Cigar shark vs Eurasian beaver

Isistius brasiliensis compared with Castor fiber

Key Differences

• Cigar shark is Least Concern while Eurasian beaver is Vulnerable.

Taxonomic Classification

Rank	Cigar shark	Eurasian beaver
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum same	Chordata (Chordates)	Chordata (Chordates)
Class	Elasmobranchii	Mammalia (Mammals)
Order	Squaliformes (Squaliformes)	Rodentia (Rodents)
Family	Dalatiidae	Castoridae (Beavers)
Genus	Isistius	Castor (Beavers)
Species	Isistius brasiliensis	Castor fiber

Evolutionary Relationship

Cigar shark and Eurasian beaver share a common ancestor at the Phylum level: Chordata. (Chordates)

Conservation Status

Cigar shark

LC — Least Concern

Eurasian beaver

VU — Vulnerable

Physical Characteristics

Attribute	Cigar shark	Eurasian beaver
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.

Eurasian beaver

Habitat

Typically found in diverse terrestrial and aquatic ecosystems.

Range

Found across Europe (6 countries). Currently classified as Vulnerable on the IUCN Red List, this species faces significant conservation challenges across its range.

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.

Eurasian beaver

Eurasian beaver (Castor fiber) is classified as Vulnerable (VU) on the IUCN Red List. Facing a high risk of endangerment in the wild, with declining populations and increasing habitat pressure.

Shared Countries

Both species can be found in 1 countries:

🇳🇴 Norway