The native peoples of North America call them blackfish. They’re the orcas, all too frequently referred to as killer whales in popular culture. That’s a wildly inapplicable term, according to a marine biologist who appears in Blackfish and says, “There is no record of an orca doing harm to a human in the wild.”

It’s a different case with captive orcas, a fact driven home in Gabriela Cowperthwaite’s powerful and controversial documentary about the frightening consequences of capturing and training these whales. One of them in particular, Tilikum, is responsible for two deaths at popular marine amusement attractions.

The movie also serves as an indictment of a giant family-oriented marine entertainment center, SeaWorld. (It’s appropriate at this point to dispel any notion about Blackfish’s suitability for children, despite SeaWorld’s family-friendly branding efforts. The film is seriously inappropriate for kids.)

Most documentaries come and go with little notice or impact, but Blackfish is an exception. SeaWorld wouldn’t participate in the movie but chose instead to aggressively challenge it in public, a decision some business journalists have questioned. And now the company has lowered its admission prices by a tenth.

Blackfish begins on a grimly disturbing note. With unsettling and surreal calm, a caller in Orlando tells a 911 operator that one of SeaWorld’s whales “ate one of the trainers.” This was Dawn Brancheau and the whale was Tilikum. He was acquired by the company 20 years earlier from a defunct West Coast marine park. Unknown to SeaWorld’s patrons or performer-trainers, Tilikum already had killed a teenage trainee. A careless inquest didn’t assign blame (Cowperthwaite talked to a couple of witnesses who were never even contacted by the authorities), and SeaWorld suppressed the facts. Nor was this an anomaly. The movie includes old video of two other horrifying, nearly fatal attacks by orcas at SeaWorld. As it usually does, SeaWorld blamed the victims. There have evidently been scores of whale attacks around the world.

But why, if the orcas aren’t naturally hostile? Blackfish devotes much of its time to arguing that these intelligent, socially organized whales suffer in captivity, and are often subjected to harsh adverse-conditioning methods to turn them into the equivalent of performing seals. Their depression festers and anger sometimes erupts.

Cowperthwaite also follows a federal job-safety suit against SeaWorld and relies heavily on the intermittent commentary of former trainers, only one of whom offers any support for their former employer. Their words are often moving as they express regrets about their possible complicity in the cruelty, deception and danger at SeaWorld’s facilities.

Blackfish is a compelling expose of commercial dishonesty and greed, but there’s a lot of that everywhere. It’s also an appeal to us to reexamine our relationship to nature and other species, one which has allowed outfits like SeaWorld to exploit our gullibility and the unfortunate animals.

Watch the trailer for Blackfish