July 09, 2012

Jumping Spider

Jumping spiders are among the easiest to distinguish from similar spider families because of the shape of the cephalothorax and their eye patterns. Jumping Spider's possess the unique ability to jump or pounce onto their prey. They are distinguished by their unique eye structure, usually composed of two rows.
Their eye pattern is the clearest single identifying characteristic. Most diagnostic are the front row of four eyes, in which the anterior median pair are more dramatically prominent than any other spider eyes apart from the posterior median eyes of the Deinopidae. There is however a radical functional difference between the major (AME) eyes of Salticidae and the major (PME) eyes of the Deinopidae; They have eight eyes, as illustrated.; The large posterior eyes of Deinopidae are adapted mainly to vision in dim light, whereas the large anterior eyes of Salticidae are adapted to detailed three-dimensional vision for purposes of estimating the range, direction, and nature of potential prey, permitting the spider to direct its attacking leaps with great precision.
The rear row of four eyes may be described as strongly bent, or as being rearranged into two rows, with two large posterior lateral eyes furthest back. They serve for lateral vision. The posterior median eyes also have been shifted out laterally, almost as far as the posterior lateral eyes. They are usually much smaller than the posterior lateral eyes and there is doubt about whether they are at all functional in many species.
Jumping spiders range in size from a body length of 1 mm to 22 mm. The spidy got used to my lens and started posing as like this:

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