Whale of a Mystery: Why Those Ribs?

Jennifer Viegas - Discovery News, While dissecting a pygmy right whale at The Museum of New Zealand Te Papa, scientists there discovered that the creature possessed ribs unlike those of any other whale. Only one other animal is known to have a similar set: the anteater.

The ribs suggest pygmy right whales are stiffer in the water than previously thought, moving more like fast torpedoes than undulating fish.

"The international research team that just completed the dissection determined that the whale's ribs were flattened and overlapping," Te Papa museum spokesperson Jane Keig told Discovery News.

Sentiel Rommel, a lecturer in oceanography from the University of Maine, participated in the project.

He explained that a small amount of flesh between each of the ribs allows the otherwise packed ribcage "to move as the whale breathes and also accommodates changes in volume that occur as the air is compressed by water pressure when the whale dives through deep water."

Rommel added that the ribs' wide, flattened structure has only been observed before in certain types of anteaters. Studies on anteater ribs have indicated that the rib arrangement helps to stiffen their bodies as well.

"So, possibly, a stiffer body has advantages in the way (pygmy right whales) swim, but this is purely speculative at the moment," he said.

Keig also mentioned that two ribs from the upper ribcage broke, and then roughly healed, sometime during the 7.5-foot-long infant whale's short life. She suspects they broke when the six-month-old whale was stranded at Spirit's Bay in northern New Zealand, where it eventually died.

"We do not know the exact cause of death because our scientists performed a necropsy and not an autopsy," she said. "There are many possible causes for stranding."

One possibility, for example, is that the young whale became weakened and disoriented by a bacterial infection.

Brian Beatty, an assistant professor of anatomy at the New York College of Osteopathic Medicine, recently conducted one of the largest ever studies of modern and fossil whalebones.

Beatty told Discovery News that the analysis of the pygmy right whale is important because this species "is an unusual animal," even among the already unusual baleens.

Baleen whales, as opposed to toothed whales, feed by filtering water across a large, comb-like baleen structure.

"Being such a rare animal and hardly understood in terms of its anatomy and histology, this new specimen will significantly add to our understanding of the relationships between the modern baleen whales," Beatty said.

Although the official necropsy on the whale has ended, Keig said Te Papa scientists are still stripping the bones of flesh and muscle. Eventually the skeleton will go on display at the museum.

SOURCE : Discovery News