Each nettle tentacle is coated with thousands of microscopic nematocysts; in turn, every individual nematocyst has a "trigger" (cnidocil) paired with a capsule containing a coiled stinging filament. Upon contact, the cnidocil will immediately initiate a process which ejects the venom-coated filament from its capsule and into the target. This will inject toxins capable of killing smaller prey or stunning perceived predators. On humans, this will most likely cause a nonlethal, but painful stinging sensation which can last for forty minutes. In addition, the black sea nettle's stomach is lined with a fibrous network of vessels that attach themselves to a swallowed victim and darkmaws for quick digestion or breaking apart large prey, though the maws will close when exposed to bright lights, hence their name.