Cigar shark vs Coastal Mushoom

Isistius brasiliensis compared with Agaricus litoralis

Taxonomic Classification

Rank	Cigar shark	Coastal Mushoom
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	Agaricus (Button Mushrooms)
Species	Isistius brasiliensis	Agaricus litoralis

Conservation Status

Cigar shark

LC — Least Concern

Coastal Mushoom

LC — Least Concern

Physical Characteristics

Attribute	Cigar shark	Coastal Mushoom
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

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.

Coastal Mushoom

Habitat

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

Range

Distributed across Belgium, Denmark, Norway, and Sweden.

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.

Coastal Mushoom

Agaricus litoralis, the coastal mushroom, is a saprotrophic agaric fungus in the family Agaricaceae occurring in sand dunes, coastal grassland, and sandy soil habitats along the coasts of northwestern Europe, with confirmed records from Belgium, Denmark, Norway, and Sweden. The genus Agaricus contains the familiar cultivated button mushroom (A. bisporus) along with hundreds of wild species, and members are characterized by a ring on the stem and browning, discoloring, or non-discoloring flesh when cut, features used in field identification. Agaricus litoralis is a medium-sized mushroom producing white to cream-colored caps 4–10 centimeters across with pinkish then dark brown gills and a stout stem with a double ring, fruiting in sand dune hollows and the grassy margins of coastal habitats from summer through autumn. The specific epithet litoralis refers directly to its coastal habitat preference. As a saprotroph, it decomposes organic matter in the sandy soil substrate, releasing nutrients back into the ecosystem. The species is classified as Least Concern by the IUCN, being relatively widespread in suitable coastal sandy habitat across northwestern Europe. Like many coastal fungi, it is specifically adapted to the nutrient-poor, well-drained, alkaline conditions of stabilized sand dune systems.