A dirt alligator lives in the earth, not the water. They can swim through the earth itself! Which is pretty scary.
You can think of this word as ground too, because that's kind of what earth is made of.
The only way to keep this dirt alligator from dragging you under the earth and eating you is to feed it cheese (ち). That way it won't lead you to a horrific death under the earth by dragging you under and spinning you around until you eat dirt (literally).