In the early 70s, filmmaker Steven S. Wilson was working for the Navy in an isolated area near China Lake. One day, he was sitting on a rock, surrounded by sand, and an idea came to his mind: what would happen, he wondered, if something under the ground forbade him to get off that rock? He remarked in an interview with The Official UK Tremors: “one of my first jobs was working as a film editor for a naval film company that worked in the desert at a naval base in California. We used to hike around the gunnery ranges out there and I was always making notes for ideas for movies. So at one point, I was hiking on these big rounded boulders which were very much like the ones that we ended up shooting in the movie, and I made the note: ‘what if there was something under the ground, like a shark, and I couldn’t get off this rock?'”

Said note remained in Wilson’s file folder, until 1984 — when he (and his writing partner, Brent Maddock) found a chance to finally bring it to the screen. Having sold the script for Short Circuit, and having been hired by Steven Spielberg to collaborate on the scripts of Ghost Dad and Batteries not Included, Wilson and Maddock were allowed to propose a project of their own. Wilson recalled in an interview with Cinefex: “our agent, Nancy Roberts, sat us down and said, ‘okay, guys, now comes the fun part: for a brief time, anybody will listen to anything you have to say. What’s in your files?’ So Brent and I got together and we picked from each of our files ideas that we had jotted down, including my ‘monster in the ground’ concept, which at the time was called ‘Landshark’. Nancy loved it and we began working on a twenty-five page treatment.” Long time friend Ron Underwood — with no previous experience in creature features — was attached to direct the project, and also collaborated to the script.

According to Maddock, the film was initially shaped more like a comedy than the final product, mainly due to how the monsters were narratively treated. He recalled: “the project was much more comedic in its early stages, and we got to a point where — towards the end, a number of drafts in — we made the decision that we wanted the audience to take the monsters seriously; to feel that the monsters were a real threat. So we went back and we took out some of the humour. We didn’t want to go so far that we were poking fun at the idea of the monsters. We went about as close to it as we could get without losing the sense of real jeopardy.”

In an attempt to differ from usual monster films, the creatures’ origins were also deliberately left unknown. “There was a big debate about it early in the process, Wilson said in the Making of Tremors. “First of all, we didn’t care. Since I’m the one who comes out of science fiction films, I was saying, ‘there’s only four places they can come from: they’re either radioactive, or they’re a biological experiment, or they’re from outer space, or they’ve always been there. These are the only options you have.’ So I didn’t want to say it. In fact, I said ‘let’s say all of them at the same time.'” Underwood added: “it was more reality-based that [the characters] wouldn’t figure it out.”

Monster makers Alec Gillis and Tom Woodruff, Jr. were hired to bring the subterranean creatures to life. Tremors, in fact, marked the first creature effects work of Amalgamated Dynamics, which the duo had recently founded. Gillis and Woodruff came highly recommended by executive producer Gale Anne Hurd, having already collaborated with her during the production of The Terminator and Aliens. Wilson recalled: “Tom and Alec were excited about having a fairly big project land in their laps, but their company was so new that they did not have a facility set up yet. So we met at Marie Callander’s in Burbank to discuss the script and what we wanted the creatures to look like. The script had just a few lines of description. It said that the mouth opened like some kind of grotesque flower and there were horrible tentacles inside it and it had spines all over its body — and that was about it.” The spines were conceived to be the creature’s method of locomotion. Maddock explained: “it had these spikes on it that it moved along with. This was all based on what I knew about earthworms – which was not much, except that they have these stiff hairs on them and that the hairs point backwards and that’s how they move.”

Then — A HUGE MOUND OF EARTH RISES UP UNDER VAL AND EARL!! The cowboys tumble down its side, Val losing his rifle.  They roll over and stare dumbfounded at the mound.

VAL (cont’d)
(gasps)
There must be a million of them!!

The mound of earth turns toward them.  The ground splits open and out rises — a huge head!

EARL (awestruck)
Nope… just one.

The monster is a horrendous thirty-foot long eating machine! Its head is eyeless, utterly alien, covered with tough boney plates which close together to form a cork-screw point. The cowboys stumble back toward the fence in speechless terror.  The creature slides toward them, pushing through the earth like a whale through water.

Now it opens its mouth — but it’s like a grotesque flower, boney plates spreading open like petals, revealing a huge, slimy, fleshy, oozing orifice! And inside the mouth, a ghastly multi-tentacled tongue! These are the “snake things,” not snakes at all but actually the horrid hook-tentacles that can shoot out six feet to snag their prey!
-S.S. Wilson and Brent Maddock, Tremors early draft, 1988

Based on the simple descriptions provided by the script, Gillis and Woodruff began designing the monsters — which at the time had no precise label. In the script (and film), Walter Chang proposes the term Graboid, a name that would become official in the sequels. Gillis and Woodruff were inspired by a variety of real animals. “Whenever we’re designing a creature,” Woodruff said, “even if it’s some fantastic monster, we really like to go to research books of real animals — looking at forms and details like skin texture, coloring, even the way the animal moves — so it has a basis in reality. If there’s no reality, it’s all completely made up, completely fantastic — there’s a sort of unreal quality to it that’s hard to get over.  and were also aware that they should not imitate precedent creatures, such as the Sandworms from Dune. “What we did not want to do,” Gillis said, “was repeat what had been done in Dune. Because in Dune, the Sandworms were like earthworms, sort of more muscular, you know. They seemed to be kind of like a long muscular tube — rather than anything with a skeletal structure or armor plating.”

In fact, worms were not used as reference. “We actually did not look too much at worms because they are very boring,” Gillis said. “We used a ‘form follows function’ kind of thinking. We wanted something that looked like it could come from this planet — or could come from another planet — but it had to be functional and look like it was part of a desert environment. We started off by considering its mode of movement — whether it was a muscular movement or more like a locomotive that could barrel through the ground. For dramatic reasons, Ron liked the latter idea. With that in mind, we went with a heavy armored look rather than something slimy and soft and undulating. The outer surfaces combined the look of a crocodile skin with the leathery dry look of an elephant’s skin — cracked and wrinkled around its points of movement.” Dinosaurs and rhinoceroses were also used as reference. The ‘battering ram’ movement through the dirt (“like killer whales,” as described by Gillis) implied a mechanism that would enable the creatures to propel themselves through the ground; the spines, now distributed on the sides of the torso, became that expedient.

The head of the Graboids was a key element of the design, and one that went through a considerable number of iterations. Since the beginning, the special effects artists wanted to make it bony and armored — so that the creatures would be able to overcome most obstacles. “If a creature were to be swimming through sand or dirt,” Gillis said, “it would need a pointed, armored head, so that it could push that matter away, and then the rest of the body then would have some sort of muscular action.” The monsters also lacked eyes — another challenging aspect. Woodruff continues: “the script also specified that the creature not have eyes — which makes sense for something that lives underground, but it was a challenge for us — because eyes are such an important point for emotion and expression. Without that focus point you have to rely more heavily on the body movement. Since its entire head was just kind of a big bony shell, there was not much we could do to make it register any kind of feeling. Its only real feature was a mouth.”

Wilson and Maddock in fact wanted “an unusual mouth,” and Gillis and Woodruff provided one — trying to stray from usual design tropes. “We also got rid of the idea of sharp teeth,” Gillis said. “We based the look on the head of a snapping turtle, with side mandibles angled down that could act as scoops. It looked threatening and like it could cut you up, but there were not the standard pearly white fangs you normally see on a monster.” Woodruff also told io9.com: “from our earliest beginnings and influencing the design of the Graboid by studying elements of a snapping turtle, I’ve always believed that the audience needs something to anchor a creature to real life. I believe true, unfettered art can exist in a different template but as part of the story-telling of movie, I want the audience to believe our work. So if they see the silhouette shape of a snapping turtle or the heavy skin breakup of an elephant or rhino it helps turn the gears in the head to believing the whole package.”

The duo originally conceived the head of the creatures moving independently to the body — functioning like a turtle neck. The concept, however, proved controversial and was discarded. Gillis explained: “at one point we designed the head so that it could move in and out of the dirt independent of the body. We had big thick folds of skin — kind of like a turtle neck — to bridge the body and the head. But we found that nobody who saw it called it a turtle neck — immediately they began calling it a foreskin. So that idea was out. We were dealing with something that was phallic in shape, so we had to take the curse off of that as much as possible.”

Gillis added: “I did this sketch based on a snapping turtle. Snapping turtles can retract their heads into a mass of protective flesh. This sketch shows how that might look. I asked mega producer Gale Anne Hurd what she thought of my sketch. In her inimitable fashion she said ‘I showed it to the women in my office and we all agree that we aren’t making a movie about giant penises chasing people around the desert.’ I laughed. She didn’t.”

Another signature element of the Graboids is represented by their tentacles. The script refers to them as simple appendages with no particular features. As the creative process progressed, however, the tentacles’ role was expanded — to the point where they fundamentally became a red herring for the audience. Initially, they seem to be the antagonists themselves, and not part of them. Wilson explained: “somewhere along the line, we decided to convince the audience that the movie was about big snakes that lived underground. It occurred to us that it would not be immediately apparent that the tentacle torn off the truck early in the film was actually part of a larger creature, so we decided to try and keep that a bit of a surprise. Then Tom and Alec came up with the idea of giving the tentacles mouths — but without throats. Since the mouths are essentially grasping mechanisms, a throat was neither necessary nor appropriate.”

The design of the tentacles itself went through different iterations — some of which were more ornate and with “almost a flower motif.” Weapon-like versions were also explored. Gillis related: “my thought for the first version was like a medieval weapon. A mace with grappling hooks. The quadrosected ‘mouth’ beak would roll open revealing rows of leech-like teeth. [We then tried] a Swiss Army knife approach, again with the grappling hook mixed with multi directional bladed teeth. Considering that in the film the tentacle tongues of the worms had to be mistaken for creatures unto themselves, these designs felt overworked and perhaps gimmicky or too alien. In the end, it was Tom’s design of a naturalistic catfish-like head that won out. The grappling hooks stayed and were useful in killing poor old Walter Chang in his store.”

Gillis added: “we designed the tentacles with a sort of catfish look to them. The idea was that they could flatten down and look quite featureless — almost like tongues — until their mouths opened.” Some elements of the design were also inspired by snakes, and the bulk of the surface was based on slugs.

The final Graboid design was conceived to be a vertebrate as opposed to a boneless worm; several details were added — such as the sutures on the head of the creatures — to exemplify this element of their biology. Maddock and Wilson were extremely satisfied with the appearance of the monsters. “They just knocked us out of our chairs,” Wilson said. Once the subterranean monsters reached their final incarnation, the special effects team began constructing animatronics in various sizes — from full-scale creatures to miniatures. A quarter-scale maquette was first sculpted: “we knew we were going to do a quarter-scale creature — head to tail — for the miniature work, and originally we were planning to use that for a maquette,” Gillis said. “But we wound up not having as much time as we wanted, so the quarter-scale version only led the Others by about a week. Tom and I blocked out the sculpture and then Carl Sorensen and Dave Miller detailed it. We had the form done on the quarter-scale and pulled a mold and made a plaster duplicate off of the fgront end of it to serve as a model for the full-scale head. Mark Wilson, Howard Berger and Bob Kurtzman did a lot of the sculpting on the big one.”

Five full-size creatures were built in total: four head sections and a featureless dummy of the full creature, used in the scene where one of the Graboids, having recently died, is unearthed and analyzed by the protagonists. The eight-feet long head sections featured an internal structure composed of appropriately shaped aluminium bands; the skin was cast in foam latex — as opposed to the then commonly used polyurethane. Woodruff explained: “foam latex has a nice, compressed look to it; because the creature was so big, though, we had to build a custom oven — an eight-foot box — to be able to cook these things. Inside the foam latex we did pattern tracings of where the body was wrinkling on the outside; we did that so we could pad up the inside, but still leave divisions where the wrinkles were so that when the skin moved it would naturally fold along the same lines that were already sculpted into the creature.” The head, jaws and mandibles were instead cast in resistant fiberglass, which infused them with the desired plated appearence.

All the creatures were painted with primary grey and brown color schemes. The full-scale head sections were mechanized primarily by Craig Caton and Jeff Edwards. The mobile fiberglass parts were attached to a metal plate and connected to a large spring, which was in turn mounted on a backpack. Depending on the demands of a specific sequence, said backpack could be worn by a puppeteer, or be installed on on one of the rigs devised by physical effects supervisor Art Brewer, who also directed the construction of the shaking building sets for the film and other practical effects. Gillis explained the mechanisms: “the head movements were actuated by four rods that came out from the metal plate like a parallelogram. The rods went back to a T-bar; and whichever way you moved the T-bar, the plate in front would move as well.” The parallelogram mechanism was a modular device that could be “plugged” into the creature.

Halfway through the location shoot — Tremors was mainly shot in Lone Pine, California — ADI arrived on set; working in an abandoned railway station, the special effects artists shot the creatures in six weeks following the schedule. The Graboids needed constant repair, as — unlike many other films — they were shot in broad daylight. “We knew we were not going to have the benefit of shooting them in the dark,” Woodruff said, “with lots of goo coming off of them, and that had moved us to make them look as realistic as possible — more like an actual animal and less like a fantasy monster. When we got out to the desert, we found we were able to make use of all the dust, though, which took the curse off of it a little bit. Dust became a substitute for other things that we are used to using. It was actually refreshing to be able to exchange dust for slime.”

Nevertheless, saliva — thus slime — was actually needed for the mouth interior, as recalled by Gillis: “we had just come off of Aliens recently; we said to ourselves, ‘Aliens was a dark movie. Everything in it was wet and slimy. This seems to be more about broad daylight, hot, dust. Let’s stay away from the slime. Let’s just let them be a little drier and create their own character; that way it’s a little different than what you usually see’; and we didn’t slime up the mouth. It was glossy because of the coatings we put on it, but it was dry. We saw it in the dailies, and the editor remarked that it looked kind of like it was painted with nail polish. We didn’t fully understand that comment but understood what he was reacting to — which was the lack of wetness. So we started putting the slime on it and doing the webbing in the mouth.”

The creature effects team worked in close collaboration with Art Brewer. When one of the creature heads was filmed above the ground, the shot usually required operators in a 12-feet deep pit — dug by the physical effects crew — and external puppeteers.
Gillis elaborated: “in the pit, the creature was used as a big rod puppet — everything was connected in the back. We had cable controllers hooked up to the jaw and mandibles, and each could operate independently to get the snapping movement. The head itself was operated by using the T-bar at the end of the rods. It would lunge forward by means of a sliding rig that was anchored inside the pit. It took two guys holding the parallelogram, a third guy to help with the upward motion and then three more guys above ground operating the cables. The guys underground were handling the gross movement, while the articulation of the head was operated by three guys up top. The guys in the pit really had the worst of it. The pit was shored up with plywood, like a big box. The top had more plywood around the creature — as snug as possible — and then we would close them up and dress the whole area with sand and vermiculite. The operators had to wear respirators because the pit would fill completely up with dust. There was no light except the glow of a TV monitor that was supposed to help the puppeteering. In fact, however, the people inside could see nothing at all — especially since there were air tubes rigged up to blow dust all around. So they had to puppeteer the thing by feel alone. We were up on the ground giving them directions by two-way radio and they would just feel around in the dark and to the best they could. The operators were as blind as the creature was supposed to be — but they could not hear nearly as well.”

The sequences involving the Graboids bursting out of the ground were among the most complex effects stunts achieved for the film. For these scenes, the controller backpack was worn by a single puppeteer — Woodruff, usually — who was lowered into the ground through an elevator rig. “We built a 10-foot aluminium elevator,” Brewer said, “that was 60 inches in diameter. It was operated by means of pneumatic cylinders — the same kind used by NASA on the space shuttle doors. The cylinders are made in Houston and are very clever high-tech rams run by oxygen and nitrogen. We used them to power the Platform inside the elevator. The prototype Platform had been solid plywood, but we found that it created too much suction when it went up, so we switched over to a grated platform.” The rig was able to move at about 12 miles per hour — even when it carried the weight of the animatronic and the operator.

The rig was installed in an 11 feet deep hole with a 10 feet diameter and then covered with a 2-inch-thick piece of styrofoam painted dirt brown. The beak of the Graboid protruded from a pre-cut foam lid, and the entire system was camouflaged with vermiculite and sand. The elevator was operated from the surface and could rise, enabling the creature to erupt from the foam lid. Air hoses enhanced the effect by spewing additional dust. Brewer recalled: “we tested it at our shop before we went out on location and it worked perfectly; but then we got out to Lone Pine where it is all sand and pumice dust — and the wind was blowing constantly and all of that really sabotaged us. We finally found a silicone-based lubricant that the dust would not stick to and that pretty much solved the problem.” The elevator rig was completely self-contained and could be moved from place to place by a crane, to the point where the set-up time (including finishing touches on the creature) was cut down to about 45 minutes.

What actually infused life into the movements of the Graboid was the performer himself. Woodruff was positioned inside the elevator pit and lowered 10 feet into the ground, and had to wait for his cue; the experience was not particularly pleasant, as recalled by Woodruff himself: “it was one of the worst things I have done because the creature was so cumbersome and so difficult to move. I had a Watchman monitor inside the elevator to guide me, but it got to the point where I could not concentrate on that. All I could do was move the creature the way I felt it should be moving. It was quite an ordeal — I would strap the backpack on and climb into the elevator, put on goggles and radio gear and a respirator, and then they would drop the elevator down. Because of all the dressing they had to do around the area after the elevator was lowered, I would be down there for about 25 minutes before they were ready for a take. It was a very isolated feeling, even though there was air pumped in and it was very safe. One advantage to it was that it was the coolest spot in the desert. When they were ready to go, I would get into a crouching position and as soon as the elevator went up, I would stand to give it a little extra burst up through the styrofoam piece. Even so, it seemed to move at an agonizingly slow rate most of the time. The sound effects helped and they also minimized it in editing by cutting the shot down so that the creature comes out three feet before they cut instead of eight feet. But the rig moved pretty well. If it had moved any faster I probably would have had the thing crashing around me.” A second elevator rig was built for sequences where characters or objects are dragged in the ground.

Out of location ground, the Graboid was attached to a different rig — described as a “rolling dolly with an arm”. Brewer explained: “the creature was mounted from a parallelogram and hung from a custom-made crane so that it would stay level as it lunged forward. The rig was all steel, and with the creature in place it weighed about 900 pounds — we had to use 120 pounds of weight to counterweigh it.” The dolly rig was used on location — but was employed most prominently for the interior sequences on stage at the Valencia Studios outside Los Angeles. The first scene was the Graboid bursting through the market floor. Brewer recalled: “for the store scene, we put the dolly on a track and then rolled it forward and raised the creature up as it smashed through the floor — which was made of several layers of balsa wood so the creature could break it apart easily. The rig was manually operated by six people — everyone pushing and moving levers and cables. Two of the guys were operating the creature and they ended up actually riding the dolly.” A prosthetic broken leg provided the effect of the violent dragging, whereas the actor could sit in a seat rigged inside the creature’s mouth. The other scene involved a Graboid ramming through the wall of Burt Gummer’s basement. A similar method was employed — with the addition of a section with dirt and sand that the creature burst through — allowing the visual detail of sand dripping from its head.

The only full creature built for the crew, measuring over 30 feet from head to tail, was the featureless dummy of the dead Graboid that had collided with a concrete culvert, inadvertedly killing itself in the process. “We had built the basic frame for it in LA, and then we shipped it up to Lone Pine in sections. Whenever we got a chance, we would cast up skin pieces and glue them down and paint them. We built the entire thing from head to tail, but you do not actually see it all in the film. The set department had built a fake canal wall and then dug a channel to set our creature into. We had one of the heads in there — attached the full-length body — for the shot of Earl and Rhonda prying the cement off and the creature plopping out. Tom and I were inside pushing the thing out, and there were two other guys pushing out blood and slime. For the cracked skull on top we put slushed liquid polyfoam into the head mold and then sliced it up and offset it and glued it down like a giant worm appliance.”

Gillis also recalled the success of the scene, also determined by the amount of slime used in it. “By the time we got to the point where the dead creature — rammed into the retaining wall — they break it away and the head rolls out, there’s a POV shot where the camera is moving and there’s all this dripping slime. We really went overboard with the wetness there. We saw it at a test screening with a bunch of guys — heavy metal guys, with Metallica T-Shirts — guys that would really eat that up. When they saw all that dripping slime, the roof went off the theater — everybody was cheering. we looked at each other and said, ‘slime. Never underestimate the value of slime’.” The slime was, as usual, achieved with KY jelly.

All the life-size creatures could be fitted with the corresponding tentacles, whose movements were inspired by elephant trunks and octopus tentacles. Gillis and Woodruff, supported by crew members Mark Rappaport and Mecki Heussen, built several versions of the tentacles to work in cooperation with the full-sized Graboid heads — as well as insert puppets. The duo were already familiar with the creation of monster tentacles; Gillis recalled: “the tentacles on Tremors are the third generation of tentacles that Tom and I have worked on. We did tentacles on Invaders from Mars and Leviathan, so we were able to build on our past mistakes and rectify them. We made three 10-foot-long tentacles that were cable-operated — also a four-foot [tentacle] head section with articulated barbs on the head and chin that would stand up to give it more character in close-up. The spine of the tentacles was braided hydraulic hosing — which flexes any way you want, but does not twist. A lot of our previous efforts had ball joints and other things that would twist on themselves causing loss of control.” The internal structure also employed discs of delrin — a machinable lightweight plastic — that were bolted to the hydraulic hosing “to create a series of ribs.” Cables of bulkheads installed inside the model allowed for several points of articulation.

The jaw mechanism was anchored by a vacuformed understructure. Woodruff commented: “rather than having a single hinge point, we made two hinges to give it a compound movement and help widen the mouth out. It was a double-jointed jaw that hinged not only at the back but also about halfway up the thing. We liked the way it enabled the mouth to open really wide. For shots of the tentacles darting out, we used reverse photography. We started with the tentacles out of the mouth and we would slime them up and put them in a good position. Then we would go wild with them when we pulled them in. A large part of the challenge was just moving these things. The tentacles were not lightweight — especially with all the control levers. Only our strongest guys got to go on set with us. Normally we did not do too much operating of the head for those shots — the focus was on the tentacles coming out, so it was not as critical.”

Maddock also suggested the use of a hand puppet, a device that unexpectedly proved very useful during shooting. “He said, ‘what about a hand puppet?'” Gillis said. “‘You know; don’t you think we should have a hand puppet?’ We sort of said, ‘okay, we’ll have a hand puppet.’ We used that hand puppet more than we ever expected!” Woodruff added: “the hand puppet was used for close-up shots — like where the tentacle is snapping at the truck. Any of the finer movements like grabbing or snapping was done with the hand puppet. It was better for those kinds of things than the cable-operated ones because it was more maneuverable.” ADI also built nine stunt tentacles, devoid of any mechanical features. Additional gore for other scenes, such as when the third creature is killed, was achieved with latex patches and pantyhoses, both filled with orange methocel to simulate the blood. For the scenes where the Graboid intestines and other entrails are shot towards the characters, air cannons were used to shoot them.

By the time principal photography had wrapped in Lone Pine, miniature effects Veterans Robert and Dennis Skotak — in partnership with supervising producer Elaine Edford in 4-Ward production — were hired to shoot the miniatures. The Skotak brothers had already worked with Gale Anne Hurd on Aliens. “We were very impressed with the way the Skotaks approached their work,” Underwood said. “They are true artisans. We had gone into the project knowing that we needed some miniature work, but initially we were leaning much more toward full-scale. By the time we were through, we had a lot more miniatures than we had anticipated. Full-scale — no matter how well it is realized — is just really difficult to control.”

Miniatures, in fact, were used for actions and movements that the full-size creatures could not perform — or could achieve with certain restrictions. The miniatures allowed for more creative liberty in the sequences for which they were employed; in fact, the miniature work was so exceptional that the final film employed far more than originally intended, creating a whole second part of miniature shooting after the initial one.

ADI built five 1:4th scale Graboid puppets for the Skotaks’ miniature sequences. The first to be built was an animatronic version, with fully articulated head and neck mechanisms. The miniature puppet required different mechanical systems when compared to the full-size Graboids — since the mechanization would extend to the whole first half of the creature. “The head mechanics were similar in design,” Woodruff said, “but the body mechanics were based on the same principle as the cable-operated tentacles. We sectioned off the body core into disks — leaving spaces in between — and then fed cables through and out the back. If necessary, we could reroute the cables and have them run down and out the bottom.”

The tail section of the miniature Graboid was made of soft polyfoam; a departure from standard procedures, which involved fiberglass understructures. “It was something that Alec and I wanted to try,” Woodruff said. “We wanted the creature to sort of squish down under its own weight to give it more mass and bulk.” The head could be used independently, but the tail section could be attached if the shot required it. Simpler versions of the tentacles were built for the miniature Graboid. “they still had to have some movement to them,” Woodruff continues. “Very little of them is seen in the film. There was a feeling that there was a difference in movement between the miniature and the full-sized tentacles.”

The 1:4th scale Graboid animatronic was puppeteered by six to eight crewmembers. Gillis recalled: “there would be two people operating the tentacles, and then another person providing the gross body movements. Generally the creature was mounted on a pole that stuck up through the miniature set and the operator would be at the other end of the pole. We would have one guy operating the skull, one guy operating the mandibles and then one operator for each of the three body sections. Each operator had what amounted to a big joystick to control left-right and up-down movement on any given body section.”

The miniature animatronic was most prominently seen when the film first reveals the appearance of a full Graboid, bursting from the ground. The creature was filmed in a forced-perspective miniature landscape, built by the Skotak brothers, with a matte painting created by Rick Rische. Robert Skotak recalled: “physical effects had done the initial ground-breaking shot on location, then ours picked up with a POV after Earl and Val have backed away. The ground is just starting to crack — then there is a separate shot of the creature breaking through with dirt blowing up around it. That was our quarter-scale shot. The breakthrough was very straightforward — just a matter of actuating the puppet to break through a thin crust. We had fans outside to create dust blowing by and we had compressors below to kick a lot of dirt up into the air — whatever we could do to make the creatures look explosive. Steve Brien worked out most of the gags with us — and there would usually be several grips involved. Sometimes the creature was pushed out and sometimes it was levered up.”

To achieve the gun shots on the Graboid, pre-cut holes in the creature were covered with patches of skin and then filled with air lines. A BB gun was then used to create hits on the ground and the monster. For the shots of the Graboid traveling underground, a slot was cut into the table and covered with a foam rubber membrane. Thin foam-core plates were glued to said membrane, to simulate surface dirt. A pipe was moved through the underside of the rubber to achieve the effect of the ground heaving and cracking and settle back at the passage of the Graboid — which was maneuvered from below. Fuller’s earth, microballoons and miniature roots were added to enhance the effect.

As production progressed, the special effects crew found that the miniature animatronic could easily be replaced by simpler models — hand puppets. “Originally we expected that [the 1:4th scale animatronic] would do all of the quarter-scale work,” Gillis said. “But once we got into it, we realized that we needed something easier to handle — which is when we began making different hand puppets. We needed one to crash up into the ceiling in Burt and Heather’s basement — just a hand puppet with the mouth closed. Another one had an articulated head that was used for a lot of the stuff. We just built a variety of puppets that we could pick and choose from depending on what was needed.” Shots of the creatures heading down to the ground and other key sequences were achieved with the hand puppets.

Crucial to the miniature shooting was not only the necessity to match the miniature footage with the principal live-action footage — but also the fact the small-scale creatures had to be shot at more than 24 frames per second, in order to infuse them with a sense of actual mass. In this field the hand puppets also proved to be more practical than the animatronic. “Because the miniatures were shot overcranked,” Woodruff said, “we had to do our puppet movements twice as fast. We could get more specific movements with the fully-articulated puppet, but with the overcranking it got to the point where the movement was very random anyway. With a hand puppet, we could produce very hard, fast movements which were better suited for the way it was shot. The hand puppets had a grip on the inside that the operator could grab onto to steer the creature around. One of the hand puppets was articulated — the head could turn from side to side and it also had cable-operated jaws that opened and closed.”

The basement fight was the sequence where the miniature Graboids were featured most prominently — alternated with the full-size creatures.  “It was a similar idea to what Jim Cameron did on Aliens,” Robert Skotak recalled, “building the Queen and the power-loader in quarter-scale to get the big punches and rolls that would be impossible to do in full-size.” The Skotak brothers built a quarter-scale basement miniature –four feet deep, six feet wide, two feet tall — complete with individually-painted floor and ceiling tiles. The Skotak brothers “suggested things we could do that would have been difficult for [ADI] to do in full-size,” Robert Skotak said. “We did shots where the creature rears up through the ceiling and knocks some tiles off. We also did a shot where it hits the door and knocks it down. Finally, we did its death scene where it falls and thrashes about. Much of the basement sequence was done in miniatures.”

A prime concern was establishing a bond between the principal footage and the miniature sequences. Robert Skotak said: “we discussed with Ron and Steve the lack of shots with the creature and the people together. There was an over-the-shoulder shot where Michael Gross shoots the elephant gun at it, but that was one of the few. So we came up with the suggestion of doing a whip-pan which looks as if it is one continuous shot with both the character and the actor together. The idea was that Michael Gross would drop a gun and we would do a shot of him desperately grabbing for it on the ground. Then we would do a whip-pan off the set and do a corresponding whip-pan on the miniature set of the creature lunging forward. A simple cut in mid-pan would effectively join the two.”

The live-action shot was done with crewmember Ray Greer playing Burt for that specific shot, plus details like falling cartridges and shadows. “It looks flawless and like it was all part of it,” Robert Skotak said. The scene again featured bullets hitting the Graboid. Robert Skotak estabilished cuts in the backside of the creature. “Then the pyro guy would come along to lay his squibs in and we would replace the plugs and color over them,” Woodruff said, “and add lots of dust so that when the impact happened there would be a puff of dirt. We had three phases of squibs all wired at once. The first was supposed to look like small arms fire. Those would all be blown out first. Next would come larger-caliber rifle hits and machine gun fire. Finally the mouth and back of the head were squibbed for really big elephant gun hits. So the thing was just riddled with squibs.”

The basement scene was technically the last intended miniature shoot; when Tremors was shown in its rough workprint for the studio, Universal executives were enthusiastic about the creature effects — to the point where they authorized an additional budget to increase the creature effects shots. “In the rough cut, the creature had been shown only obliquely in many instances,” Robert Skotak recalled, “its presence suggested by moving clouds of dust and rumblings and windows shattering. Now the idea was to go in and add another 16 or 18 shots to flesh it out. This time we decided to shoot indoors because it was now late into August and the days were getting too short to shoot outside.” Unlike the ‘phase one’ miniatures, the ‘phase two’ ones would be shot in artificial light. despite concerns, the Skotak brothers achieved perfect matches with the live-action footage. Among the sequences was the shot where the Graboid is seen circling the boulder on which Rhonda, Val, and Earl are confined. “Ron felt that he needed to establish at least a couple of shots where you saw a shape come out of the sand and then go back down again,” Robert Skotak said. “He felt he needed that to sell the idea — a down-angle of it coming out and then the hole filling up after itself.” A mixture of fuller’s earth and colored microballoons was used to simulate the sand and the environment.

A featureless 1:8th scale puppet was built by ADI and maneuvered from below through crescent-shaped slots cut into the set. “On both sides of the crescent there were chambers,” Robert Skotak said, “like drawers — full of microballoons and fuller’s earth, and as the creature rose up the hill in its path, someone on either side would be feeding in new soil mixture to bring the level back up to normal as it dove down at the far end.” Air lines eased the creature’s traveling. An additional shot of the Graboid rearing its head to snatch the shovel was achieved with the hand puppet.

“The whole second batch of shots were here and there shots, rather than whole sequences,” Skotak continues. “They were spread throughout the film — little things that revealed the creature in action. We did a couple of burst-ups against the sky — just shots of the creature going up and then back down. There was a scene in a lot between the general store and the trailer where the creature breaks out and kicks a bunch of timber in the air. Also superfast traveling shots across the yard in pursuit. We did a shot of the creature jamming the underside of the trailer, as well as one where it is shaking the house underneath. There was a scene where the characters are pulling the bomb across the yard and the creature comes up and grabs the bomb, so we had to make a miniature bomb with a smoking fuse. We also did a POV from the rooftop where the creature is heading towards the survivalists’ house and it comes up out of the ground and keeps on going across the landscape. That one was also done in eighth scale, which made it difficult because we found it was harder to get the nuances of the set dressing at that scale. We put heating elements under the camera on that shot so that we could get a telephoto effect — a mirage-like shimmer.”

A dual scale shot used both the quarter-scale puppet and the eighth scale puppet, and was achieved with forced perspective — when the camera passes from the former to the latter model. Fuller’s earth was blown diagonally across the set to help achieve the effect. Additional Point-of-view shots were filmed, showing the Graboids’ travel through the ground: dirt and lightweight rock props were shoved into a vertically-placed camera.

At the end of the film, the last surviving Graboid is lured through the side of a cliff when Valentine McKee throws a bomb right behind it — thus making it accelerate for the intense sound. The monster breaks through the cliff wall and meets a gruesome demise, falling into the canyon floor. A highly realistic 1:4th scale miniature cliff was built for the sequence, which was part of the initial portion of miniature shooting. “Steven and Brent and Ron were very much into desert geology and they really wanted everything to make sense from a geological standpoint,” Robert Skotak said.  To make the Graboid break through, a hole was cut in the side of the model cliff — and a ramp was positioned behind it. The opening was then covered with wet paper toweling and portions of broken plaster and dirt. The creature was then placed on a cart that would be driven up the ramp and rammed through the covering.

The first breakthrough was achieved with the miniature Graboid animatronic, which was also used for the last close-up of the creature’s head as it frantically screams to its death. The shots of the falling creature employed a full featureless dummy. For the sequence where the Graboid finally splatters on the canyon floor, a gelatin creature was first considered — but discarded for time constraints. Woodruff explained the process: “we made a polyurethane skin that was prescored and draped around a core section made of rope. Inside of that, we put condoms filled with orange methocel creature blood. We had thought we were playing it safe by making the creature strong enough to sustain three takes — but the one that ended up on screen was take number nine. After each take, we would open the creature and clean it up while two of our guys filled a new batch of condoms and tied them off. Then we would put them inside the body and superglue the skin shut. Invariably, one would break while we were tying them and worm blood would get all over the thing. Since we had been prepared to do only three takes, we ran out of condoms quickly. So we sent Mitch Coughlin — the youngest guy in the crew — across the street to the pharmacy. Three times in one day we sent him to get more condoms — he was getting some real respect from the people over there.”

Once filled and ready, the ‘splattering’ Graboid was hoisted by its tail over the set and released on cue to the canyon floor. Dennis Skotak recalled the complexity of the sequence: “much of the difficulty in the drop was fighting gravity. We had to hoist up all this weight and try to keep the condoms from breaking — and all of this before we lost our sunlight! The drop was actually only about 12 feet to the point of contact — the creature was so heavy, it did not need to drop far. Getting it to drop exactly where and how we wanted was the biggest problem. We had designed the rock so the creature head would kick back and the body would flatten out in a certain way — but, of course, it never would hit right. Either it would go too far to the left or too far to the right, so we had to do it over and over again and the turnaround time was hours and hours. One of the difficulties we had was that all of the blood and guts splattered out and sometimes hit the two cameras we were shooting with. We would have had a good shot going and then a big wad of stuff would strike the lens and drip down into the frame.”

The fall was filmed at 72 frames per second. Wilson was extremely satisfied with the miniature effects work, saying that “there are many miniature shots that you would never know are miniatures. The Skotak stuff is just that good. Full-scale creature and miniature creature are intercut throughout the basement sequence and we literally just picked whichever one was doing the best action. We did not have to concern ourselves with whether something looked like a miniature — after a while we forgot all about it. We were just flabbergasted by their work.” Underwoord ultimately commented on the effects work of ADI and the Skotaks for Tremors, saying that “with the greater complexity of feature filmmaking, you thank your lucky stars for all of the incredibly talented people who come together to help make your ideas possible.”

For more images of the Graboids, visit the Monster Gallery.

Next: Tremors 2: Aftershocks