JUL 19, 2017 06:48 AM PDT

Why Do Some Sharks 'Shrug' Their Shoulders When Swallowing?

Not all sharks swallow their food in the same way, and researchers from Brown University are starting to take notice.

A new study published in the journal Proceedings of the Royal Society B reveals how bamboo sharks exhibit a distinct gesture when swallowing their food: a shrug of the shoulders.

A bamboo shark in its natural habitat.

Image Credit: Steve Childs/Wikimedia Commons

While bamboo sharks were feeding, the researchers used X-ray Reconstruction of Moving Morphology (XROMM), which is a fancy way of saying CT scans and high-resolution moving X-rays combined into a single package, to capture the behavior. XROMM was developed by Brown University to study biomechanics and see how bones and muscles move and interact with each other.

In particular, they noticed a slight 11º swinging motion of the shoulder girdle, a U-shaped system of bones, cartilage, and muscles that scientists once thought served no real purpose in sharks:

An illustration of how the bamboo shark's shoulder girdle "shrugs" as it swallows food.

Image Credit: Camp et. al.

Almost like saying “IDK," the shoulder girdle appears to ‘shrug’ while the food moves from the front of the mouth further into the digestive tract. Without a doubt, it was having an impact on the movement of the food.

“They have this long pharynx, and they have to keep food moving down it,” study lead author Ariel Camp explained. “We think this is part of a ‘hydrodynamic tongue.’ Sharks and fishes that don’t have a tongue control the motion of fluid within their mouths to manipulate food.”

Related: Man punches hammerhead shark to death and gets what he deserves

The study goes on to explain how this slight movement creates a powerful suction effect that helps the food get where it needs to go for digestion to take place. The process appears to be necessary since bamboo sharks lack a tongue, just like several other fish do.

Not only was this an important lesson learned about the shoulder girdle in bamboo sharks and potentially other suction-feeding fish, but it could pave the way for additional research into how the structure evolved in sharks.

“The girdle shows up [in the fossil record], around the time that jaws evolved,” Camp continued. “We aren’t sure exactly what structures it evolved from or how that happened. Part of understanding that history is understanding what were the functions this structure had to carry out.”

Related: This might be the world's first-known great white shark nursury

It goes without saying that Brown’s XROMM technology played a significant role in discovering this fascinating clue, but there’s still so much to learn if we are to understand how the shoulder girdle works. A key detail is to identify whether it behaves in the same manner in other fish species with similar suction-feeding habits.

Source: Brown University

About the Author
  • Fascinated by scientific discoveries and media, Anthony found his way here at LabRoots, where he would be able to dabble in the two. Anthony is a technology junkie that has vast experience in computer systems and automobile mechanics, as opposite as those sound.
You May Also Like
JUL 07, 2018
Videos
JUL 07, 2018
Can Sending Plants to Space Reveal a Cancer Treatment?
When plants are grown in a totally different environment, it may stimulate new effects....
JUL 09, 2018
Plants & Animals
JUL 09, 2018
Radio Tracking Could Help Control Asian Hornet Populations in the UK
Asian hornets have become a significant problem in the United Kingdom. These pesky insects feast on honeybees and other vital pollinating insects, and thei...
JUL 10, 2018
Plants & Animals
JUL 10, 2018
Spiders May Use Electric Fields to Go 'Ballooning'
Spiders are known for having eight legs, but as it seems, these arthropods can sometimes fly using a technique known to the scientific community as ‘...
JUL 23, 2018
Plants & Animals
JUL 23, 2018
These Sneaky Monkeys Scavenge Nuts That Are Pre-Cracked by Predators
Throughout West Africa’s Taï National Park, the miniature mangabey monkey scavenges on the remnants of hard nuts that have been cracked open by...
AUG 13, 2018
Plants & Animals
AUG 13, 2018
Orca Mother Stops Mourning Dead Calf After 17 Days
Orcas are notorious for mourning their deceased loved ones by lugging the lifeless bodies around with them for extended periods of time, but a recent incid...
SEP 20, 2018
Videos
SEP 20, 2018
A Plant 'Nervous System' is Found
Learn more about how plants communicate....
Loading Comments...