SeaWorld told the Herald that the penguins handled the flight "very well" and were currently living in a climate-controlled area at the park.
The organisation's communications director David Koontz said SeaWorld were co-ordinating the transport of the birds on behalf of an independent institute which would carry out valuable research.
The emperor penguins would also be a part of the marine park's Penguin Encounter exhibit.
The EPA and Department of Conservation were consulted on the shipment because the penguins travelled through a New Zealand airport. But those government bodies said they had no power over the export of the birds from Antarctic territory outside of the Ross Dependency.
Cath Wallace of the Antarctic and Southern Ocean Coalition said the "plucking'' of baby birds from their natural habitat showed the difficulty of managing Antarctica's wildlife.
"Antarctica is a reserve for science and nature, not a place for [taking] things from their homes. I think the Minister for the Environment and the EPA need to get some better Antarctic expertise because we are doing nothing there.''
SeaWorld's proposal said the 10 birds - which are not listed as endangered - would be integral in a research project to determine lung and air sac volumes in emperor penguins.
Mr Koontz emphasized that the research would take place at an independent
organisation, the Scripps Institute of Oceanography in San Diego, not at SeaWorld. He noted that the removal of the penguins from Antarctica had been approved by the US National Science Foundation.
Asked why SeaWorld needed to import penguins for research when it had its own emperor penguin breeding programme, Mr Koontz said most of SeaWorld's penguins were too old to undergo anaesthesia, which would be required as part of the research.
Mr Tait noted that the American marine park was taking into captivity the same species which New Zealand authorities had recently committed significant resources and funding to release back into the wild.
"We note that Time magazine this month named Happy Feet the runner-up in their annual Animal of the Year list, and the unprecedented concern and efforts spent to try to save the New Zealand emperor penguin when it arrived in New Zealand, and to return it back to its home. SeaWorld do not intend returning the penguins after their 'research'.''
The SeaWorld brand has attracted criticism from animal rights groups because it holds most of the world's 50 captive orcas. Two people have been killed in its orca pools.