Q: What hunting methods does a praying mantis use to catch food?  Ry, New Hampshire, USA

A:  A small red caterpillar crawls blithely across the great, green expanse of leaf, unaware of the killing machine he nears.  The praying mantis, poised, also on the leaf, her camouflaged four twig-like legs spread out for stability, watches intently.  The end of her green abdomen curls up for balance; her forelimbs are cocked, ironically indicating prayer.  She leans toward the caterpillar.

She sways slightly like a leaf in a gentle breeze.  Her great triangular head swings on the stubby neck, tracking the clueless caterpillar. 

"The neck is quite short, but unusually flexible so the head can turn," emails entomologist John Meyer, professor at North Carolina State University.

She leans farther forward and lower still.  Suddenly, the strike — too fast for eye to follow — and she's got him.  She pinches her prey between segments of her raptorial legs, the spines biting in, pinning the squirming caterpillar, and eats delicately.

"With its excellent eyesight, patience and use of cryptic behavior, the mantis strikes with amazing speed at almost any animal its size, even small birds!" says Dan Feldman of the Colorado State University entomology department. 

"The mantid [mantis] uses two primary hunting methods," Feldman says.  It usually waits "motionless" until prey "comes within strike range" or, occasionally, pursues, in fluid slow motion, its hapless target until it gets within range.  The strike takes "30 to 50 thousandths of a second." 

Praying mantises and mantis shrimp, though evolved along entirely different paths, share the same spring-like strike mechanism.  Each stores energy in the leg or claw muscles and then releases it in a flash like a sprung jack-in-the-box.  This way, they achieve blurring speeds and great power — enough to shatter aquarium glass, in the case of the tiny mantis shrimp.

Praying mantises eat practically anything; one researcher (Frederick Prete) documented twenty-one species of insects, turtles, mice, frogs, birds and newts.  Typically they eat cockroach-type insects, and dote on soft-bodied insects like flies.

Over 1800 species dot the world, but most are concentrated in tropical regions.  Africa boasts 880 species, Asia 530, Oceania 165, the Americas 410 and Europe 24.  North America has 20 species, bunched (8) in Arizona.  The adults in North America range in length from 2 to 6 inches (5-15 cm).  A Sri Lankan species grows up to 10 inches (25 cm).

Further Reading:

Mantis shrimp spring into shattering action, WonderQuest

Compound eyes by John Meyer, North Carolina State University

Bug bytes by John Meyer, North Carolina State University

The praying mantis by Dan Feldman, Colorado State University

Praying mantis makes a meal of a hummer, Bird Watcher's Digest

International Wildlife encyclopedia, edited by Maurice Burton and Robert Burton

Prete, Frederick R. "Configural Prey Recognition…" Brain Behavior Evolution v3 (1990): 300-306.

Video of giant Asian praying mantis by exboyz04, YouTube

Q: If I am on the ground, how many miles away is the horizon?  Cheris13, Goose Creek, South Carolina

A:  It depends what's on the horizon.  The higher the object, the farther away we can see it. 

It's a cold winter's day here in Albuquerque, and I can see the sun shining on snow-capped Sangre de Cristo mountains, nestled on the horizon, about 75 miles (120 km) away.  Actually, these mountains rise about 8000 feet (2500 m) above terrain, so I can go farther away and still see them.  In fact, I should be able to see them from 120 miles (190 km), neglecting the effects of atmosphere.

With nothing rising tall on the horizon, it's a different story.  My eyes are about 5 feet 3 inches (1.6 m) above the ground, so I can see across flat terrain — plains or mesa — or an ocean, only about 3 miles (5 km), again neglecting the effects of atmosphere.

Further Reading:

Looking out the window of a high-flying jet, how far away is the horizon? WonderQuest

How far is the horizon?  Boat Safe Kids

Sangre de Cristo Mountains, Wikipedia

(Answered Jan. 22, 2006)