According to a recent study conducted by researchers at the University of Hawaii, in collaboration with scientists from the University of Tokyo, some species of floaters.
The species of sharks that have the buoyant ability are the prickly shark and the six-gill shark.
The study suggests that these sharks have to swim harder if they want to go downward into the water. The researchers say that to glide uphill, the sharks can glide without needing to use their tails.
Usually, sharks are negatively buoyant, meaning that if they stop swimming they sink into the water.
Sharks’ skeletons are cartilaginous, which means they are denser compared to bone skeletons. Their ability to float is given by their large liver, which is filled with oil.
However, most sharks are not positively buoyant and can sink if they don’t swim continuously.
Previous studies have shown that some sharks that live deep in the oceans might be neutrally buoyant, which helps them save energy in a harsh environment.
Carl Meyer, a researcher at the University of Hawaii’s Institute of Marine Biology and lead author of the study, explained that the discovery of positive buoyancy in these species of shark was unexpected.
Meyer said that his team needed to run two sets of experiments in order to confirm that some species of sharks are floaters.
The researchers placed on the sharks special accelerometers data loggers in order to measure how they swim up and down in the deep sea.
According to the scientists, these devices are similar to flight data recorders and provide information like the speed with which the sharks swim, the frequency of their tail beat, their heading and their body orientation.
Using this data, the biologists were able to determine if the sharks were negatively, neutrally or positively buoyant.
Also, the researchers managed for the first time to place a camera on a deep-sea shark to learn more about their natural habitats.
According to Meyer, the camera revealed images of “alien-looking reef” and invertebrates that live deep in the waters.
The researchers said that during the day the sharks live in deeper waters and by night they swim closer to the surface.
Image Source: therenewableplanet