It was the practice in the 1950s (at studios like AIP and Allied Artists) to devise a double-feature program by coming up with the genre and the movie titles and to pre-sell bookings of that package to drive-ins and hardtop theaters. Once the "territories" were covered, the titles, along with a predetermined budget, could be handed over to a producer/ director like Roger Corman for the actual production. The titles and ad campaigns were geared for exploitation, of course, and Attack of the Crab Monsters proved to be one of the most famous titles of the era.

For the screenplay, Corman called on his friend and frequent collaborator, Charles B. Griffith. Griffith was interviewed at length for Corman's autobiography (How I Made a Hundred Movies in Hollywood and Never Lost a Dime by Roger Corman with Jim Jerome) and said "When Roger first told me he wanted this crab picture, he said, 'I want suspense or action in every single scene. Audiences must feel something could happen at any time.' So I put suspense and action in every scene. Usually, I'd do a draft in two, three weeks, with very little discussion with Roger. Then he'd take my first draft and say, 'Let's tighten it up a little.' So I'd make a few changes and type it over with wider margins. That gave me a lower page count and Roger was happy."

Attack of the Crab Monsters was filmed partially at Leo Carrillo State Beach, a favorite location of Roger Corman's. The California beachfront can also be seen in such Corman-produced pictures as Monster from the Ocean Floor (1954), The Saga of the Viking Women and Their Voyage to the Waters of the Great Sea Serpent (1957), The Terror (1963), and Voyage to the Prehistoric Planet (1965). Corman called the location "picturesque" because "the rocks come down right into the ocean."

Other filming locations included the famous and oft-used Bronson Caverns (for the cave interiors), and a large water tank at a nearby theme park, Marineland of the Pacific, for underwater scenes. Charles B. Griffith served triple-duty on the picture. He not only wrote the screenplay and played a bit part in the film, he also directed the underwater sequences. Griffith said, "I had recently seen Jacques Cousteau's first picture and loved it. I went to Roger and said, 'Hey, I'll direct the underwater stuff for a hundred dollars.' He grabbed the bargain. It didn't occur to Roger that I didn't know anything about diving or directing. Weeks later – I think he went to Hawaii and shot two other pictures - he called and said the actors were going to my place to learn how to dive. Not from me they weren't." Another actor in Corman's stock company, Jonathon Haze, was an experienced diver and volunteered to donate the diving equipment to the crew, as well as instruct the actors. Griffith arranged to have Haze instruct him prior to the others.

Griffith encountered his biggest troubles when it came time to film the crab prop underwater: "The shoot in Marineland, the first time I directed, was horrendous and chaotic. We used a papier mache crab on an aluminum frame, with Styrofoam stuffing inside. The only problem was the crab wouldn't sink. It floated. As Roger watched, we had to keep loading rocks, cast-iron weights, and people on this crab just to get it to stay underwater."

The crab prop was also difficult to maneuver on land as well. As Beach Dickerson relates in the Corman autobiography, "I got the part of a scientist who comes ashore and the crab eats me. I also played the crab along with Ed Nelson. You never played just one role in a Roger movie. They brought this big crab out there and I asked, 'How's it going to work?' And no one knew how this crab was supposed to work. It was made of papier mache. We got some piano wire to help move the claws. I said, 'Well, someone's got to get inside the f**king thing and lift it up and you need two people in there.' Ed and I figured out that if we got inside, bumped asses, and locked arms at the elbows, I could pull him north, he could pull me south, I could pull him east, he could pull me west."

Ed Nelson was interviewed by Tom Weaver (in Attack of the Monster Movie Makers: Interviews with 20 Genre Giants), and his memory of the crab prop proved to be the most reliable; he said that "the crab was made by Dice, Inc., and it was a heavy piece. It was fiberglass, and I would say it weighed like a hundred forty pounds, something like that. What they did was, they had piano wires on the end of every elbow of the crab, and on a long stick way up in the air they had these wires connected. And people out of the frame would be holding up these sticks. They would alternate picking them up and lowering them, so the legs would move. That worked fine. Inside the crab was a hole no bigger than maybe four feet, and I would get in there. They would put pads on my shoulders and I would bend over and pick up the body of the crab and walk along, in a squat. In my hands I held two wires which worked the eyelids, and I could pull on those and the eyes would open and close. So I had that double job. Roger would set the camera up so that there would be rocks in front of the lens, down low, so that you wouldn't see my feet. And it worked pretty good."

Ed Nelson recalled one blooper from the film: "There is one place where you can see my feet [under the crab]... The girl scientist, Pamela Duncan... she is in a scientific lab, and she shows one of the professors stills of the Crab Monster that she has taken and she notices that the crab is pregnant. You cut to one insert of the photographs of the crab, and in that insert you can see my feet hangin' out the bottom. I saw it on the big screen in downtown L.A., and I said [loudly], 'They're my feet!'"

SOURCES:
How I Made a Hundred Movies in Hollywood and Never Lost a Dime by Roger Corman with Jim Jerome

The Films of Roger Corman by Alan Frank

The Films of Roger Corman: Brilliance on a Budget by Ed Naha

Return of the B Science Fiction and Horror Heroes by Tom Weaver

Attack of the Monster Movie makers: Interviews with 20 Genre Giants by Tom Weaver

by John M. Miller