| This photo of a
female Arrow Shaped Micrathena was taken at
Burgess Falls State Natural Area in Tennessee in early August.
Males of this species grow to about 1/4" while the females can grow to
3/8". While both sexes have the twin spines at the rear of the abdomen, the
females also have spikes on their backs. One of the spikes of this female are
barely visible on the left hand side ( as viewed) of its abdomen.