36 
Psyche 
[Vol. 89 
Figure 6. Construction of U. conus web. Sequence of thread attachments in 
forming the cone (web viewed from the side). Arrows indicate direction of movement 
of the spider. Dots are points where attachments were made or broken, (a) The spider 
went to point X on radius R1 at the edge of the hub, cut the radius, attached its 
dragline to the inner broken end and then let out additional dragline as it faced away 
from the hub. This was then attached to the outer broken end which had now moved 
to point Xi. Usually adjacent radii were also broken and attached to radius Ri at 
point Xi (see also Fig. 1). (b) The spider then walked back toward the hub to point 
Y, attached a dragline, ran to the hub and down the central guy thread (G), attaching 
the dragline at point Z. Radius Rl was thus pulled down toward the apex of the cone 
to form the cone radius YZ while the thread HY formed a temporary inner orb 
radius, (c) To move the temporary inner orb radius up on the cone, the spider 
walked out on temporary radius HY and broke it at its attachment to the cone at 
point Y. The spider then attached a dragline to the broken end and walked out on 
radius Rl, reattaching it at point A at the inner edge of the rim sticky spiral. 
(d) The completed cone radius is indicated by line AZ and the new inner orb 
radius by line HA. The section AY of the cone radius bears the cone sticky spiral. The 
upper portion of the guy thread (HZ) was absent in the completed web, but it is not 
known when it was removed. 
After forming the cone, the spider cut most of the temporary 
inner orb radii, thus collapsing the hub and leaving only a bit of silk 
to which a few temporary radii were attached. The spider then 
began replacing these temporary inner orb radii and at the same 
time completing cone formation by incorporating into the cone the 
