Which two systems most directly interact in the fuzzy millipede's defense against ants?

Two systems most directly interact in the fuzzy millipede's defense against ants are:

muscular and integumentary

Explanation:

The fuzzy millipede, Polyxenus fasciculatus, is found in Texas and is preyed upon by most species of ants. Most millipedes defend themselves with a variety of chemicals secreted from pores along the body, although the tiny bristle millipedes are covered with tufts of detachable bristles. Due to their lack of speed and their inability to bite or sting, millipedes' primary defence mechanism is to curl into a tight coil - protecting their delicate legs inside an armoured exoskeleton. Reproduction in most species is carried out by modified male legs called gonopods, which transfer packets of sperm to females. Millipedes overwinter, so they may hide in cracks or crevices throughout the whole winter and emerge in the spring. These insects live in dark, damp places and feed on decaying plant life, sometimes damaging crops. But they can serve a good purpose too. To protect itself against the ants, it ejects fibers from a tuft located at the tail end of its body. When an ant attacks, the millipede flexes its back end toward the ant and wipes the tufts against it.