Orca (photo credit: kckeliner)
Recent results from tagging killer whales in the Antarctic has thrown up some interesting possibilities. It appears that killer whales make quick short trips up from Antarctic waters into the warmer waters of the tropics before immediately turning around and heading back south.
The researchers from the NOAA National Marine Fisheries Service suggest that this short duration trip is all about killer whales improving their skin condition. The pattern of this long distance duration did not match the patterns of whales who migrate to give birth or for feeding strategies.
Could killer whale migration be to improve skin condition?
One of the notable piece of evidence that the scientists have used to determine that the trip may be for almost medical or cosmetic reasons in the removal of a layer of algae from their skin after the trip.
“The whales are traveling so quickly, and in such a consistent track, that it is unlikely they are foraging for food or giving birth,” said John Durban, lead author from NOAA’s Southwest Fisheries Science Center in La Jolla, California. “We believe these movements are likely undertaken to help the whales regenerate skin tissue in a warmer environment with less heat loss.”
Antarctic killer whales often have a yellowish coating over their skin made up of algae and diatoms. When the whales return from their trip to the sub-tropics this layer has gone and the marine scientists believe that this shows the upper layers of skin – the epidermis – has been shed.
First long distance migration of a killer whale recorded.
The discovery was found after 12 killer whales were tagged and the journeys of 6 of them were closely followed. One of the killer whales was followed as it migrated from the Antarctic all the way to the southern coastal waters of Brazil – a round trip distance of about 5,000 miles. The complete return journey took just 42 days and was the first known case of a long distance migration for a killer whale.
The tracking revealed that while there were no major changes in direction of the migrating whales through the trip the killer whales did swim slower in the warmer waters. This has led the marine scientist to consider that the whales are taking advantage of the warmer waters to reduce heat loss as their skin layers regenerate. They also suggest that other whale species may also undertake this form of migration.
All 6 whales that were tracked on the migrations followed the same route to the southern Atlantic Ocean by taking a path to the east of the Falkland Islands before terminating either off the coast of Brazil or Uruguay.
External sites:
Biology Letters: Antarctic killer whales round trips.
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