Cited research: J. Exp. Biol. 213, 2372–2378 (2010)

Jumping spiders have exceptional eyesight compared with other creatures of their size, but biologists may have underestimated the visual acuity of one of their pairs of eyes.

The spiders have a principal pair that faces forwards and has excellent resolution but a very narrow field of view, and two or three secondary pairs that detect motion over a wider field. Daniel Zurek and his colleagues at Macquarie University in Sydney, Australia, used dental silicone to cover all but one pair of eyes — the set of secondary ones that faces forwards — in 52 jumping spiders (Servaea vestita). They then presented the arachnids with moving dots on a screen, and with live, tethered house flies, the spiders' favoured prey.

The spiders oriented themselves in the direction of the dots and began stalking the flies. This pair of secondary eyes, the authors say, may be the most versatile element of the creatures' visual system, providing both spatial acuity and motion detection. J.F.

Credit: X. J. NELSON