20th International Congress of Arachnology

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should have limited color discrimination abilities based
on a system of UV-green dichromacy, and should therefore
lack the ability to discriminate long wavelength colors
such as yellows or reds. Here, we present evidence for two
independent, functionally distinct evolutionary origins of
color vision in the Salticidae: filter-based trichromacy in
the colorful Habronattus jumping spiders of North and
Central America, and non-filter-based tetrachromacy in the
Australian “peacock” spiders of the genus Maratus. Using
a combination of microspectrophotometry, histology, and
visual system modeling, we characterize the sensitivities
of these novel color vision systems and describe how they
might have enabled the evolution of a wider gamut of
male courtship coloration in these two spider groups.
Keywords: visual ecology, color vision, sexual selection,
speciation
Student - poster presentation
Effects of starvation on foraging behavior
in the scorpion Tityus serrulatus (Buthidae)
Gabriel Pimenta Murayama, Rodrigo Hirata Willemart
Rua do Matão, travessa 14, n. 101, CEP 05508-090,
São Paulo-SP, Brazil
Starvation is known to affect foraging and sensory perfor-
mance in animals. Under starvation conditions, animals
may change their foraging strategy (wandering more),
become more generalist, become risk-prone and increase
their sensory perception. In scorpions, it has been shown
that starvation affects the physiologic state, but few works
have tested how this condition affects foraging behavior. We
hypothesized that starved scorpions change from sit-and-
wait to roving and that the threshold for prey detection is
decreased. To assess changes in the foraging strategy, we
divided an arena (45.3 x 33.3 x 13.3cm) in 12 quadrants of
11.3 x 11.1 cm and quantified the total number of quad-
rants used, the number of quadrant changes and whether
the scorpion was walking or motionless in each sampling.
No prey was present during the trials. We compared scorpi-
ons starved 30 days with scorpions fed once a week before
the experiment. To assess changes in the threshold for prey
detection, we measured the distance (ongoing analysis) and
latency to detect crickets. We also looked at differences in
specific behaviors between treatments (ongoing analysis).
We found no differences between treatments in any of the
measured variables so far. Perhaps the starvation period
was not long enough and/or differences appear in other
behaviors that we did not measure, such as ingestion time.
Keywords: hunger level, prey detection, foraging strat-
egy, sit-and-wait
Student - poster presentation
The importance of trichobothria in prey-
capture success in the scorpion Tityus
serrulatus(Buthidae)
*Gabriel Pimenta Murayama, Rodrigo Hirata Willemart
Rua do Matão, travessa 14, n. 101, Cidade Universi-
taria, São Paulo, SP 05508-090, Brazil
Arachnids often rely on substrate-borne vibrations
and air displacement to detect prey. These stimuli are
detected by organs such as slit sensilla and trichoboth-
ria. We tested the hypothesis that trichobothria on the
pedipalps are important for capturing prey in scorpi-
ons. We predicted that scorpions with trichobothria
removed would have a lower prey-capture success rate
than control groups (other setae removed/no setae
removed). We first anesthetized scorpions in the freezer
and cut all trichobothria on the pedipalps except those
of the inner region of the femur because these were
difficult to access. We then released a scorpion and an
immature cricket without legs III in a circular arena
with suspended filter paper in the bottom We measured
prey-capture success as the number of scorpions that
held the cricket for more than 2 s and, within the group
that captured prey, the number of capture attempts. We
also tried to find differences between the three treat-
ment groups in the latency to detect prey, latency to the
first attack and in the number of times each animal
rotated to face the prey. We found no differences in
any of the variables measured. Scorpions are known to
possess other sensory organs (basitarsal compound slit
sensillum and tarsal hairs) that allow them to detect
prey by substrate vibration. These organs may have
144 DENVER MUSEUM OF NATURE & SCIENCE REPORTS | No. 3, July 2, 2016
Cushing