*Law professors and African-American groups are criticizing People for the Ethical Treatment of Animals [PETA] for comparing whales being held at SeaWorld to “slaves.”

Last week, the animal rights group filed a lawsuit against SeaWorld, asking a federal court to declare that five wild-caught orca whales at SeaWorld are slaves — a supposed violation of the 13th Amendment.

The Thirteenth Amendment reads: “Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction.”

The lawsuit is the first time that a group has tried to extend Thirteenth Amendment protections to “nonhuman animals,” as PETA’s press release refers to them.

The five whales have been named plaintiffs in the case.

“All five of these orcas were violently seized from the ocean and taken from their families as babies,” said PETA President Ingrid E. Newkirk. “They are denied freedom and everything else that is natural and important to them while kept in small concrete tanks and reduced to performing stupid tricks. The 13th Amendment prohibits slavery, and these orcas are, by definition, slaves.”

The stunt has drawn the ire of legal scholars and African-American groups across the country. Project 21, a national conservative black leadership network, said in a release that many members were “amused and appalled” at the comparison.

“Oops! I just fell out of my chair. PETA’s comparison of SeaWorld and slavery insults the remains of hundreds of thousands of slaves who are buried across the American South,” wrote Project 21′s Deroy Murdock, a syndicated newspaper columnist. “To equate performing killer whales with human beings who suffered the worst possible exploitation short of actual genocide makes the jaw drop. Half of me wants to laugh. The other half wonders if I have been whisked from Earth to another planet.”

“For PETA to compare penning killer whales to human slavery would be hysterical if it wasn’t so offensive,” continued Project 21 spokeswoman Shelby Emmett. “Our ancestors were raped, whipped, taken from their families, stripped of their religion and culture and defined as property. This is a perfect example of how the left now defines everything as a ‘civil rights movement’ — diluting the history of slavery and human cruelty. If our children are taught SeaWorld is the equivalent to the plantation, how will they ever understand the evils of slavery? Sadly, it seems that PETA, like the plantation owners of our past, also think humans are animals.”

David Steinberg, a professor at the Thomas Jefferson School of Law in San Diego, characterized PETA’s claims as “patently, absolutely frivolous” in an interview with The Guardian.

“The 13th Amendment abolished the abhorrent, despicable practice of the slavery of human beings,” he said. “PETA is demeaning the integrity and humanity of people who were owned as slaves. That is outrageous.”