"The largest animals ever to live on Earth"

Blue whales are returning to Alaska in search of food and could be re-establishing an old migration route several decades after they were nearly wiped out by commercial whalers, scientists say.

The endangered whales, possibly the largest animals ever to live on Earth, have yet to recover from the worldwide slaughter that eliminated 99 percent of their number, according to the American Cetacean Society. The hunting peaked in 1931 with more than 29,000 animals killed in one season.

The animals used to cruise from Mexico and Southern California to Alaska, but they had mostly vanished from Alaskan waters.

But several sightings of California whales in recent years off the coasts of Alaska and British Columbia suggest that the massive animals are expanding north again in search of tiny shrimp-like krill to eat, scientists contend in a recent article published in the journal Marine Mammal Science.

Blue whales can grow up to 100 feet long and typically eat 4 tons of krill a day during the summer.