The necromorphs can cause, um gashes? on normal humansġ turn people dead or alive in zombies. The flood can cause a spartan to black out in one attack. They can also be stomped/pimp slapped to death by a regular human miner haermm this turns the corspe into a advanced slasher which can take three-four hits with the cutter to take off one off its limbs. if the bat thinks its in danger it will deliver a concentrated dose of the infection into a corpse to protect itself. Re animator bats take only a few seconds to turn a corpse into a necromorph. by they time they open fire a twitcher would have closed the gap in seconds. Standard flood without a weapon usually bludgeons its targets to death using modifications in its arms, this wouldnt be enough to take of limbs, flood with marine weapons would be useless as they cannot take of limbs as well(except for explosives), convent plasma technology may stand a chance but the flood would not be dexterous to concentrate fire on a single limb on a single moving target. the plasma cutter is a piece of mining equipment used to cut up the hardest of materials found in deep space mining, with standard necros it can take two hits with the cutter to take off 1 limb. Issac needed to use a plasma cutter to defeat these bad-asses. if enough limbs are taken off they don't die their body shutdowns to a state where it can be absorbed by a necro growth which can be converted into large fleshy weapons, like the Leviathan.

usually they can function with only 1 limb(will by stopped if only head remains). A standard necromorph will only by stopped if it losses core body mass like arms/legs.

Dead space 2 brute gif