Pygmy Right Whale Goes Under Knife

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In the wake of international buzz generated by a certain half-ton colossal squid last week, scientists and staff at The Museum of New Zealand Te Papa Tongarewa yesterday began the careful dissection of another rare marine specimen: a pygmy right whale.

Whale experts from around the world have convened at the museum for the event, which marks only the second time a major anatomical examination of a pygmy right whale has taken place. The first dissection was facilitated at the same museum in 1996.

“This is an incredible opportunity for Te Papa to host an international collaboration of leading whale scientists in an investigation of such a rare and unusual species from this region,” said Anton van Helden, the museum’s marine mammals collections’ manager and leader of the project.

Already they’ve determined the male infant whale was riddled with at least 12 cookie-cutter shark bite marks, which don’t appear to have caused its death.

The whale was stranded in northern New Zealand waters, where it died of unknown causes. It was then sent to the museum by agreement of local Maori tribes and the country’s Department of Conservation.

The researchers hope to solve at least two mysteries about this smallest baleen whale, which is most often found around New Zealand and southern Australia.

The first is how it fits into the whale family tree. Although the head of this species looks like a mini-version of a right whale head, it’s not believed to be closely related to its much larger namesake.

There is no fossil record for pygmy right whales, which possess more ribs than any other whale species, despite the fact that they only grow to about 21 feet long.

In comparison, right whales can grow to 50 feet, and it’s not uncommon for blue whales to reach 80 feet. This little fellow was just 6.5 feet long when he died.

The other mystery is how this species vocalizes. Joy Reidenberg, a comparative anatomist from Mount Sinai School of Medicine in New York, traveled to New Zealand for the dissection and has already begun to investigate the whale’s larynx.

She explained to Discovery News that whale larynxes, like those of humans, generally have vocal cords that produce sound.

“The difference is that they are not oriented in the same way,” she said. “In humans, they are perpendicular to airflow, so when they close together they stop airflow.

In whales, the vocal folds are parallel to airflow. Their orientation allows them to regulate the air in and out a reservoir called a laryngeal sac.”

When the sac expands in whales, it allows air to be shunted between it and the lungs, she explained.

This permits more efficient extraction of oxygen from the limited volume of air, because it turns over what scientists call “respiratory dead space,” or air not in contact with lung tissue.

In the process of shunting air, pygmy right whales may also be vibrating the vocal folds to make noise. By exhaling into the sac, they are also pushing air between the vocal folds, causing vibrations that make sounds.

Repetitive shunting allows air to be “recycled” inside the whale, allowing it to continue making sounds for a long time while submerged.

Reidenberg said she “expects to find that the laryngeal sac is asymmetrical, which is unusual in baleen whales.”

It’s not yet clear, she added, whether this is an elaboration of the midline sac position of other whales, or is closer to the ancestral condition of paired sacs, except that one has been lost.

“Answering this question may help us understand evolutionary relationships between different species of whales,” she said.

The dissection is expected to continue for the rest of the week.

Source: discovery.com