(BG) Arrowhead Spider (Verrucosa arenata) 4-5mm 6/22/12 PL DE (see description)

(BG) Arrowhead Spider (Verrucosa arenata) 4-5mm 6/22/12 PL DE (see description) On Swamp Black Gum (Nyssa sylvatica var. biflora)

Am curious to know what the purpose of the "trampoline" might be
and whether or not the spider made the hole.

In the second picture it's busy working at the webbing of the hole.
Whether it was making, repairing, or eating it (to make room to
escape from me), I guess I'll never know.

info:
http://bugguide.net/node/view/2035

http://bugguide.net/node/view/662112/bgimage