The crawler is a variation of the zombie that crawls on the ground, it burns in daylight and attacks villagers like a normal zombie.
The crawler looks like a zombie model turned on it's stomach, but with it's arms out in front of it and it's head looking directly forward (which would be strait up on a normal zombie.
The crawler moves slower than a normal zombie, and is as slow as a zombie with Slowness I. The crawler has only 15 health, but does the same amount of damage as a zombie.
The crawler also has a baby and zombie villager form, and can infect villagers it kills (they will become normal zombies, not crawlers)
A zombie spawning has a 10% chance to spawn as a crawler.