While there are many hundreds of films with exclamation marks in their titles, the key reference point for the emphatic punctuation at the end of writer/director Pierce Berolzheimer’s Crabs! is surely Gordon Douglas’s Them! (1954). After all, much as Gordon Douglas’ myrmecophobic movie was pure 50s B-movie, and featured invertebrates unnaturally enlarged by radiation from early atomic tests, Crabs! begins with the collapse of a nuclear power plant’s cooling towers, as horseshoe crabs are seen swimming in the waters nearby. The accompanying explosions are realised through extremely cheap-looking computer-composited effects, which only adds to the impression that Crabs! comes with overt B-status, or whatever the modern Asylum/SyFy Channel equivalent might be.

Bizarrely the disastrous meltdown that would presumably ensue from these explosions is never again mentioned or explained in the film, much as, in a later scene, nobody comments on why high school students are dissecting domestic cats (!?!) in their science class, or how an adolescent boy who lives in a trailer could afford a top-secret military-grade experimental energy source (the “Amorium Clustergram”) sent to him in the regular mail.

All of which is to say that Berolzheimer is simply not interested in realism or narrative logic. Even the film’s title is a misnomer, given that, as one character will eventually point out, Limulidae or “horseshoe crabs” are not in fact crabs at all or even crustaceans. Still, the title will turn out to be a direct quote – including exclamation mark – from a screaming woman on the beach, half her face torn off by an “ocean demon”, and the sort of viewer inclined to quibble with this early victim’s imprecise grasp of nomenclature and taxonomy is unlikely to accept what comes next: an invasion of rapidly mutating critters (surreally mistaken – twice – for badgers) which chuckle impishly and even speak like Joe Dante’s Gremlins. Like the xenomorphs from the Alien franchise, they range from face- (or crotch-)huggers to toothy human-sized adults to massive, mecha-battling kaiju. You can try resisting this tide of absurdity, but better just to accept whatever it washes ashore in the totally unserious spirit intended.

All credit is due to Berolzheimer for making wheelchair-bound teen Philip McCalister (Dylan Riley Snyder) the film’s hero, as he combines scientific know-how and a MacGuffin-like power source to bring down the shell-covered hordes. In this, Philip is helped by his equally brainy girlfriend Maddy Menrath (Allie Jennings), her science-teaching mum Annalise (Jessica Morris) and Philip’s older brother Hunter (Bryce Durfee). Yet if Crabs! scores points for its positive portrayal of ‘handicapable’ Philip, it risks losing them in its grotesque othering of Philip’s fellow student Radu (Chase Padgett), who is the (barely) human receptacle for a comic collection of stereotypes to signify monstrous foreignness – even if he too in the end gets to play a not-inconsiderable part in saving the day. For what it is worth. Radu also gets to sing a crab-related theme song over the closing credits.

Over the course of Crabs!, Sheriff Flanagan (Robert Craighead), his deputy Hunter, the teacher Annalise and Philip himself are all shown smoking dope, while Radu ingests magic mushrooms. This is probably an index to the film’s ideal reception – but for those unable to get their pincers on hallucinogens for viewing purposes, moderate to strong inebriation will certainly help.

Crabs! plays at FrightFest at Home at 8.05pm on Wednesday 1st September.