There are 5088 species of jumping spider world wide, 75 in Europe, and 38 in Britain.
The Northern European Salticidae are small and most commonly seen during warm sunny weather. The UK species have black and white, or brown and white stripes, and are active during the day.
Jumping spiders have pads on their feet making it possible for them to cling to smooth surface - even glass.
They have the greatest visual acuity of all arthropods. Their eyes give them binocular vision and they can see in colour and polarized light. The arrangement of eyes is shown below. The pair of small eyes furthest to the back may just detect light and movement.
The spider often rears up to get a better look at things, and they can spot prey 20 cm away. The pair of eyes between the 4 at the front and the two at the rear are hardly visible to the naked eye. The two large front-facing eyes are like headlamps (see left) and do reflect the light just like the eyes of a cat. They stalk prey then leap on it. They have a fondness for leafhoppers, and will eat 4 - 8 per day. Good vision is also needed during courtship.
The male waves his legs and palps semaphore-style as he dances around the female trying to gauge if she is willing to mate. If she is willing to mate his dancing will have reduced her to such a passive state of ecstasy that he can mate and make a retreat with his life; free to delight another girl with the dance of his life and hers.
Salticus sp. The most common species in the genus is Salticus senicus, commonly called the zebra spider because of its stripes. It is often found on walls, fences and window sills during warm, sunny weather. It's body length is 6 - 7 mm when fully grown. Greenfly are a favourite prey of this genus. It mates from May onwards.
The Salticidae move in a jerky fashion making a short, fast run, then stopping to have a look around, and sometimes raising the cephalothorax to get a better view, then another short, fast run.
The photograph below was taken on a wall in my garden. The movement of the fly attracted my attention, but I didn't see the spider at all at first as it was so well camouflaged. As you can see the fly is much bigger and heavier, but was already tiring. The spider just held on to the fly with its fangs and to the stone with its legs and drag line. It was totally oblivious to me, so I could get close enough to take this.