The answer to whether Iceland has spiders is an unequivocal yes. This reality often contrasts with the common perception that the country is largely spider-free due to its isolated, subarctic environment. While spiders certainly exist, the species found in Iceland are overwhelmingly small and harmless, generally avoiding the large, conspicuous presence seen in warmer climates.
Native and Common Species
Iceland is home to approximately 84 recorded spider species, a number low compared to continental Europe but typical for a remote, northern island. The most common families include the Linyphiidae, commonly known as sheet weavers or money spiders. These spiders are numerous but very small, typically measuring only 1 to 3 millimeters in body length. They often disperse through “ballooning,” using silk threads to travel on wind currents, which helped many species colonize the island.
Wolf spiders (family Lycosidae) represent another significant native group. These are active hunters that do not build webs, instead utilizing habitats like heathlands, grasslands, and lava fields. The Common House Spider, Parasteatoda tepidariorum, is also found indoors. This species is tiny, with a body length ranging from 4 to 6 millimeters, and is a member of the cobweb spider family (Theridiidae).
The Role of Iceland’s Climate
The limited number of spider species and their small size result directly from Iceland’s unique geographic and climatic history. The island’s position in the North Atlantic and its relatively recent geological formation, combined with the effects of the last glacial period, severely restricted initial colonization by terrestrial arthropods. The subsequent oceanic climate, characterized by cool temperatures and a short growing season, limits the resources and time needed for larger species to complete their life cycles.
The low biodiversity reflects the challenges of crossing vast oceanic distances to reach the island. Established populations were typically those with high dispersal capabilities, such as the ballooning ability of the Linyphiidae. This harsh environmental filter means Iceland lacks the diverse, large, and medically significant venomous spiders found in warmer, more connected landmasses. The cold environment selects for smaller, hardier species capable of surviving in limited niches.
Addressing the ‘Big Spider’ Question
The rare sighting of a noticeably large spider in Iceland is almost always the result of accidental importation, rather than a native population. These larger specimens are known as stowaways, arriving via international cargo, produce shipments, or shipping containers. They are non-native species that struggle to establish self-sustaining populations in the harsh Icelandic outdoors.
The most prominent example is the Giant House Spider, Eratigena atrica. Females can reach a body length of up to 18 millimeters, with a leg span that can exceed 75 millimeters in the male, making it a startling sight indoors. Despite its size and speed, this species is not considered dangerous to humans and is reluctant to bite. These rare encounters are not endemic to Iceland and do not possess venom of medical importance.