Scientists unravel a tale of sea lice and the whales they hitch rides on

For eons as they cruised the oceans of the world, right whales have played host to a harmless parasite. Apparently these "whale lice" did nothing but eat dead whale skin and form colonies on the enormous animals.

Distinctive patterns of whale lice clumping on the animals helped researchers identify individual whales, but that seemed about the extent of their usefulness to science.

Now researchers know whale lice also played another role, serving as accidental historians. Their genetics tell about whale family trees, indicating when the right whales split into three species. (They are called that because early whalers found them the "right" type to hunt.) They hint at the decimation

caused by whaling. "Lice" genetics even speak of the wanderings of possibly a single right whale that crossed the equator 1 million or 2 million years ago.

The tie between whale lice genetics and the history of the right whales is described in a paper published in the October issue of Molecular Ecology. University of Utah researchers and colleagues elsewhere spent five years on the project.

The paper is an expanded version of the honors thesis written by Zofia "Ada" Kaliszewska while an undergraduate student at the U. She is now a graduate student at Harvard University and is listed as the paper's main author.

The "lice" are not the kind of parasites that hang onto land animals and birds. They are related to skeleton shrimp that attach themselves to seaweed and sponges.

"It's easy to see how early whales would have picked them up," said the principal investigator, Jon Seger, professor of biology at the U. "Some would have accidentally jumped on whales when whales brushed their substrate."

Three types of whale lice live at different sites on the right whales.

These varieties of whale lice live nowhere except on right whales; they are transferred from whale to whale. Some cross from mother to baby when the calves are nursing; some jump ship to other whales when the big beasts come into contact.

The right whales once were a single species and are now three. When the team of scientists examined the DNA of the whale lice, they discovered that variations in the lice genetic material shows when the whales split into different groups.