Migration is normally prompted by the instinct to survive such as the regular bird migrations spurred by the onset of winter in the Northern Hemisphere.

Yet in the case of killer whales, these gigantic ocean mammals, according to a new study, swims away from the freezing waters of the Antarctic to purposely shed its old skin and take on a new and shiny one.

Published recently by the British Royal Society's journal Biology Letters, the new study suggested that killer whales or Orcas embark on a more than 10,000-kilometre journey to search for a more suitable climate for their skin-changing routine.

Deviating from most migration patterns, Orcas, who mostly feed on penguins and seal pups, seek out the tropic temperature of the upper seas, with the research singling out the waters near Brazil and Uruguay as preferred destinations, to escape the punishing and below-zero chill of the Antarctic seas.

"We hypothesise that these migrations were thermally motivated," research lead authors John Durban and Robert Pitman of the U.S. National Marine Fisheries Service were quoted by Agence France Presse (AFP) as saying in the scientific report.

The two suggested that killer whales migrated to warmer waters in order to safely exfoliate, which they declared was not exactly ideal in the freezing waters down below where the high-speed swimming creatures could easily meet death while gradually leaving out their old skins.

According to AFP, Durban and Pittman initiated their observation on 12 Orcas, also known as Type B of the killer whale class, in January 2009 by tagging the water mammals with satellite transmitters that enabled them to map the whales' movement over the next two years.

"Our tagged whales followed the most direct path to the nearest warm waters north of the subtropical convergence, with a gradual slowing of swim speed in progressively warmer water," the two researchers reported on their study.

The study also observed that Orca departures were not motivated by regular routine such as the urge for a group hunt in order to launch a large-scale feeding frenzy for purported concentrations of seals and penguins.

Rather, the study surmised that the giant sea creatures were deliberately 'creating a more suitable environment' for their regular skin-shedding regimen, much in the same way that snakes replace their outer coverings though in a less spectacular manner.