There are a few animals with special defenses against tug worms. One is the row bug. Row bugs sometimes resemble pill bugs or sow bugs from Earth except that they have four rows of legs instead of two, each leg ending in grasping fingers. Some can grow as long as three meters. To eat, they grasp food in their fingers and bring it up to the mouth. Since their legs hold their bodies so high above the reef, the tug worms cannot reach them except for the legs. If a row bug happens to step in a tug worm nest while grazing, it simply detaches the affected leg and lets the tug worms have it. Row bugs have so many legs, they rarely miss any.
The species of row bug depicted in the diagram has twenty-four legs. Only the frontmost four are shown. This species has longer fingers than most. It has four backbones (one for each row of legs), two mouths, and two digestive tracts. The green spots are ears. They connect to ganglia at the anterior ends of the outer two backbones.