Canadian beaver vs Cobweb weaver

Castor canadensis compared with Steatoda nobilis

Taxonomic Classification

Rank	Canadian beaver	Cobweb weaver
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum	Chordata (Chordates)	Arthropoda (Arthropods)
Class	Mammalia (Mammals)	Arachnida (Arachnids)
Order	Rodentia (Rodents)	Araneae (Araneae)
Family	Castoridae (Beavers)	Theridiidae
Genus	Castor (Beavers)	Steatoda
Species	Castor canadensis	Steatoda nobilis

Evolutionary Relationship

Canadian beaver and Cobweb weaver share a common ancestor at the Kingdom level: Animalia. (Animals)

Conservation Status

Canadian beaver

NE — Not Evaluated

Population: ~15.0M

Trend: Stable →

Cobweb weaver

NE — Not Evaluated

Physical Characteristics

Attribute	Canadian beaver	Cobweb weaver
Diet	Herbivore	—
Average Lifespan	15 years	—
Average Length	1.0 m	—
Average Weight	25.0 kg	—

Habitat & Geographic Range

Canadian beaver

Habitat

Typically found in grasslands, forests, and vegetated habitats.

Range

Widely distributed across Europe (15 countries), North America (United States), and South America (Argentina, Chile).

Cobweb weaver

Habitat

Typically found in terrestrial habitats from forests to deserts.

Range

Widely distributed across Europe (7 countries), North America (United States), and South America (Ecuador).

Canadian beaver

The largest rodent in North America, Canadian beavers weigh up to 32 kg and are master ecosystem engineers inhabiting rivers, lakes, and wetlands across Canada and the northern United States. By felling trees and constructing dams up to hundreds of meters long, beavers create ponds that provide habitat for hundreds of species. Their lodges and canals transform entire watersheds. Once nearly hunted to extinction for their fur, beaver populations have recovered strongly.

Cobweb weaver

The noble false widow (Steatoda nobilis) is a theridiid spider that has attracted considerable media attention in the British Isles and along the Atlantic coast of Europe due to its painful but rarely dangerous bite and its rapid range expansion facilitated by human activity. Originally native to the Canary Islands and Madeira, the species arrived in southern England during the 19th century, likely via banana shipments, and has since spread northward through Britain and westward into Ireland, while also establishing populations along the Iberian Peninsula and Atlantic France. Females are robust, with a dark brown carapace and a distinctive cream-colored pattern on the bulbous abdomen that varies between individuals; females reach 8.5–14 millimeters in body length, making this one of the larger European theridiids. The species constructs persistent, tangled cobwebs in sheltered locations outside buildings—under window ledges, in door frames, and in garden walls—as well as within homes in cooler seasons. It is a generalist predator, capturing insects and other invertebrates, and has been reported to occasionally subdue prey considerably larger than itself, including small lizards. Steatoda nobilis venom produces steatodism, which can cause localized pain, swelling, and in rare cases systemic symptoms. Its conservation status has not been formally assessed, but its expanding range demonstrates considerable resilience.

Shared Countries

Both species can be found in 6 countries:

🇧🇪 Belgium 🇫🇷 France 🇳🇱 Netherlands 🇵🇹 Portugal 🇬🇧 United Kingdom 🇺🇸 United States