Arachnophobes rejoice - new research shows the critters you fear the most have their own phobias.

A University of Canterbury researcher said most spiders were terrified of ants and even "run for their lives" in fear of a jumping spider that pretends to be an ant.

Spider and ant expert Dr Ximena Nelson said more than 300 species of spider have evolved to mimic ants other spiders feared.

The jumping spider myrmarachne melanotarsa looks like, acts like, and hangs out with ants. Dr Nelson said it even formed "mini colony-type gangs" to thwart predators. "But most spiders are afraid of ants, and they even fear these fake ants that are really spiders," Dr Nelson said.

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Dr Nelson, a spider and ant expert, believed the jumping spider evolved its ant-like ways in which each morph that resembled ants more was selected for and morphs that did not resemble ants were selected against.

The deception worked better if the fake ant behaved like an actual ant too. "Ants are social and can mount a strong response if alerted to potential danger. They are extremely lethal to many spiders. Many ants also contain formic acid, which they can use for defence by squirting it on potential predators, causing considerable harm," Dr Nelson said.

Only a few spiders were "ant specialists" that routinely consumed ants. "These species typically have venom or behavioural modifications that enable them to cope with ants. It has been suggested that the webs of Australian red back spiders are designed to catch ants," Dr Nelson said.

According to Te Papa, about 35,000 to 40,000 species of spider were known to scientists. The national museum said in New Zealand, around 1100 species were discovered, and 95 per cent of them were found nowhere else on earth.