Starfish Fungus

Overview

The Starfish Fungus (Aseroe rubra), commonly known as the sea anemone fungus or anemone stinkhorn, is a visually startling gasteroid fungus belonging to the stinkhorn family Phallaceae. Indigenous to the damp eucalyptus forests, temperate rainforests, and coastal scrub of Australia and New Zealand—and famously introduced to garden mulch beds across North America and Europe—this bizarre organism looks like a vivid scarlet sea star or tropical sea anemone that has mysteriously washed ashore in the middle of a forest.

Operating as a vital saprotrophic decomposer within forest floor and suburban landscape soils, Aseroe rubra rapidly breaks down decaying woody debris and damp mulch into rich organic soil nutrients. Famous across chemical ecology for its gruesome reproductive strategy, the center of the red starfish receptacle is coated in a dark, slimy, olive-brown spore mass (gleba) that emits an unbearable stench of rotting meat and sewage, luring blowflies and carrion beetles from miles around to consume the slime and disperse its spores. Flourishing across native forests and urban garden beds globally, it is evaluated as Least Concern.

Biology and Physical Characteristics

The physical and developmental engineering of Aseroe rubra represents an extraordinary mechanical triumph of hydraulic cell expansion: the mushroom begins life subterranean as an unassuming, whitish-tan, gelatinous ‘egg’ measuring two to three centimeters across, anchored to the soil by thick white mycelial strands (rhizomorphs). Inside this egg, the entire red starfish structure is tightly compressed and folded within a gelatinous, water-rich mucilage layer. When moisture and temperature conditions align after soaking rains, the egg ruptures with sudden hydrostatic force, pushing up a hollow, cylindrical, spongy white-to-pinkish stem. At the summit of this stem, the mushroom unfurls a flat, disc-shaped horizontal receptacle that splits into six to ten pairs of radiating, pointed, brilliant scarlet-red arms that curl gracefully at their tips like tentacles. The center of the disc is coated in a thick, sticky layer of olivaceous gleba containing billions of microscopic, smooth, cylindrical basidiospores. Its unbearable stench is generated by a complex chemical mixture of dimethyl trisulfide, putrescine, and cadaverine that mimics decaying vertebrate carrion.

Behavior and Ecology

Starfish fungi fruit primarily during late summer and autumn following warm soaking rains, frequently emerging in small clusters among garden mulch, shaded botanical conservatories, and damp native woodlands. The entire post-emergence lifespan of the delicate red sea star is remarkably brief, lasting only 24 to 48 hours: within minutes of the egg rupturing, swarms of bluebottle flies, green bottle flies (Calliphoridae), and dung beetles detect the carrion stench, descending onto the red disc to voraciously devour the protein- and sugar-rich gleba. As the insects walk across the scarlet arms and feed, sticky spores adhere to their feet, bristles, and digestive tracts, ensuring wide dispersal as the insects fly throughout the landscape. By the second or third day, with the gleba consumed, the spongy scarlet arms wither, shrivel, and collapse into an odorless residue.

Conservation and Human Impact

Aseroe rubra has not been formally evaluated on the IUCN Red List due to its expansive geographic distribution, high ecological adaptability, and demographic abundance across Australia and New Zealand. Historically, it holds the distinction of being the very first Australian fungus to be scientifically collected and described by European botanists, documented in 1792 by French naturalist Jacques Labillardière in southern Tasmania. Thanks to the global commercial transport of hardwood mulch and garden nursery soil, it has successfully established naturalized populations in Europe, North America, and South Africa. Secure across native forests and cultivated gardens worldwide, it faces zero conservation threats.

Interesting Factoid

The starfish fungus was the first Australian fungus ever discovered by Western scientists; it looks exactly like a bright red sea anemone and smells so much like rotting meat that swarms of flies swarm it within minutes of it bursting out of the ground.