Why play oppossum?

Interesting article on the weirdness of the phenomenon of animals "playing dead."

Excerpt:

The list of animals that play possum includes not only the Virginia opossum, of course, but also some 21 snake species and plenty of other creatures as different as bison on the prairies and brittle stars in the oceans.

Many of these animals freeze when a predator appears, and standard wisdom maintains that predators lose interest in prey that doesn't move. Yet some biologists now question that truism and are looking for a fuller explanation for the roles that feigned death might play in animal interactions.