New Zealand, celebrated for its unique biodiversity, often prompts questions about the size of its spider inhabitants. Its isolated evolution has led to a fascinating array of arachnids. While encountering immense spiders can be unsettling, the reality in New Zealand offers a different perspective on what constitutes a “big” spider.
What Constitutes a “Big” Spider in New Zealand?
When defining a “big” spider in New Zealand, it’s important to adjust expectations often shaped by perceptions of tropical regions. Unlike tarantulas found globally, New Zealand does not host spiders of comparable immense size. While some species are notably larger than common household spiders, they do not reach the formidable dimensions seen in warmer, more humid climates. New Zealand’s larger spiders are impressive within their local context, but are generally not comparable to the largest arachnids globally.
What a visitor might consider “big” could be significantly different from the actual maximum sizes of spiders native to or established in New Zealand. Their “largeness” often refers to a body length of several centimeters or a leg span that can span several inches. These dimensions differentiate them from smaller, more common spider species found throughout the country.
Notable Larger Spider Species
Several spider species in New Zealand stand out due to their larger size. The Avondale spider, Delena cancerides, is an introduced huntsman from Australia, commonly found in the Auckland region. Females can reach a body length of 25-32 millimeters, with males slightly smaller. Their leg span can extend over 15 centimeters, sometimes up to 20 centimeters, making them visually striking. These spiders typically have a light brown, hairy body.
The nursery web spider, Dolomedes minor, is a native species found throughout New Zealand. Females can have a body length of around 18 millimeters, and their leg span can exceed 60 millimeters. They are pale brown to grey, which helps them blend into their surroundings. The black tunnelweb spider, Porrhothele antipodiana, is an endemic native spider widely distributed across the country. Its body can reach up to 30 millimeters in length, with a leg span of approximately 50 millimeters. This spider has a reddish-brown cephalothorax and dark abdomen and legs, with noticeable spinnerets.
The Nelson cave spider, Spelungula cavernicola, holds the record for the largest leg span among New Zealand spiders, reaching up to 13 centimeters, with a body length of about 3 centimeters. This species is restricted to cave environments in the Nelson region.
Understanding Their Behavior and Habitat
Larger spiders in New Zealand exhibit diverse behaviors and occupy various habitats. The Avondale spider, for instance, is primarily nocturnal, seeking refuge during the day in dark, dry locations such as attics, sheds, garages, or under loose tree bark. They are active hunters, pursuing prey rather than relying on webs. Unusually for spiders, Avondale spiders are social and can live in large colonies, sometimes numbering up to 300 individuals.
The native nursery web spider is widespread and can be found in a variety of environments, including shrubland, swamps, grasslands, and particularly near bodies of water. These spiders are nocturnal hunters and possess the unique ability to walk on water surfaces. Female nursery web spiders are known for constructing distinctive “nursery webs” on shrubs to protect their eggs and spiderlings.
Black tunnelweb spiders are common in both native bush and urban gardens. They construct silk-lined tunnels under objects like logs, rocks, or within rock walls and basements. At night, they wait near the entrance of their tunnel and ambush unsuspecting prey that triggers vibrations on their web. During spring and summer, male tunnelweb spiders are often seen roaming, searching for females. Most of these larger spiders are generally shy and prefer to avoid human contact, playing a role in their ecosystems by controlling insect populations.
Are New Zealand’s Larger Spiders Dangerous?
Despite their sometimes imposing size, the larger spider species found in New Zealand are generally not considered dangerous to humans. The venom of these larger species typically poses little threat. The Avondale spider, while large and occasionally startling, is regarded as harmless to humans. Bites from this species are infrequent and, if they occur, usually result in only minor symptoms.
The nursery web spider presents minimal health risks to humans. Bites are rare and usually happen only if the spider is provoked or accidentally handled. While a bite might cause mild discomfort, it is not considered life-threatening, and medical treatment is typically not required. The venom of the nursery web spider is mild, primarily effective against its insect prey and small animals.
The black tunnelweb spider, with its larger fangs, can deliver a painful bite. However, the effects of its venom are generally mild, often compared to the sensation of a bee sting, causing localized swelling, itching, or numbness. If a bite occurs, cleaning the area is advisable to prevent secondary infection. While New Zealand has a few medically significant spiders, such as the native katipÅ and introduced redback and white-tailed spiders, these are generally smaller species and are not the “big spiders” that often capture public attention.