Is­land spi­ders dwarf cousins

Each day in Te Papa’s cu­ra­tors tell the story of an in­ter­est­ing item from the mu­seum’s col­lec­tion.

The Dominion Post - - Summer -

The Ran­gatira spi­der is one New Zealand’s largest and rarest arach­nids. Unique to the Chathams, it is found only on is­lands free of in­tro­duced preda­tors, with Ran­gatira Is­land (for which it is named) its main strong­hold.

First dis­cov­ered on Pitt Is­land, th­ese spi­ders have since dis­ap­peared from there, prob­a­bly due to the ar­rival of mice.

They are re­lated to the nurs­ery web spi­ders of main­land New Zealand and are quite sim­i­lar looking. How­ever, they are con­sid­er­ably larger and their 10cm leg span is dou­ble that of their main­land cousins. Like the nurs­ery web spi­der, the fe­male Ran­gatira spi­der builds a spe­cial web to pro­tect her young for a short time af­ter they emerge from their egg sac.

Ran­gatira spi­ders don’t build a web to catch food; in­stead, they ac­tively hunt their prey. Af­ter dark, the leaf lit­ter on Ra- ngatira Is­land seems to come alive with in­sects, pro­vid­ing plenty of op­por­tu­ni­ties for th­ese spi­ders to feed.

One of the back legs of the spi­der in the photo looks dif­fer­ent to the oth­ers. She prob­a­bly lost a leg when younger and grew an­other. As re­place­ment limbs do not reach nor­mal size, one leg is shorter than it should be.

By Phil Sirvid, col­lec­tions man­ager, en­to­mol­ogy.

Photo: MICHAEL HALL/TE PAPA

Rare crea­ture: Ran­gatira spi­der (Dolomedes schauins­landi).

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