What is the Largest Organism?

Naming the world's largest organism is complicated by what you define as an "organism". Certain invertebrates, such as coral and fungus, aggregate into collectives called superorganisms. Hence, the world's largest superorganism, the Great Barrier Reef, sometimes gets the title.

There is also a fungus called Armillaria ostoyae, or the honey mushroom, that forms fungal mats as long as 8.9 km² (2200 square acres or 3.5 square miles), although there is disagreement as to whether the entire mat qualifies as a single organism. The largest example of this fungus can be found in a national forest in Oregon. It is estimated to be 2,400 years old.

If you ask which obviously individual largest organism receives the title, it falls to the Giant Sequoia called General Sherman, which can be found in California. This is generally accepted at the world's largest organism. It has a volume of 1,489 cubic meters, or 52,583 cubic feet. Despite this, pages referencing the Oregonian honey mushroom rank highest for Google searches for "largest organism".

Mushrooms and trees aside, the world's largest animal ever known to have lived is the blue whale, whose heart is the size of a Volkswagen bug. These underwater giants weigh up to 180 tons and can be as long as 30 meters (100 feet). At birth, they are the size of a fully grown hippopotamus. Because so many blue whales were killed in the early 20th century in the Antarctic by sailors unversed in scientific measurement techniques, we are not entirely certain how large blue whales can really grow, but they are definitely massive.

The blue whale is only rivaled in size by Argentinosaurus, the largest and heaviest land animal to ever have lived, with a height of more than 40 meters (125 feet) and a weight around 90 tons. Argentinosaurus was an herbivorous sauropod, the largest of its kind that we know of. We have only found a few bones - a single vertebrate was 1.3 m (4.3 ft) long. While not the world's largest organism in general, its appearance in the flesh could probably impress humans even more than any of the aforementioned organisms. Argentinosaurus lived 112.2 to 93.5 million years ago.

Repeatedly, throughout the summer of 1997, an incredibly loud, low-frequency sound was detected by the Equatorial Pacific Ocean autonomous hydrophone array. The sound is very perplexing because it has the acoustic signature of an immense organism with a gas-filled sac. This has since become known as the Bloop. It has been hypothesized this is a new, larger form of whale, but it would need to surface every once in a while, which would make it visible occasionally. So the Bloop remains a mystery, but it could end up being the call of the world's true largest organism, or at least its largest animal.

One day we may discover an even larger organism. Life on other planets or genetically engineered life probably has a size limit substantially larger than anything we have ever seen or imagined.

The title of the largest organism goes to the Armillaria ostoyae, or honey fungus, in the Blue Mountains of Oregon. This colossal fungus covers approximately 2,385 acres (965 hectares) and is estimated to be thousands of years old, according to extensive scientific research.

Scientists measured the size of the Armillaria ostoyae by analyzing the genetic material of the fungus across the forest floor. They discovered that the vast network of underground mycelial threads, which are part of the fungus, were genetically identical, indicating that they were all part of one single organism.

While the majority of the Armillaria ostoyae is underground and cannot be seen, the organism produces honey-colored mushrooms that are visible above ground. These mushrooms are the reproductive structures of the fungus and can be spotted during certain times of the year.

The discovery of such a massive organism challenges our understanding of biological size limits and ecosystem dynamics. It provides insights into fungal growth patterns, longevity, and their role in forest ecology. Studying this organism helps scientists understand how similar life forms contribute to nutrient cycling and forest health.

Like many organisms, the Armillaria ostoyae faces threats from environmental changes, including forest management practices, climate change, and disease. Its sheer size and resilience make it robust, but it is not immune to the impacts of human activity and natural forest dynamics.

The Armillaria ostoyae reproduces both sexually and asexually. It spreads asexually through its mycelium, which grows underground to colonize new areas. For sexual reproduction, it produces spores through the mushrooms that disperse and can grow into new genetically distinct individuals if conditions are favorable.