The Katipo spider (Latrodectus katipo) is New Zealand’s only native spider capable of delivering a bite dangerously venomous to humans. Belonging to the Latrodectus genus, which includes the black widow and redback spiders, the Katipo is a member of the cobweb spider family. This small arachnid is endemic to New Zealand and is a protected species due to its rarity and declining numbers. The name “Katipo” is derived from the Māori phrase meaning “night-stinger.”
Physical Characteristics and Preferred Location
Sexual dimorphism is distinct in the Katipo, with the female being the medically significant specimen. This is due to her larger size and fangs capable of piercing human skin. The mature female is typically pea-sized, possessing a rounded, black abdomen, though color variations exist. The classic “red Katipo” female, found in the South Island and lower North Island, features a prominent red or orange stripe bordered by white along the top of her abdomen.
A “black Katipo” form is found in the upper North Island, where the red stripe is absent, pale, or replaced with cream-colored blotches. Males and juveniles are much smaller than the adult female and display a different appearance. They are often white with black stripes and red diamond-shaped markings. The male’s smaller size means his fangs are too tiny to pose a threat to people.
The Katipo is strictly restricted to a specialized habitat along New Zealand’s coastlines. These spiders reside almost exclusively within sand dunes near the seashore, preferring the landward side for shelter from strong winds and tides. Webs are often established in low-growing dune vegetation, such as native pīngao or introduced marram grass, or beneath driftwood. They require open patches of sand near their webs for their specific hunting strategy.
Unique Behavior and Conservation Status
The Katipo is a shy, non-aggressive spider, generally preferring to avoid confrontation by retreating or playing dead when disturbed. Bites are exceedingly rare and typically only occur when the female is accidentally trapped against the skin or is defending her egg sacs. The spider constructs an irregular, tangled web close to the ground. This web incorporates a densely woven, opaque silk retreat where the female guards her eggs.
The tangle-web structure includes vertical threads anchored to the substrate, featuring viscid droplets designed to capture ground-dwelling insects like beetles and amphipods. The female lays five or six egg sacs in late spring and early summer, each containing up to 90 eggs, which she guards within her lair. The Katipo’s diet consists mainly of these invertebrates ensnared in the lower parts of her web.
The Katipo is listed as a species in serious decline and is one of the few invertebrates granted “Absolutely Protected” status under New Zealand’s Wildlife Act 1953. This protection reflects the significant threat to its survival, primarily driven by habitat loss. Coastal development and the introduction of exotic sand-binding plants, like marram grass, have reduced the suitable open-sand dune habitat necessary for the Katipo’s web construction.
Invasive species also pose a major threat, particularly the black cobweb spider (Steatoda capensis), often called the False Katipo. This species competes with the native spider for resources and habitat. It is estimated that only a few thousand Katipo spiders remain across a limited number of coastal locations. Conservation efforts focus on managing dune ecosystems and controlling competing invasive species to ensure the survival of this native arachnid.
The Effects of a Bite and Medical Response
A bite from a female Katipo spider injects a neurotoxic venom that causes latrodectism, characterized by severe systemic symptoms. The initial bite may feel like a minor pinprick, but symptoms typically develop and intensify over the following hours. The most common immediate effect is localized pain at the bite site, which quickly spreads and becomes more severe, often radiating to the chest, abdomen, or large muscle groups.
Systemic symptoms of latrodectism include profuse sweating, nausea, vomiting, headache, and hypertension. Muscle rigidity, spasms, and in rare cases, serious complications like myocarditis have been reported. Although bites are rare and no deaths have been reported since the early 20th century, a Katipo bite is considered a medical emergency requiring immediate attention.
Patients who suspect a bite should clean the wound with soap and water and apply a cold compress or ice pack to reduce pain and slow the spread of venom. It is important to avoid applying a pressure bandage, as this is not recommended for neurotoxins. The individual should remain calm and seek urgent medical care.
Treatment often focuses on managing pain with strong analgesics and supportive care. An antivenom is available for severe cases of latrodectism. This antivenom was developed in Australia for the related redback spider (Latrodectus hasselti) but is effective against Katipo venom. It is typically administered intravenously to patients experiencing severe pain and systemic effects, helping to rapidly neutralize the neurotoxins and alleviate symptoms.