210 
Psyche 
[September 
Fig. 1. a) Web of adult female Achaearanea tesselata. Arrow indicates 
position of spider; there is no leaf or other detritus included in the retreat 
of this web. Web platform is about 15 cm across. 
b) Closeup of threads in right edge of platform of the web in a. 
Spaces between threads are larger near the edge of the platform. 
web had only a mesh. One spider kept in captivity built a loose 
mesh on the first night (during which it was apparently disturbed by 
an observation light), added a platform and more mesh on the 
second night (undisturbed), and extended the platform on the third. 
One individual deserted one site in the laboratory and built in 
another. It left the first web intact, indicating that these spiders 
may be unable to re-utilize silk used in previous webs as many a.ra- 
neids do (see Breed et al 1964 for example). Turnbull found that 
Achaearanea tepidariorum also left deserted webs more or less in- 
tact (pers. comm.). 
Attacks on prey 
Achaearajiea tesselata rested in its retreat in the mesh above the 
platform both day and night. A spider’s first response to prey in 
the web was almost always to drop from this position to the under- 
side of the platform. That is, it fell through the platform, but held 
onto it after falling through. These events happened too quickly for 
me to observe how the spider managed to catch the platform as it 
fell through. There was no obvious hole in the platform below the 
shelter either before or after a fall, and spiders could be induced 
to fall through and catch the platform at other points as well. 
When the prey was on the platform, the spider usually rushed 
