Brilliant Jumping Spider

Appearance

Like other jumping spiders, it has vision more acute than a cat and ten times more acute than a dragonfly. The eyes are used to locate prey and rivals, and find and court mates. All spiders have sensors for smell, taste, touch and vibration protruding through their cuticle.

Jumping spiders can leap up to 50 times their own length by powerfully extending the third or fourth pairs of legs, with the longer forelimbs extended to grasp the prey. ''P. clarus'', a relatively large salticid, takes prey up to the size of an adult earwig. In an experiment, ''P. clarus'' was offered as many fruit flies as it could eat, and in four-hour sessions individuals took 17 flies on average – while one took 41.

Naming

The spider is one of 60 species in the genus ''Phidippus'', and one of about 5,000 in the Salticidae, a family that accounts for about 10% of all spider species. ''P. clarus'' is a predator, mostly taking insects, other spiders, and other terrestrial arthropods.

Habitat

''Phidippus clarus'' is found in old fields throughout eastern North America. It lives among flowers, often sharing habitats with the small to medium-sized crab spider ''Misumena vatia'', which waits for prey. ''P. clarus'' often waits upside down near the top of a plant, a position which may be useful for detecting prey and then quickly jumping down before the prey can escape. In a 2002 survey of jumping spiders in Minnesota, ''P. clarus'' accounted for 52% of the total found.

The Californian wasp ''Aporinellus completus'' parasitizes ''P. clarus'' by paralyzing the spider and attaching an egg to the spider's abdomen. Mermithid nematodes infest ''P. clarus'' and many other spiders, typically severely damaging the main muscles, the digestive system and the reproductive system.

Reproduction

''Phidippus clarus'' becomes adult in early summer, and females about to lay eggs can weight 400 milligrams. Early in the breeding season, in early to mid July, there are more males than females. The females all become sexually mature at the same time. At this point during this part of the breeding season males die off, so that the number of males becomes equal or slightly smaller than the number of females. By August, most females live in their nests overnight for increasing periods, as this is where they will lay eggs. The nests are located in rolled up leaves and are made of thick silk, which is expensive to build. Tests show that females use visual landmarks to return to their nests. A male only remains at the same nest when paired with a female.

Before looking for a mate, a male spider spins a small, flat web on a surface and ejaculates into it. He then loads the semen into syringe-like receptacles in both palps, and then searches for a female.

Like other spiders and many other arthropods, ''P. clarus'' can vibrate surfaces to interact with others of its species, sometimes in conjunction with other communications such as movements, to intimidate rivals and woo mates.

Food

Almost all jumping spiders are predators, mostly preying on insects, other spiders, and other non-aquatic arthropods. The most common procedure is sighting the prey, stalking, fastening a silk safety line to the surface, using the two pairs of back legs to jump on the victim, and finally biting the prey. Most jumping spiders walk throughout the day, so that they maximize their chances of a catch.

After capturing the prey, ''P. clarus'' settles in one spot and does not move again until it has discarded the undigestible hard remains of the prey. If ''P. clarus'' has gone without food for a few days, it eats slowly.

''P. clarus'', which is large by the standards of salticids, takes prey up to the size of an adult earwig. In an experiment, the jumping spider was offered as many fruit flies as it could eat, and in 4-hour sessions specimens took 17 flies on average—while one took 41. When the courtship display of wolf spider ''Schizocosa ocreata'' combines visual signals with vibrations, ''P. clarus'' responds to its wolf spider prey more quickly than when the wolf spider presents only one of the types of signal.