Welcome to Urban Observation of the Week: Halloween Edition 2019!
This year, we’re celebrating Halloween by featuring an oft-forgotten taxon in the world of urban evolution: fungi. This kingdom is remarkably prepared for a holiday dedicated to all things creepy. Below are some examples of fungi that could go trick-or-treating any day of the year and which have been found living in cities… maybe even your own! Then, keep reading for an in-depth exploration of two fungal species known to induce zombie-like behaviors in their prey.
The spectacular Clathrus archeri, also known as Devil’s Fingers, has been sighted in Christchurch, New Zealand and all over UC Santa Cruz on iNaturalist.
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The shaggy ink cap (Coprinus comatus) is commonly sighted in cities (including throughout New York), as its preferred habitat includes lawns and roadsides (1). When the mushroom is ready to spread its spores, it begins a type of auto-digestion- autodeliquescence- that results in an inky substance that was once used for writing (2).
The “brain mushroom” (Gyromitra esculenta) is a false morel that’s been sighted several times in urban areas such as Portland, Oregon and Ottawa, Ontario.
The aptly-named Jack O’Lantern Mushroom (Omphalotus illudens) has been sighted throughout the greater Washington DC area. It’s prized for its brilliant orange color as well as its bioluminescence. (Photos below by iNaturalist user radmo).
If you’re ready to dive into the world of a couple of fungi specializing in converting insects into zombies, keep reading for descriptions of two truly grisly fungal species known to inhabit cities.
Let’s start with Entomophthora muscae, or Fly Death Fungus.
Entomophthora means “insect destroyer” + Muscae means “of the fly” in Greek, so the entire translation works out as, “insect destroyer of the fly”.
This amazing iNaturalist sighting (right) was reported on the University of Chicago campus (by a human genetics professor, no less!). This pathogenic fungus has also been sighted a couple times in Washington, DC.
About 5 to 7 days prior to this fly’s untimely death, the fly most likely intercepted a spore that had flown off a previous zombie fly. Upon arrival, the spore germinates, penetrates the fly’s exoskeleton, and heads straight for the fly’s brain “in order to control its activities” (3). Once the fungus infiltrates the part of the fly’s brain that handles crawling, it compels the fly to find a landing area and crawl as high as possible. Next, the fungus digests the fly’s guts and kills it before extruding its sporangia (spore-forming structures) through cracks in the fly’s body. Finally, the fungus waits on its elevated host for a breeze that will hopefully carry a spore onto another unassuming fly (3).
Many species of pathogenic fungi strive for widespread spore transmission by positioning their spores as high as possible. Some accomplish this by employing a zombie-like method, like Entomophthora muscae and Entomophthora grylli (a species that targets grasshoppers), while others produce fruiting bodies (3). For example, let’s examine Ophiocordyceps unilateralis.
Ophiocordyceps unilateralis belongs to a genus of fungi known for growing on insects.
This iNaturalist sighting (left) was logged in the city of Manaus, Brasilia, Brazil. Other urban sightings on the citizen science platform are rare, but a zombified ant has also been seen in Lafayette, Louisiana, USA.
The life cycle of O. unilateralis is similar to that of E. muscae in the way that the fungus finds a host (an ant belonging to the Camponotini tribe) and forces it to travel upwards to where the air currents are strongest (4). However, once the hijacked ant reaches its apex, it bites down on the underside of the leaf and waits for death. The fungus spreads throughout the ant’s body until it is mature enough to produce fruiting bodies, which grow from the ant’s head outwards as spindly stalks (5). These fruiting bodies will generate spores which, upon catching the wind, will continue the gruesome cycle.
For more information on fungi in urban environments, check out “Fungi and the urban environment: A review” by Newbound et al. (2010) and this grisly National Geographic vignette showing an ant’s demise after infection by Ophiocordyceps unilateralis.
References:
- Falandysz, Jerzy. “Mercury bio-extraction by fungus Coprinus comatus: a possible bioindicator and mycoremediator of polluted soils?.” Environmental science and pollution research international vol. 23, 8 (2016): 7444-51. doi:10.1007/s11356-015-5971-8
- “Coprinus comatus, the shaggy mane”. Tom Volk’s fungus of the month. May 2004.
- “Entomophthora muscae, a fungus that infects houseflies”. Tom Volk’s fungus of the month. March 2000.
- Lu, Jennifer. “How a Parasitic Fungus Turns Ants into ‘Zombies’.” National Geographic, National Geographic Partners, 18 Apr. 2019, www.nationalgeographic.com/animals/2019/04/cordyceps-zombie-fungus-takes-over-ants/#close.
- Hughes, D., Wappler, T., and Labandeira, C. C. 2011. “Ancient death-grip leaf scars reveal ant-fungal parasitism.” Biology Letters. 7 (1):67–70. https://doi.org/10.1098/rsbl.2010.0521
Featured image: “Ant killed by Ophiocordyceps fungus” by treegrow is licensed under CC BY 2.0.
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- Urban Observation of the Week: Zombies! Brains! Fungi! - October 30, 2019
- What is the “Indoor Biome”? - September 3, 2019
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