I thought this video would teach me how to pull a screenshot from a DVD

Fun, but I have quibbles.

1. It can't be both a reptile and an invertebrate. Should decide whether it is a legless lizard or highly advanced annelid.

2. It cannot have "subspecies" developing inside it. What it gives birth to is by definition the same species. What this appears to be is a case of alternation of generations (something seen in jellyfish and Alien), in which body forms switch back and forth with each generation.

So it's a tremor right?

I'm disappointed they didn't get into the other stages of a Graboid's lifecycle. They barely mentioned the Shriekers that exist to spread and multiply, then the Assblasters that exist to carry eggs to far off destinations.

No mention of their arch-nemisis Burt?!