Article 3
Move over cheetah: Mite sets new speed record
This California critter would outrun all other land animals, if you scaled them down to its size
BY CAMERON WALKER (MAY 7, 2014)
SAN DIEGO — Tough luck, tiger beetle. A tiny mite found
in Southern California has just smashed your land-speed
record for animals.
At first glance, this mite may not seem so fast. It’s only
about the size of a sesame seed. Yet that would be one
fast seed: At top speed it can zoom at about 30
centimeters (11.8 inches) per second.
At its fastest, this mite can cover a distance 322 times its body length in a single second. The previous landspeed record holder, an Australian tiger beetle, moves at a more leisurely 171 body-lengths per second. And
the supposedly ultra-fast cheetah? It can manage short sprints at 93 kilometers (58 miles) per hour. That’s
fast, but the big cat covers a mere 16 body lengths or so per second.
If the mite were scaled to the size of a human, its speed would be equivalent to a person running at 2,092
kilometers (1,300 miles) per hour. That would mean it could easily outrun a moving car, high-speed train — or
even a commercial jet.
Jonathan Wright and Samuel Rubin reported the mite’s land-speed record last week at the Experimental
Biology meeting in San Diego, Calif. The species, Paratarsotomus macropalpis (PARE-uh-tar-SO-toh-miss MACro-PAL-piss), resembled blowing bits of dust when Wright first spotted them. The biologist works at Pomona
College in Claremont, Calif., about an hour’s drive from downtown Los Angeles. Rubin is a student studying
physics at Pitzer College, also in Claremont.
The mites don’t belong to a new species. Scientists discovered them
back in 1916. But until recently, no one seems to have studied the tiny
arachnids. People sometimes run across these mites skittering over
concrete driveways, rocks and sidewalks in Southern California.
Rubin collected some last summer for this study. He used a tool called
an aspirator to suck up and capture the tiny creatures without choking
on them. “The hose you breathe in through has a mesh filter on the
bottom, inside the chamber,” he explains. That way “you don’t inhale
mites.”
The researchers then turned the mites into film stars. In the lab, they recorded the animals on high-speed
video to zero in on how the mites move their legs and turn. They also filmed some mites in the field to catch
them barreling along at top speed.
From the footage, the researchers were able to calculate the mites’ record-breaking speed. They also saw that
the mites could accelerate and slow down rapidly. A mite can even manage sharp changes in direction —
sometimes pivoting on its third leg to make especially tight turns.
Some mites are predators. Owen Seeman says there are even species that are as fierce as lions in the
savannah. Those mites stab their prey with their mouthparts, ripping open their prey’s belly. Then they vomit
digestive enzymes into the prey’s carcass and suck their victim dry. (Only its shell is left behind.) Seeman
works at the Queensland Museum in South Brisbane, Australia. As an acarologist, he studies mites and ticks.
While there’s still little known about the eating habits of P. macropalpis, the researchers say the need to chase
down prey may explain why it evolved such high speeds. But this tiny critter might not top the podium for
long. “I wouldn’t be surprised if there are other mites that are faster,” says Wright.
Jürgen Otto has studied closely related mites in Australia. He says the Californian mite’s speed record is
interesting. But even more importantly, its swift propulsion “probably raises questions about muscle
functioning and physiology.” Physiology is the study of how an organism functions, from the cellular level up
to full-body motion. Otto is an acarologist with the Australian Government Department of Agriculture, based
in Sydney.
Another mite in the same family, called Anystis baccarum, can be found living in many places around the
world. These tiny red animals are often seen running atop picnic tables and other surfaces. Like their evenspeedier California cousins, these mites, too, “move at an unbelievably fast rate, with their little red legs
whirring like the Roadrunner,” says Seeman.
The Californian mites can “move faster than their skeletal muscles should be able to work,” observes Wright,
of Pomona College. He says that finding out more about the wee animal’s biomechanics — how its body
propels it — could help engineers develop ultra-fast new robots and other devices.
But speed isn’t the animal’s only fascinating trait. “The mites are also very small and light,” says Rubin. He’s
the student who led much of the fieldwork. Mimicking the mites’ technique “could be used to engineer
smaller and lighter technologies,” he says. Rubin suspects mites could inspire not only robots that can work in
small spaces but even the development of new prosthetic body parts.
Being a speed demon is not this mite’s only super-power. It’s also a heat freak. Most animals can’t survive
temperatures above 50° Celsius (122° Fahrenheit). But the Californian mite zips along even when the heat hits
60 °C (140 °F). The researchers want to understand how this mite continues to function in such brutal
conditions.
Interestingly, the mite’s close Australian relatives also love it hot, notes Otto. At room temperature, those
mites dig into the sand, lay on their backs and stop moving. Only when he lowered a lamp to warm up the
sand did they perk up — all the way up.
In fact, Otto observed, the mites seem to move at only two speeds: a racing pace or full stop. “They don’t
seem to have medium gear,” says Otto. “They are incredibly fast or virtually immobile, never in-between.”
IPS Article 3 Questions
1. What is the top speed of the mite studied in Southern California and what is the “human
equivalent” speed?
2. Explain how the scientists in this experiment managed to experiment on the mite so
they could record the speed at which it was moving.
3. Why do the scientists believe the mite has evolved such high speeds?
4. What are three other characteristics of the mite that the study found interesting?
5. Explain, using your own reasoning, how this research may benefit developments in
technology.