The Macy's Thanksgiving Day Parade, normally a celebration of holiday spirit and American commercialism, has become the center of controversy as animal activists have begun loudly protesting the inclusion of a SeaWorld-sponsored orca float. According to the Christian Science Monitor, parade organizers have received letters from nearly 80,000 people demanding that SeaWorld's "Sea of Surprises" float, a 27-foot sculpture of the park's signature killer whale attraction, "Shamu," be struck from the parade.

The most recent debate over orcas—and the whales held by SeaWorld in particular—was sparked by the controversial documentary, Blackfish, which detailed the history of the killer whales in captivity and their numerous fatal encounters with park trainers over the years.

"It’s unfortunate that they’re going to have a float to promote what we now know is a very ethically questionable industry,” Emory University neuroscientist Lori Marino told the Monitor. “At this point, everyone knows that this is an issue, and the data and the science on how orcas fare in captivity is pretty unequivocal at this point.”

Macy's organizers, for their part, have said they are not responsible for such concerns. In an email to the Monitor, Macy's spokesman Orlando Veras stated that the parade "has never taken on, promoted or otherwise engaged in social commentary, political debate, or other forms of advocacy, no matter how worthy.”

SeaWorld is currently appealing a 2010 court ruling by the Occupational Safety and Health Administration (OSHA) that forced the park to pay a fine of $75,000 for exposing its trainers to a hazardous environment.

Read more about the deadly history of orcas in captivity in "The Killer in the Pool," by Tim Zimmerman