7 things you didn’t know about the zebra jumping spider

 from BBC Wildlife  July 16, 2015
Zebra jumping spider

1. Urban warriors

These striking little jumping spiders are most frequent around human habitations – on sunny outside walls and fences and sometimes indoors. But they also turn up on tree trunks, rocks and shingle.

2. Dark arts

The contrast between the black and white stripes is rather variable. Entirely black forms have been recorded in industrially polluted areas, where they are better camouflaged against sooty surfaces.

3. Hydraulic jump

They jump by explosively straightening their back legs. Lacking extensor muscles, the legs are powered by the pressure created when blood is pumped into them from the body.

4. Eyes front

They track moving prey with binocular vision provided by a pair of enormous forward-facing eyes. These can swivel up and down and side to side and move forward and back to focus.

5. Backward looking

Six smaller, fixed eyes detect movement to the sides and rear. Waggle a finger behind them and they will spin round to take a closer look.

6. Long in the tooth

Adult males can be recognized by their massive, elongated chelicerae (the mouthparts that bear the fangs), which they wield during tussles with other males.

7. Drag act 

The safety lines they trail behind them can hold a fall only if the plummeting spider releases more silk through its spinnerets to reduce the shock-load on the thread.