 They possess 8 eyes and are known to
have the sharpest vision of all
spiders, important for hunting
ability. The arrangement of the
eyes,
four big eyes on the face and
four
smaller eyes on top of the
head,
distinguished Saltids from other
spiders.(3) The larger pair of eyes
(anterior median on the face)
apparently serve for sharp vision,
and the others for peripheral
vision.
Since the lenses of these
eyes are
relatively fixed, the
internal eye
muscles serve to move
the retina.
Because the retina is
the darkest
part of the eye and it
moves around,
one can sometimes look
into the eye
of a jumping spider and
see it
changing color. When it is darkest,
you are looking into its retina and
the spider is looking straight at
you.(4)
These spiders apparently have
dichromic vision with spectral
sensitivities in the green and
ultraviolet range.(5) (Ultraviolet
vision is apparently common in the
insect and arachnid world.) They
depend much upon their sense of
sight
to hunt or to court. It is
apparently
for this reason that many jumping
spiders have iridescent markings or
colors on their bodies,
legs and chelicerae. In P. audax,
the chelicerae are iridescent
green.(6)
Jumping spiders are carnivores and
predators. They eat insects and
other spiders. These spiders do not
spin webs but make little silken
shelters under leaves or bark.(1)
Saltids are the most common biting
spider in the United States.(7)
Persons gardening appear to be at
risk for disturbing the habitat of
this spider which may react by
jumping on exposed skin and
inflicting a bite. The bite is
usually asymptomatic to slightly
painful and subsequently results in
a local reaction such as an
erythematous papule or a small
urticarial wheal.
REFERENCES
1. Jumping Spiders (Family Salticidae) in Lorus and Margery Milne, The Audubon
Society Field Guide to North American Insects and Spiders. Alfred A. Knopf, New
York, 1980. page 910
2. Richman David B. Status of Jumping Spider (Araneae Salticidae) Taxonomy
worldwide. http://dns.ufsia.ac.be/Arachnology/Pages/Documents/Salticid.html
3. Saltids.
http://spiders.arizona.edu/salticidae/salticidae.html
4. Wayne
Maddison Jumping spider vision.
http://spiders.arizona.edu/salticidae/
++salticidae/anatomy/vision.html
5. De Voe RD. Ultraviolet and green receptors in principal eyes of jumping
spiders. Journal of General Physiology, 1975 Aug, 66(2):193-207.
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