1975] 
Tolbert — Avoidance Behavior in Orb Weavers 
39 
Switching sides of the web 
Switching sides of the web is accomplished when the spider moves 
between the radii in the “free zone” to the other side of the hub. It 
may be followed by web flexing, stilting, or web flexing later fol- 
lowed by stilting ( fig. 4B ) . This response results in the interposition 
of the web as a physical barrier between the orb weaver and a po- 
tential predator. 
Moving away from hub 
When moving away from the hub the spider moves directly away 
from the point of contact: when its eye region is touched, the spider 
moves up the web and if the abdomen is touched, it moves down the 
web. Although one component was often immediately followed by 
another in a single response sequence, individual components were 
usually easy to identify. One exception is when the spider leaves the 
hub while simultaneously flexing the web; it is often impossible to 
tell which is the initial response. In statistical analyses and graphic 
presentations (figs. 4, 5 and 6) web flexing is treated as the initial 
response. This, particular behavioral sequence is unusual in another 
way. Generally web flexing was initiated by rapid spider movement 
which resulted in considerable web movement and a large amplitude 
of web displacement. The response gradually subsided with web 
amplitude decreasing as web and spider movement slowed. In the 
hub leaving-web flexing sequence, however, the spider sometimes 
slowly returned to the hub while web flexing continued. Upon reach- 
ing the hub or shortly thereafter all motion quickly ceased. An ob- 
server has to watch closely to detect spider movement toward the 
hub; this behavior probably serves to distract the predator and then 
hide the orb weaver. 
Rebuff 
Rebuff, as used here, should not be confused with elements of the 
predatory behavior of these species (see Harwood, 1974). It is here 
defined as actively repulsing (pushing away) the model by using any 
of the legs of pairs I or II and/or briefly grasping the model with 
these legs. Biting was never observed although chelicerae were 
sometimes opened and fangs exposed. This may be an intention 
movement and/or threat posture. 
Body flatten 
In a few instances when spiders were approached dorsally, they 
would simply depress their bodies away from the model and flatten 
against the hub. 
