Meet the jumping champions of the animal world
It's Leap Day! What better day to celebrate the jumping champions of the animal world?
From kangaroos to fleas, lots of animals get around by jumping. There are land mammals, sea mammals (think whales), reptiles, amphibians, insects and spiders who move this way. They're called saltatorial animals for their leaping habit.
We're not talking about just an occasional hop -- which you and I could do -- but jumping as the major means of locomotion, or getting from point A to point B (which I could definitely not do).
Are there any famous saltatorial critters in the suburbs? We may not have any leapin' lizards, but we've got lots of leaping frogs. If you've ever tried to catch a frog, you know that they can propel themselves to safety in a split second. There are a dozen species of frogs in Kane County, and most are endowed with large, powerful hind legs (the homely toad wasn't in line when they were handing out strong legs).
A great example of a native frog that can vault great distances into the air is the leopard frog. These spotted frogs are common around ponds and creeks in our area. If you approach a leopard frog, you'll hear a warning squawk, see a blur, then a splash in the water. They are quick as a wink.
Leopard frogs are great athletes, and they caught the attention of biologists Henry Astley and Thomas Roberts at Brown University. Astley and Roberts wanted to find out the secret to these amphibians' tremendous jumping ability.
Using leopard frogs as "guinea pigs" in the biomechanical research lab, the team of scientists made an important discovery: the secret to a frog's jump lies in the elastic, or stretchy, tendons. The tendon and muscle work like a catapult, releasing energy in a fraction of a second.
Leopard frogs are cool, but cooler still is the tiny cricket frog. This tiny frog is the amphibian Superman, able leap tall grasses in a single bound. Northern cricket frogs are only about one inch long, yet they can jump five to six feet. Southern cricket frogs, which live a little outside of our area, are ever better jumpers than their northern neighbors. The northern cricket population declined in recent years, but there are hopeful signs that cricket frogs may be jumping again in a wetland near you.
Grasshoppers and crickets
The next contestants in the jumping Olympics of the animal world are grasshoppers, crickets and kin. Walk along any grassy trail in summer and you'll see grasshoppers scattering right and left. With huge powerful hind legs, they launch from their perches in vegetation. Ground crickets and tree crickets also scurry by, jumping every which way.
Scientists who studied the locomotion mechanisms of a particular jumping insect, the Pygmy mole cricket, found that these guys can jump not only from land but from water as well.
Malcolm Burrows of Cambridge University specializes in the biomechanics of animal movement. He and his colleague, M.D. Picker, uncovered some pretty cool mechanisms in the Pygmy mole crickets. In their paper published in the Journal of Experimental Biology, Burrows and Picker reported that, "The hind legs are dominated by enormous femora containing the jumping muscles and are 131 percent longer than the body."
A pygmy mole cricket can launch from just one leg and attain distances 250 times their body length. Looking further, the researchers found "unique arrays of spring-loaded paddles and spurs" that allow Pygmy mole crickets to jump from the surface of the water.
Fleas have fascinated and frustrated people for ages. These pesky insects are famous for jumping from grass onto animal fur, from fur to the carpet and back again. They are well equipped for getting around this way: compressed bodies and hind legs packed with a special protein that provides the spring in their jumps. This "rubberlike protein," called resilin, provides 97 percent of the energy for a flea's jump, according to Boris Krasnov's "Functional and Evolutionary Ecology of Fleas."
There are many species of fleas, and they vary in their jumping ability. Some species jump 38 times their body length. In order to attain these distances, fleas accelerate so fast that they undergo up to 100 Gs, or 100 times the force of gravity. 100 Gs would knock us flat.
Taking leaping to yet higher levels is a small bug called a froghopper. Neither a frog nor a grasshopper, the froghopper is a plant-sucking insect of fields and prairies. There are many species of froghoppers, and they're sometimes better known in their youth as spittlebugs. The average size of an adult froghopper is barely .12 inches in length, but it can propel itself two feet.
Two feet may not seem like a big deal, but that's the equivalent of a human jumping more than 600 feet. The froghopper beats out even fleas in the high jump.
What makes froghoppers the champion jumpers of the animal world? Froghoppers have the power-packed resilin that fleas do, but there must be something else to take them the extra distance. Burrows and his research team at Cambridge University analyzed the mechanisms used by froghoppers when they jump. They discovered that froghoppers have mechanical gears -- perhaps the only true gears in the animal kingdom.
The gears are made of small, interlocking teeth that synchronize legs as they leap. Precise coordination is required for effective long jumps -- if one leg pushes out of sync the insect will veer to the right or left.
The researchers used high-speed videos and electron micrographs to analyze the mechanics of the jump. The tiny froghoppers were clocked at 8.7 miles per hour, with each leg moving within 30 millionths of a second of the other.
Burrows calculated that the froghopper experiences 400 Gs in each leap. You check out the amazing video at www.smithsonianmag.com/.
Jumping as a way of life makes sense for these animals. It's both an evasive tactic and a way to catch lunch. By comparison, we are big, smart bipedal mammals designed to run for food and for safety. We seemed to have abandoned running for sitting behind the wheel. Nevertheless, we can learn a lot from our saltatorial friends who can outleap us any day.
• Valerie Blaine is a naturalist for the Forest Preserve District of Kane County. You may reach her at email@example.com.