The People for the Ethical Treatment of Animals (PETA) have sued SeaWorld marine parks arguing that the park was keeping whales as slaves and that the animals should be set free under America's 13th Amendment.

The animal rights group filed suit against the marine park last week contending that killer whales were captured from the sea and forced to perform tricks for their captors.

"It's the first case in the history of the US that seeks to extend constitutional rights to living, breathing, feeling beings who happen not have been born human," PETA's legal counsel Jeff Kerr said in a press statement.

"The case is based upon the plain text of the 13th Amendment, which outlaws the condition of slavery, without any reference to any particular class of victims and without reference to persons."

Kerr argued that SeaWorld's whales suffered in their captivity in the marine park and that they were forcibly ripped from their family in the wild and forced to live in the "equivalent of concrete bathtubs".

The captive whales are forced to perform demeaning tricks for the marine park and that they are turned into breeding machines so Sea World can have more performers.

The lawsuit has caught flak from African-American groups for comparing the Sea World whales to slaves. Project 21 a U.S. black leadership network said in a press release that many members were "amused and appalled" at the comparison.

Meanwhile law professor David Steinberg has called the lawsuit "patently, absolutely frivolous" in an interview with the Guardian.

This is hardly the first time PETA has captured media attention with their advocacy efforts. From provocative ads to grandiose publicity stunts, the animal rights group has drawn more than its share of publicity.

Here are top seven publicity stunts PETA has done in the name of fighting for animal rights.

Lawsuit