Belugas and other toothed whales used their underwater speed, which is four times faster than the sound on land, to their advantage by creating echos. One whale fossil gives clues as to how the echoes were able to help them catch their prey using the sounds.
The blowhole, situated between the whales eyes, acts as their nasal passages. When underwater, whales use the air held in their blowholes to make vibrations. When these vibrations reach the jaw, they move to the ears when they are able to hears the echos. Studying how whales makes sounds is difficult, at best, since the tissues in the head do not remain in tact, like that of the skull, teeth, ribs and vertebrae.
Roughly a decade ago, a toothed whale skull was discovered in South Carolina that is said to be 28 million years old. Mace Brown, a College of Charleston’s Mace Brown Natural History Museum curator, gained access to the skull, so the new species of whale was named after him. It is called the Cotylocara Macaei. “I knew it was special then,” he said, remembering when he first saw the whale skull.
Research conducted on the skull was reported by anatomist Jonathan Geisler in the journal Nature on Wednesday. As a co-author of the study, Geisler was able to determine that air pockets in the skull that help date echolocation back as far as 32 million years ago. “It suggest echolocation evolved very, very early in the history of the group that involved toothed whales,” he said.
There are a few unique features about the new whale species that help it stand out from similar species. Bone density variations and deep air cavities that are located on top of the skull and on both sides of the snout, for example. Sea animals of today do not show the same characteristics, proving that they have evolved over time. Now they have much better developed muscular and skeletal structures.
Looking at other examples of whale fossils that have been recovered and studied, they have hinted at the way that whales used their vibrations and echos to hear, but not has offered as clear indications at the Cotylocara Macaei. The study on this whale fossil offered specific details about the blowhole and snout that indicate how the animal made sounds and how they evolved over millions of years. In fact, this specific study gives scientists more information to look at other whale skulls in comparison to its findings.
Since the entire face of the whale was not preserved, it is difficult to tell how it sent out or interpreted sounds, according to Geisler. From what they can tell, however, the whales did not need to use their eyes to locate prey. Instead, they paid attention to the echos and how they vibrated off of things in the environment. Assuming that were able to produce echoes that helped them see sheds light on how they got their prey and evolved into the great predators they are today. The research also suggests that the design of the whale skull shows the need to probe into the inner ear, since that is where the next answers may be found.
By Tracy Rose