this penchant for monstrosity but are more benign in nature. In fact the very first massive fungus discovered in 1992—a 37-acre (15-hectare) Armillaria bulbosa, which was later renamed Armillaria gallica—is annually celebrated at a “fungus fest” in the nearby town of Crystal Falls, Mich.

Myron Smith was a PhD candidate in botany at the University of Toronto when he and colleagues discovered this exclusive fungus in the hardwood forests near Crystal Falls. “This was kind of a side project,” Smith recalls. “We were looking at the boundaries of [fungal] individuals using genetic tests and the first year we didn’t find the edge.”

Continue reading.

NOTE: According to Wikipedia, Armillaria ostoyae is now known as Armillaria solidipes (the quoted article is from 2007).

11 Comments on "Largest Living Organism is Not the Blue Whale"

  1. Anarchy Pony | Aug 1, 2014 at 2:37 pm |

    But when does it start causing the zombie/fungi(zongi? Fumbie?) apocalypse?

  2. Ashley Johnson | Aug 1, 2014 at 2:40 pm |

    This is so cool.

  3. Number1Framer | Aug 1, 2014 at 7:38 pm |

    I’ve heard this is a bit of a contested issue and depends on the definition of “largest” being used. Another one I’ve heard of is a massive stand of aspens in Colorado that are all genetic clones growing from one root structure. I picture scientists throwing pies in each other’s faces a la The Far Side while debating this.

  4. Rhoid Rager | Aug 1, 2014 at 9:54 pm |

    If I was an alien, this is how I would colonize a planet–subtly, slowly, and deeply. I would even manufacture some drones to convince the megafauna of my importance.

    • Echar Lailoken | Aug 1, 2014 at 10:27 pm |

      Alien Encounters S02 E01 Invasion covers this with a hypothetical scenario. Large pods that drop all over the world that sit for awhile until they start to divide, and eventually stick to anything and anyone that touch them. Until one day they fall off. I tried to get the video, but no dice. It’s an excellent series.

      • Rhoid Rager | Aug 1, 2014 at 10:37 pm |

        Sounds interesting, but I’m talking colonization over thousands of years, maybe millions. A process so slow that it actually uses genetic evolution as its process of unfolding.

  5. It’s not a “fungus fest”! It’s “The Humongous Fungus Festival.”
    Jeez . . .get the alliteration, eh?

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