| Tim Holt | ... | Lt. Cmdr. John 'Twill' Twillinger | |
| Audrey Dalton | ... | Gail MacKenzie | |
| Hans Conried | ... | Dr. Jess Rogers | |
| Harlan Warde | ... | Lt. Robert 'Clem' Clemens | |
| Max Showalter | ... | Dr. Tad Johns (as Casey Adams) | |
| Mimi Gibson | ... | Sandy MacKenzie | |
| Gordon Jones | ... | Sheriff Josh Peters | |
| Marjorie Stapp | ... | Connie Blake | |
| Dennis McCarthy | ... | George Blake (lab assistant) | |
| Barbara Darrow | ... | Jody Simms | |
| Robert Benevides | ... | Seaman Morty Beatty (as Bob Beneveds) | |
| Michael Dugan | ... | Clarke | |
| Mack Williams | ... | Capt. Masters | |
| Wallace Earl | ... | Sally (as Eileen Harley) | |
| Jody McCrea | ... | Seaman Fred Johnson | |
| William Swan | ... | Seaman Howard Sanders | |
| Charles Tannen | ... | Seaman Wyatt (radioman) | |
| Byron Kane | ... | Coroner Nate Brown | |
| Hal Taggart | ... | Davis, the resort owner | |
| Gil Frye | ... | Deputy Scotty | |
| Dan Gachman | ... | Deputy Brewer | |
| Milton Parsons | ... | Lewis Clark Dobbs | |
| Ralph Moody | ... | Watchman at Lock 57 | |
| rest of cast listed alphabetically: | |||
| John Carlyle | ... | Monster Victim (uncredited) | |
| John Close | ... | Deputy Larry (uncredited) | |
| William Forrest | ... | Admiral Greenhouse (uncredited) | |
| Joseph Hamilton | ... | The Other Lock Watchman (uncredited) | |
| Charles Herbert | ... | Boy with Morty's Cap (uncredited) | |
| Ralph Littlefield | ... | Gatekeeper (uncredited) | |
| David McMahon | ... | Patterson (uncredited) | |
| Sarah Selby | ... | Mrs. Simms, Jody's mother (uncredited) | |
Directed by | |||
| Arnold Laven | |||
Writing credits | ||
| David Duncan | (story) | |
| Pat Fielder | ||
Produced by | |||
| Arthur Gardner | .... | producer | |
| Jules V. Levy | .... | producer | |
Original Music by | |||
| Heinz Roemheld | |||
Cinematography by | |||
| Lester White | |||
Film Editing by | |||
| John Faure | (as John D. Faure) | ||
Casting by | |||
| Kerwin Coughlin | |||
Art Direction by | |||
| James Dowell Vance | (as James Vance) | ||
Set Decoration by | |||
| Rudy Butler | |||
Makeup Department | |||
| Abe Haberman | .... | makeup artist | |
| Olga Collings | .... | hair stylist (uncredited) | |
Second Unit Director or Assistant Director | |||
| Paul Stader | .... | underwater unit director | |
| Maurice Vaccarino | .... | assistant director | |
Sound Department | |||
| Charles Althouse | .... | sound recordist | |
| Joel Moss | .... | sound recordist | |
| B.F. Remmington | .... | sound recordist (uncredited) | |
Special Effects by | |||
| Robert H. Crandall | .... | special effects photographer | |
| Ted Haworth | .... | special effects design (as Edward S. Haworth) | |
| Augie Lohman | .... | special effects (as August Lohman) | |
Camera and Electrical Department | |||
| Scotty Welbourne | .... | photographer: underwater unit (as Charles S. Welborn) | |
| Paul Eagler | .... | process photographer (uncredited) | |
Costume and Wardrobe Department | |||
| Allan Sloane | .... | wardrobe supervisor (uncredited) | |
Music Department | |||
| Heinz Roemheld | .... | conductor (uncredited) | |
Other crew | |||
| Norman Bishop | .... | underwater technical advisor | |
| Virginia Mazzuca | .... | production assistant | |
| Harlan Warde | .... | dialogue director | |
| Pat Fielder | .... | production assistant (uncredited) | |
|
|
|
|
|
| Gorgo | Piranha | King Kong | Jaws | Dreamcatcher |
|
IMDb User Rating: |
IMDb User Rating: |
IMDb User Rating: |
IMDb User Rating: |
IMDb User Rating: |
| Full cast and crew | Company credits | External reviews |
| News articles | IMDb Horror section | IMDb USA section |
This rates up there as one of the better "giant monsters wreak havoc on mankind" movies that came out of the 1950s. The predators this time are overgrown snails/mollusks/caterpillar-like creatures that awaken from the pits of the Salton Sea after an earthquake shakes things up and charges them full of radiation. These monsters may appear of the dime store variety to those who aren't used to these "big bug" pictures, but actually they're pretty believable for a movie like this.
Some of the assets setting this feature apart from its relatives would be the serious treatment of the story, some good acting and characters (it's fun watching Hans Conried as the knowledgeable scientist), and a few impressive pre-JAWS ocean scenes (one of the female victims meets a fateful watery demise, for example). Also adding to the effectiveness are some creepy ravaged corpses, the likes of which weren't usually this prominent back in the day.