Cigar shark vs Fly Agaric

Isistius brasiliensis compared with Amanita muscaria

Taxonomic Classification

Rank	Cigar shark	Fly Agaric
Kingdom	Animalia (Animals)	Fungi (Fungi)
Phylum	Chordata (Chordates)	Basidiomycota (Club Fungi)
Class	Elasmobranchii	Agaricomycetes (Mushrooms)
Order	Squaliformes (Squaliformes)	Agaricales (Gilled Mushrooms)
Family	Dalatiidae	Agaricaceae (Agarics)
Genus	Isistius	Amanita (Amanitas)
Species	Isistius brasiliensis	Amanita muscaria

Conservation Status

Cigar shark

LC — Least Concern

Fly Agaric

LC — Least Concern

Trend: Stable →

Physical Characteristics

Attribute	Cigar shark	Fly Agaric
Diet	—	Decomposer
Average Lifespan	—	1 years
Average Length	—	20 cm
Average Weight	—	100 g

Habitat & Geographic Range

Cigar shark

Habitat

Native to Asia and Europe and South America, inhabiting ecosystems characteristic of the region.

Range

Distributed across Chile, Norway, and Taiwan.

Fly Agaric

Habitat

Typically found in forest floors, decomposing wood, and soil ecosystems.

Range

Widely distributed across Europe (4 countries), North America (United States), Oceania and the Pacific (New Zealand), and South America (Brazil, Chile, Colombia).

Cigar shark

The cigar shark, also known as the cookiecutter shark (Isistius brasiliensis), is a small but remarkable shark in the family Dalatiidae, found throughout warm oceanic waters worldwide in tropical and subtropical latitudes. Reaching only 40–50 centimeters in length, it possesses oversized jaws with large, triangular lower teeth arranged in a saw-like series that cut distinctive circular plugs of flesh from much larger prey—including tuna, dolphins, whales, billfish, and even submarine cables and human bodies. It does not kill its prey but instead latches on, rotates its body, and excises a characteristic cookie-cutter-shaped bite. The cigar shark is bioluminescent, emitting a green glow from photophores on its ventral surface that may serve as counter-illumination or to attract prey from below. It undertakes diel vertical migrations, ascending to shallower waters at night and descending to mesopelagic depths during the day. The species is classified as Least Concern by the IUCN, with a vast oceanic distribution and no targeted commercial fishery. It is occasionally taken as bycatch. The geographic epithet brasiliensis refers to Brazil, where early specimens were described, but the species' range is circumglobal in warm oceans. The cookiecutter shark's feeding strategy is one of the most unusual among elasmobranchs.

Fly Agaric

Among the most iconic and recognizable fungi on Earth, fly agaric mushrooms display striking red caps with white flecked warts across boreal forests of the Northern Hemisphere. Despite their fairy-tale appearance, they contain potent psychoactive compounds including muscimol and ibotenic acid and are moderately toxic. They form critical mycorrhizal symbioses with birch, pine, and spruce trees, exchanging mineral nutrients for carbon and playing essential roles in boreal forest nutrient cycling.