The Greenland shark, known for its slowness, must wait for seals to sleep to catch them, according to new observations!
This is a shark which there is no need to fear … unless you fall asleep under water! Researchers have accurately measured the speed of the sleeper shark or the Greenland shark, known for his carelessness … Its cruising speed is 0.34 meters per second and, even when he is hunting, moving is not enough quick to catch its prey, like seals. Conclusion: he probably waits that they sleep so he can eat them, according to researchers!
The Greenland shark (Somniosus microcephalus) is a pelagic fish, living in Arctic waters over 500 meters deep. In the belly of this big fish that can reach 7 meters long, it has already found the seals or squid inside it. But how did he hunt them? Among the hypotheses: the ability to suck up fish with their mouth, or a sudden acceleration.
According to the study published by Yuuki Watanabe (Polar Institute in Tokyo, Japan) and colleagues in the Journal of Experimental Marine Biology and Ecology, it showed that, even when the languid fish embarks on a burst of speed in order to hunt, it is far too slow to catch a swimming seal.. Using the tag they placed on the backs of six Greenland sharks, the researchers calculated that the maximum speed of this shark which it reached 0.74 meters per second. Less than the speed of seals whic it is 1m per second (2mph/3km/h). Sharks could take advantage of the fact that seals sleep in water to escape the polar bear to give them a bite.
It was thought that Greenland sharks simply fed on the carcasses of dead seals on the seafloor.