Deep Sea Mushroom Expands Tree Of Life

A ‘mushroom’-shaped animal found in a deep sea expedition is forcing scientists to rethink their tree of life. While the deep sea mushroom defies modern classifications, the mushroom-like creature could be related to groups thought extinct for 500 million years.

The discovery was published in PLOSone, an open access journal. The article explains the difficulties of classifying the deep sea mushroom using current taxonomies–at once both animal and mushroom-shaped. Co-author Jorgen Olesen from the University of Copenhagen told BBC News:

Finding something like this is extremely rare, it’s maybe only happened about four times in the last 100 years […] We think it belongs in the animal kingdom somewhere; the question is where.

Nature News, published by the leading journal Nature reports:

The researchers classified the organisms under a new genus, Dendrogramma — a reference to dendrograms, the tree diagrams used in biology to illustrate evolutionary relationships between organisms. The two species names, enigmatica and discoides, allude to their mysterious character and disc shape, respectively.

To classify the deep sea mushroom, scientists created a new species, genus, and family (Dendrogrammatidae).

While the creature is clearly not a ‘mushroom’ or fungus, this article will refer to it as a ‘deep sea mushroom’–mostly out of amusement and of respect for the mushroom’s discoverer, Jean Just, who calls them “little, funny, mushroom-shaped animals.”

National Geographic reports that ‘deep sea mushroom’ isn’t inappropriate:

The tiny animals, less than an inch long (two centimeters) when alive, are translucent and look superficially similar to chanterelle mushrooms…But the relationship ends there. What looks like a mushroom’s stalk on Dendrogramma has a mouth at the base leading to a digestive canal that forks repeatedly once it reaches a disk, which looks like a mushroom cap.

Deep sea mushrooms were a long-time coming. These deep sea mushrooms were dredged up in the Tasman Sea in 1986 at a depth of 400 and 1,000 meters. The mushroom was fixed in preservatives (formaldehyde then alcohol) and brought back to Dr. Just’s laboratory, who is a zoologist at the Natural History Museum of Denmark. Here it remained until Dr. Just discovered the deep sea mushrooms for yet a second time.

Dr. Just’s discovery isn’t just a deepened or mushroomed curiosity. Dr. Moroz, a neurobiologist at the University of Florida, says the deep sea mushrooms could:

[C]ompletely reshape the tree of life, and even our understanding of how animals evolved, how neurosystems evolved, how different tissues evolved […] It can rewrite whole textbooks in zoology.

Such evolutionary talk (even if related to deep sea mushrooms) reminds one of the monkey selfie, which promises to expand evolutionary neuroscience.