8 
Psyche 
[March 
but attacks from above the dorsal surface of the araneid were 
successful in all cases. (Eventually, all four A argentataw/ere killed.) 
In all cases, the araneids jumped off the hub when the Phiale con- 
tacted them. At the cage floor they moved about but could not 
displace the salticid and were eventually pulled up the cage wall 
to a feeding site. 
The conditions in the cages probably made the attacks easier 
than they would be in field conditions. The Argiope web was 
surrounded by a continuous rigid surface on all sides. In the field 
the salticid must have to rely on discrete vegetation units for origi- 
nating its attacks and though it can jump from plant to plant until 
it finds a suitable site, it may not be able to keep the spider in 
view continuously. In the cages the salticids looked at the Argiope 
from the cage floor, the cage walls and even the cage roof, before 
eventually lining up on the wall to launch an attack. Where it was 
possible to gauge the point of origin of attacks with some accur- 
acy, they seemed to occur from a position only slightly above 
the point horizontally opposite the spider. When launching attacks 
off the glass sides of cages, the salticid turned around several 
times before jumping. Subsequent examination showed several 
silk attachments on the glass in this region. This suggests that 
the spider may make multiple dragline attachments before long 
aerial attacks. Take off postures were always head down (i.e. 
with the cephalothorax lowermost but strongly angled towards 
the target, and with legs I off the substrate). 
These observations made on a small sample in simplified con- 
ditions show that an attack on the dorsal surface of a large prey 
item can be very successful. Movement seems to be necessary 
for the initiation of hunting behavior, but attacks were made on 
subsequently motionless prey. The salticids made accurate dis- 
tance terminations and traversed horizontal distances measured 
at greater than 12cm. The failure of attacks made from the ‘wrong 
side of the hub’ (i.e. with the web between the salticid and the 
araneid) suggest that the behavior of shuttling (= switching sides 
of the web, Tolbert 1975), may be an effective defense, as argued 
by Robinson & Robinson (1970). Dropping from the web clearly 
did not aid the araneid in the experimental situation but could 
help in defense against salticids in a more natural one. The araneid 
might be able to brush off its attacker against the vegetation be- 
low the web. It can clearly work in other contexts against other 
predators. 
