I think the feeding part was not done justice when it was depicted. Take note that the feeders are insanely fast, and as such I assume they attack and bite just as quickly. Imagine having a rat biting on your arm, and it can bite 10 times a second (I exaggerate, but they should be quite fast). I imagine 2 of those can easily sever your limbs after a few tries.

The manga freeze panels simply could not show the ferocity of the feeding frenzy that occurred.