This skin-crawling classic turns 25 today. Here are a few things you might not have known about the first (and last) “thrill-omedy.”

1. IT WAS A LONG-TIME SPIELBERG COLLABORATOR’S DIRECTORIAL DEBUT.

Frank Marshall had produced a number of films for Steven Spielberg’s Amblin Entertainment, including The Goonies, Poltergeist, Gremlins, Empire of the Sun, and The Color Purple (among many others). He had directed second unit photography and some short films—including making-of documentaries for the Indiana Jones movies, which he also produced—but Arachnophobia marked Marshall's feature film directorial debut. “As a producer for 20 years, I know how hard directing is, and I didn't want to do anything I'd had no experience with,” he told The New York Times. “Disney's Jeff Katzenberg sent me the script, and I felt it was something I could do. I didn't want to get into a serious dramatic piece that might stretch me beyond my capabilities.” 

2. THE ORIGINAL SCRIPT WAS MORE HORROR, LESS COMEDY.

When Jeff Daniels came on board to play Dr. Ross Jennings, Arachnophobia was a serious horror movie—one that Daniels told Philadelphia’s Daily News was pretty formulaic. "You could tell that the lines were kind of written by computer," he said. He and Marshall were hoping for a black comedy with a more ironic tone, so the script went through several revisions, and the filmmakers studied Hitchcock films and Jaws to get the tone right. One key change: Daniels’s character was given a fear of spiders.

The result, Daniels told the Orlando Sentinel, was a one-of-a-kind movie. “It's not really horror,” he said. “We don't have chainsaws going through necks and blood spurting. It's scary, but this is not The Attack of the Killer Spiders. We approached it as a comedy with a couple of thrills. We knew we had the thrills in there, so we worked hard to make sure the movie had a sense of humor about itself.” The humor, he said, “kind of relaxes the audience, so that we can come in and get them again.”

“We wanted it to be scary, but not too terrifying,” Marshall told Entertainment Weekly. “We didn’t want it to be a typical horror movie—The Spider That Ate Cleveland—so we used a lot of comedy. We tried to make it like a roller-coaster ride for the audience. It’s frightening, but in a fun way.”

3. THE PRODUCTION SHOT IN A PART OF VENEZUELA WHERE NO MOVIE PRODUCTION HAD FILMED BEFORE.

For the opening sequence, which takes place in South America—and where a photographer is bitten by a deadly spider that then hitches a ride back to the States in his coffin—the crew headed to the Tepuis of Venezuela's Canaima National Park. No movie had filmed there before, and getting to it was hard work: They set up a base camp in a location that was meant for one-night stays, and stayed for four weeks, flying in all of the necessary equipment and food. They used five helicopters to fly up to the mountains every day.

“The Tepuis rise out of the rainforest almost 10,000 feet,” Marshall said in a featurette created for the movie. “Because they’re so high up, they’re right in the cloud bank, so the weather is [always] changing. Some days I would just get one take—not one scene, one take—and it would be an hour before the sun came out again. There was one day we were trapped the whole day; we had actually built the survival camp, and 15 minutes before we were going to be stuck all night, the clouds opened up.” Abandoning their equipment, the cast and crew “jumped on the helicopter and got out just in time,” Marshall said. “It was kind of exciting.”

4. ONE SPIDER USED ON THE PRODUCTION WAS NAMED FOR A HOLLYWOOD DIRECTOR.

The production required two species of spider: The first—the arachnid that hitches a ride from South America to California—needed to measure about one foot across. The filmmakers found their star in a bird-eating tarantula native to the Amazon; there was only one such spider in the U.S. Marshall named the spider Big Bob after director Robert Zemeckis. 

5. THE SPIDER HAD TO BE MADE SCARIER FOR THE MOVIE.

As terrifying as Big Bob was, he still wasn't scary enough for Arachnophobia. So the production painted purple stripes on his back and added a prosthetic abdomen “to give him greater bulk,” according to Entertainment Weekly

6. TO CAST THE SMALLER SPIDERS, THE PRODUCTION PUT THEM THROUGH A “SPIDER OLYMPICS.”

In the movie, Big Bob arrives in California and promptly mates with a house spider, creating super deadly offspring. To find the right arachnids for the job, Marshall and his team evaluated a number of species—including wolf spiders, tarantulas, and huntsman spiders—by putting them through a “spider olympics,” running each species through 10 tests, including speed (the faster the spider, the scarier it is), climbing ability, and reaction to heat and cold. 

The “gold medalist,” according to Marshall, was the three-inch-wide Delena spider, a harmless but sinister-looking huntsman native to Australia that was introduced to New Zealand in the 1920s. Marshall joked that “we got them all little passports,” which was sort of true: The production did have to jump through hoops to bring 300 of the spiders to the U.S. for filming (and that was just the initial shipment; supplies were replenished every two weeks).  

7. JOHN GOODMAN WASN’T FREAKED OUT BY THE SPIDERS. 

Though Daniels claimed that he was fine with small spiders, he acknowledged that “anyone in his right mind” would have issues with spiders as huge as Big Bob. But John Goodman, who played exterminator Delbert McClintock, wasn’t fazed. “I don’t have any problem,” he said. “We see each other eye to eye—well, two eyes to their 16—but we get along swell.”

8. A HOUSEHOLD CLEANING AGENT PLAYED A PART IN WRANGLING THE SPIDERS.

“You can’t actually teach them to do anything,” wrangler Steven Kutcher told Entertainment Weekly. “You just watch what they do, then figure out how you can apply it to what you want them to do.” Still, he managed to come up with some solutions for controlling them: He discovered that the spiders hated Lemon Pledge—it gummed up their feet—and used lines of it on the set to control where they went; he also strung networks of wire, vibrating faster than the camera could see, to guide them. But sometimes, more extreme measures were needed. According to The New York Times,

To keep spiders in a relatively contained area, they are put to sleep with carbon dioxide, and tiny monofilament ''leashes'' are attached by wax to their abdomens. And for really complicated shots, minuscule steel plates are glued to the spiders with wax; electromagnets behind a wall then move them to the places where the script calls for them to be.

The wranglers would also sometimes chase the arachnids with hair dryers to get them to go where the camera needed them.

9. MARSHALL PLANNED HIS SHOTS VERY CAREFULLY.

“One of the things I learned in my second unit directing days is the only way it’s going to be scary is to include the spiders in the same shots with the actors,” he said. “So we’ve been designing the shots so when you start on a person you pan over, there’s a spider there, and the audience will know the spiders are very, very close to all the actors.”

10. THE ACTORS HAD TO BE PATIENT.

“This film takes a special kind of actor,” Daniels joked to The New York Times. “You have to realize from day one of shooting that the spiders come first. They're picked up first in the morning, they're first in the chair at makeup, they take lunch first. And they've also got the biggest trailer.'' 

The spiders didn’t always do what they were supposed to do on cue, or on the first try—so, Marshall told Entertainment Weekly, “You just have to keep shooting over and over again until they accidentally give you what you want.”

“You are basically waiting for the spider to get it right,” Daniels told the Orlando Sentinel. “And when he does, you better be great because that's the one [take] we are going to use.” Sometimes, they weren't even awake when the cameras were ready to roll: When Entertainment Weekly visited the set, the cast and crew had to wait for Big Bob to wake up. “This is the last time I work with insects,” Marshall said. “Next time it’s humans only.”

11. THE CREW HAD A “SPIDER LOTTO.”

The New York Times reported that one of the most often heard phrases on the set of Arachnophobia was “Spiders, take 10.” Marshall told the paper that sometimes the cast and crew had "a spider lotto; everyone puts $5 on the take they think is going to work. Twenty-one takes is the longest we've gone.” 

12. FILMING THE SCENE WHERE A SPIDER GETS STEPPED ON TOOK HOURS.

The safety of the spiders was paramount throughout the entire production, so for one scene where Goodman had to spray an arachnid with insecticide, then squash it with his boot, the production went to extreme measures: First, a dummy spider was sprayed. Then Goodman donned special boots with a hollowed out sole for the squash shot. “[The spider] would just curl up inside and wait for the next take,” Goodman told Entertainment Weekly. ”I swear, [Kutcher] was more concerned with the spiders than with us.” The sequence lasts under half a minute on screen but took hours to shoot.

13. A MECHANICAL BIG BOB DOUBLE WAS BUILT—BY A FUTURE MYTHBUSTER.

Even a painted up and tricked out spider wouldn’t be useable for all the shots. “He has to stalk Jeff Daniels; he has to stay in the right light, and if we waited for him to do that, we'd be here three or four months longer,” Marshall told The New York Times. "The main character had to become a creature, and no spider out there could give us the vicious, evil close-ups the script called for," added visual effects supervisor David Sosalla, "The evilest ones, with real ugly looking faces, were too tiny.”

So the production reached out to a Hollywood prop shop to build The General, a 15-inch mechanical Big Bob double—and it was created by none other than future MythBuster Jamie Hyneman. “Arachnophobia was one of the first films I did major effects for,” he said in 2014.

14. THE PRODUCTION SHOT THE TOUGHEST SCENE LAST.

Marshall saved the shooting of Arachnophobia’s climactic fight between Jennings and The General until the very end of production. “All the other actors have been sent home, they've been put on planes, they've been waved goodbye to, they've had parties thrown,'' Daniels told the Orlando Sentinel. “They were gone. It was like, ‘Hey, great, thanks a lot! Now, Jeff, let's go ... down to the basement.’” 

The scene, which involved fire, explosions, and many smashed bottles of fine wine, took two weeks of 13-hour days to shoot. Daniels spent two of those days pinned under a 250-pound wine rack, hurling bottles of wine at Big Bob while under strict instructions to not hit the spider—and, in fact, always miss it by three feet or more. 

“When you're lying under a 250-pound wine rack for a couple of days, it's tough to walk to your car at night,” Daniels told the Sentinel. “Movies have a way of saving those life-or-death stunts for last, so that if you lose an actor, it's a shame and it's horrible, and we'll all be there at the funeral, but at least we got our film shot."

15. DANIELS WAS NOT A FAN OF BIG BOB.

Throughout the Arachnophobia press tour, Daniels spoke openly of his animosity toward his big, hairy co-star—and we’re not talking about John Goodman. I had a problem” with Big Bob, Daniels told Entertainment Weekly. “Especially when the spider wranglers were off-camera wearing thick, heavy gloves, yelling, ‘If he comes after you, we’ll be jumping in right away.’ But meanwhile, it’s the movies, you know, and they’re going, ‘Let’s do it again. Let’s see if we can get him to crawl closer to Jeff’s hand.’ ... We had no rapport,” Daniels jokingly continued. “He’d rear up and hiss. They’d feed him a rat every weekend. It would be, ‘Have a good Saturday night, Bob. See ya Monday.”’

In an interview with Philadelphia's Daily News, Daniels recounted how Big Bob once blew a dozen takes: “I had to be great every time. Big Bob only had to be great once.” And when they were filming the climax of the film and a bottle broke near Bob, drenching the spider with wine, Daniels wasn’t that sorry—although filming did have to be delayed for a few hours to allow Bob to dry off. "The joke went that Big Bob was refusing to leave his trailer," Daniels recalled.

As for the Delenas? "I was OK with them,” he told Entertainment Weekly. "Though I’d rather they weren’t crawling on my face.”

16. THE MOVIE ORIGINALLY ENDED WITH A REFERENCE TO THE BIRDS. 

"There was one ending where we are standing outside after it's all over,” Daniels told the Orlando Sentinel in 1990. “It's like, ‘Wow, we're OK,’ and the family is all right. All of a sudden, one bird lands on the swing set and then another ... and we just turn and look. I think [executive producer Steven] Spielberg was the one who said, ‘Let's not do that. Let's just make it its own thing.’”

17. NO SPIDERS WERE KILLED DURING THE PRODUCTION.

When dead spiders were needed, the filmmakers used bodies of arachnids that had died of natural causes

18. IT WAS BILLED AS “THE FIRST THRILL-OMEDY.”

According to materials released with the film, that meant “a thriller with a sense of humor.” The Washington Post called the term “clumsy coinage,” while Entertainment Weekly dubbed it “awkward” and said in a review that it was “an awful word!—it sounds like somebody got sick from too many rides on the Whip.” It didn’t catch on.