A humpback whale. Courtesy NOAA

A San Diego State University graduate student has advanced  understanding of the development of baleen in whale species like the humpback, the university announced Wednesday.

Baleen is a filter-feeder system inside the mouths of baleen whales that allows them to filter out krill and other small animals from ocean water.

Previous research has found that although baleen whales do not have teeth as most mammals do, fetal whales develop what are called teeth germs — tiny remnants of teeth from the whale’s evolutionary predecessors that were similar to hippopotamuses or cows.

Agnese Lanzetti researched baleen whale teeth germ development, with the help of SDSU biologist Annalisa Berta. Museums in San Diego, New York, Los Angeles, Austin, Texas and Copenhagen all donated whale specimens. Lanzetti’s research found teeth germs present in fetuses as small as seven inches long. Humpback whale jaws contained as many as 40 tooth germs on each side, all less than half a millimeter in size.

“It’s not an area that there’s a lot of research on,” Lanzetti said. “It unites an important aspect of biology — which is development — and evolution.”

Lanzetti used an advanced CT scanner, which produced three-dimensional images with clarity similar to dissections. Lanzetti and other researchers hypothesize that the teeth germs have not disappeared, in spite of millions of years of evolution, because the proteins that trigger their development are also responsible for baleen development.

Lanzetti’s research was published in the journal The Anatomical Record, Advances in Integrative Anatomy and Evolutionary Biology.

“For the first time, scientists now have a better understanding of the development of baleen, important in the evolutionary success of these whales, since it enabled them to filter enormous volumes of water and prey during bulk feeding,” Berta said.

–City News Service