Under pressure from People for the Ethical Treatment of Animals and others, Southwest on Thursday said it would curtail its 26-year partnership with the marine park. That means three colorful 737s—Shamu Two, Shamu Three and Penguin One—will retire at the end of the year.
"Shamu," the orca for Southwest, has been flying since 1998, and as such is one of the most famous special liveries in North America," said Jonny Clark, a commercial pilot and director of TheDesignAir, a product and design website covering the airline industry.
"Southwest, being one of the longest lasting low-cost carriers, has historically treated its livery with a little more levity than regular mainline carriers, and actually started creating special liveries back in 1984," Clark told CNBC via email. "Since then, other carriers have started to follow suit, such as Alaska Airlines, with its dubbed 'salmon-thirty-salmon,' to promote the fact it carries some of the best and freshest salmon in the world as cargo on its planes."
Even before Southwest, other airlines were changing the game. "The most memorable and iconic paint jobs were those by airline Braniff," Clark said. "They really changed the playing field for aviation design. In 1973, Alexander Calder, (the) modern artist, was commissioned to run a series of liveries to celebrate the colors of their destinations."
The best airline designs for 2014 is topped by Hawaiian Airways and Fiji Airways, according to an annual competition at TheDesignAir.
For Southwest's two Shamus and its gentoo penguin (which made its debut only one year ago,) the three planes will return to traditional Southwest colors. That likely means a trip to Leading Edge Aviation, which has painted more than 7,500 aircraft for airlines including Southwest, Delta, United and UPS. Each plane will spend four to seven days with Leading Edge for stripping and sanding and ultimately 60 gallons of new paint, according to company statistics.
A company spokeswoman said she was unable to provide a cost estimate.
Southwest did not mention the animal rights protests when it announced the change Thursday.
"Southwest and SeaWorld have mutually decided not to renew their partnership when the contract expires at the end of the year," the companies said in a joint statement. "The companies decided not to renew the contract based on shifting priorities. Southwest is spreading its wings with new international service and increased focus on local market efforts. With an increasing international visitor base, SeaWorld is looking to focus on new and growing markets in Latin America and Asia, among others."
The companies will maintain its Southwest Vacations program operated by Mark Travel, Marilee McInnis, a Southwest Airlines spokeswoman said.
SeaWorld has been under increasing pressure to make changes since the 2013 documentary "Blackfish" alleged it mistreated some of its captive animals. First-quarter revenue and admissions were down at its parks in California, Texas and Florida.
Net revenue from admissions was $137 million in the first quarter of 2014 compared with $152 million a year earlier, according to the company's financial filings. For the same period, net revenue from food and merchandise at its parks dropped to $75 million from $86 million a year earlier.
Other companies, including British Airways, are continuing their relationships with SeaWorld despite the protests. "In common with many airlines and travel companies in the UK, we offer convenient vacation booking services to members of the public who wish to visit attractions such as SeaWorld," British Airways spokeswoman Caroline Titmuss said in an email to CNBC late Thursday. "We offer similar options for visiting theme parks and other places of interest across our global network."