Cheetah's speedy stride
SMALL PRINT:WITH THE Olympics coming up, we could see a few world records smashed.
But when it comes to sprinting, the cheetah is nature’s gold medallist. A new study in the Journal of Experimental Biology sought to find out more about why the cats are so fast by comparing them to the less speedy but still fleet greyhound.
By comparing force plate and high-speed video data of galloping cheetahs and greyhounds, the researchers saw that the cheetah’s stride length and frequency, and how the cat supports a greater percentage of its body weight on its hind legs at high speeds (18 metres per second) could be factors that help it outrun the dogs.
At the other end of the scale, there are plenty that could overtake Greenland sharks (Somniosus microcephalus). A separate study used data-logging tags on six of the fish and saw cruising speeds of 0.34 metres per second with “bursts” of up to 0.7 metres per second.
“We showed that Greenland sharks swim at the slowest speed for their size among fishes studied to date, presumably because of the depressing effect of cold polar waters on locomotor muscle functions,” write the study authors in the Journal of Experimental Marine Biology and Ecology.
The term “sluggish” springs to mind, but their lack of speed doesn’t seem to lead to a lack of dinner – Greenland sharks apparently attack live seals.
So why does their prey not just swim away? The authors hypothesise that the slow-moving sharks might target seals that are sleeping in the water to avoid polar bears.