5. Crab Crawl
Babies who move backward or sideways when they crawl are said to be doing a crab crawl. This is sometimes a phase until your baby learns to move forward or simply he has his own way of doing things.
6. Rolling Crawl
Babies who get from one place to another by rolling rather than using arms and legs seem to have a need for speed. They can certainly move very fast this way, but fine navigation and turning radius are sacrificed for sheer velocity.