Katipo - Habitat

Habitat

The katipo is restricted to a highly specialised habitat and is only found near the seashore living among sand dunes. They generally reside on the landward side of dunes closest to the coast where they are most sheltered from storms and sand movement. They can sometimes be associated with dunes several kilometres from the sea when these dunes extend inland for long distances.

Webs are typically established in low-growing dune plants and other vegetation such as the native Pingao (Desmoschoenus spiralis) or the introduced marram grass (Ammophila arenaria). They may also build their webs under driftwood, stones, or other debris such as empty tin cans or bottles. Webs are almost always constructed over open sand and near the ground so as to catch crawling insects for food. Spiders inhabiting dune grasses construct their webs in open spaces between the grass tufts, while spiders inhabiting areas of shrubbery do so on the underside of a plant overhanging open sand. It has been found that these patches of open sand are necessary for katipo to build their webs as plants that envelop sand dunes in dense cover, such as exotic plants like kikuyu or buffalo grass, create an environment unsuitable for web construction. The katipo therefore prefers to spin its web amongst pingao plants as this plants growth pattern leaves patches of sand between each plant. The wind can then blow insects and other prey through these gaps and into the web. Marram grass has been extensively planted in New Zealand to help stabilise sand dunes and has largely replaced pingao in many areas. Because marram grass grows in a very tight formation only leaving small gaps between tuffs, this makes it difficult for the katipo to construct a suitable web for capturing prey.

Like other theridiid spiders, the web is a disorganised, irregular tangle of fine textured silk. It is hammock-shaped and is made up of opaque yellowish-white silk. The web consists of a broad base with many supporting threads above and below, including a number of sticky guy lines anchored to debris in the sand. A cone-shaped retreat is built in the lower part of the web, although the katipo can normally be found near the main body of the web. The plants it builds its web in provide support and shelter for the nest.