The team was also aware of eventual criticism, claiming that “the core of the Tremors fan base and the original creators were so addicted to the original look of the movies and somehow nobody could imagine a full CG Tremors.” Previously, the digital Graboids featured in Tremors 3 had been criticized by enthusiasts of the series. Additionally, the Cinemotion team commented on the digital Shriekers in the second film, saying that “they looked so terrible that nobody wanted to take on that challenge again.” As a result, the digital effects artists committed for high quality work. “This was a huge responsibility for us, and the only way to be true to the fans was to deliver CG creatures of exceptional quality.”

As the Graboids in the film are a different strain, the story shifted certain aspects of the creature concept: the Shrieker stage of the life cycle is entirely skipped. For that same reason, the Cinemotion team was allowed wide creative liberty in the design and animation of the new Graboids and Assblasters. “A focal point of our redesign was the fact that those creatures are in South Africa,” Trichkov said, “a completely different branch of Graboids. Like many other animals, the African Graboids were supposed to be older and more evolved, faster and more agile.”

The new concept was inspired by African termites. “During the preproduction I visited a paleontological institute in Johannesburg, and had the chance to speak with Adam Yates, one of the most respected paleontologists in the world,” Trichkov said. “He told me about a very interesting termite that still lives in the areas and is able to burrow through rock. First it spits formic acid, melting the rock, and then using his magnesium mandibles to dig through it. Fascinated by the fact that there are actually creatures like the Graboids, we just took the creative license to make them about 7000 times bigger and able to dig 2000 times faster [sic].”

Based on that same termite, the new Graboid’s beak became obsidian black; its anatomy was also changed, with tendons, more mandibles, and an overall different beak shape. In order to make the Graboid a faster digger, the creature designers modified the anatomy of its body to a corkscrew shape. “Magnesium is black, so we changed the Graboid’s mandibles to black. We changed their bodies to a corkscrew shape, because that seemed like the only way this creature could travel underground without displacing huge volumes of dirt.”

According to Trichkov, “the viewer always needs to see eyes in a creature, otherwise it is too anonymous and not as terrifying.” However, since the inclusion of eyes would have been too big of a departure from the original concept, the team settled the issue by putting eye substitutes in the creature’s head — in the form of shock-sensing organs. “We put shock-sensing organs on top of its head, and two small dents in the place of eyes since a subterranean creature does not need to see.”

The Graboid’s tongues — labeled by the crew as ‘grabbers’ — can detach from the main creature and move separately from it. “The Grabbers in this movie have a unique feature – they are able to travel separately from the mother Graboid. This called for a slight redesign so they have enough features to be able to dig through the ground and slide on top of the ground. The production team have built physical model Grabbers to be used in many of the shots, but in the final edit all the shots in the movie used a CG version of the Grabber.”

When it came to the new Assblaster, Trichkov was not too fond of the original iteration. “To be honest, I hated the original Assblaster design and I thought that it could be greatly improved,” he said. “My thought was to make it more vicious, more agile and to make it look different from everything else. Here, as always, the devil was in the details: the turbine at the end of its body holding flammable gas; the two curved bones that ignite the flames from that same turbine; the burned-out scales left from hundreds of fire blasts; the small weak wings used for gliding; the way the wings fold invisibly into the body; and of course, the grotesque mouth.” Unlike the previous Blasters, the new creature had literal wings, as opposed to gliding sails.

Trichkov also wanted to make the Assblaster look more related to the Graboid, as the Shrieker stage was missing. “One of my aims was to bring the Assblaster much closer in appearance to the Graboids, because they are directly related. Graboids are hatched from Assblaster’s eggs and they should look more like each other than they had previously.” One last touch to the digital model was a charcoal material covering on the back that progressively faded out towards the head, in order to suggest the long term effect of the tail combustions.

With the exception of some gore effects and sparse practical shots of the grabbers, the creatures were entirely digital. Physical reference for the grabbers was used on set, only to be replaced in post-production. Visual effects artist Pavel Pehlivanov devised an auto-rigging system for the creatures. “It was clear that there would be a lot of back and forth and many more iterations in the process compared to some of the other projects we have done,” he said. “The only way to do that was to automate the rigging process as much as possible. This was a great opportunity for me to finish the auto-rigging system I had been developing for quite some time. It allowed us to rebuild the rigs in a fraction of the time, after every design or model change.”

When it came to actual animation, the digital effects team researched the body language of the original creatures, but ultimately created whole new animation systems for the new Graboids and Assblasters. “Despite the fact that there is no shot in the film where the Graboid is seen underground, it felt right for the whole animation team to explore different options of how the new corkscrew shape would work. That helped us create a lifelike appearance for the ground breaching and in-air movements of the creature. We extensively researched the way the Graboids moved in the original series, but because of the design changes and more vicious mentality, we couldn’t re-use most of what we found there.”

Danny, animation supervisor, concluded: “at the end, I think we were able to breathe life into a fresh concept, and I really hope that the hardcore fans will embrace the new, more modern design.”

For more pictures of the African Graboids and Assblasters, visit the Monster Gallery.