Crawler can be used in two ways: by ripping off all of its legs and throwing the abdomen, it becomes like a grenade which explodes after a couple of seconds. Ripping off just one leg and throwing will make the crawler become like a proximity mine; attaching to whatever surface it lands on and exploding when a creature comes near. Pressing secondary fire makes Tommy flip the Crawler over to select which way to use it.
Grenades can be delayed, by holding primary fire button. However, there is a time out, after which crawler will explode in Tommy's hand.
Crawlers look like green, three legged insects with a small mouth and four glowing eyes.