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United States Department of Agriculture

Agricultural Research Service

Velvetworm: a Living Fossil

Living Fossil Is Half Insect, Half Worm, and All Hunter

If you were the size of a cricket or pill bug you probably wouldn't want to cross paths with a velvetworm.

Photo: Velvetworm / Copyrighted © by Charles W. Brown, who kindly granted use of this image. Two to four inches long, this hunter would quickly capture you with a lasso of goo, fired from special glands on its forked head. Unable to move, you'd soon become its dinner. Enzymes in the goo would start dissolving you--for easier eating!

Photo: Dave Adamksi, shown here at the Instituto Nacional de Biodiversidad, Museum Santo Domingo, Heredia, Costa Rica. So says David Adamski, pictured here, of ARS' Systematic Entomology Lab, located at the National Museum of Natural History, Smithsonian Institution, Washington, D.C. The insect scientist first met the goo-shooting velvetworm while on a teaching trip in Costa Rica a few summers ago (click here for map).

He returned from the Central American country with six velvetworms for an exhibit at the museum's Insect Zoo.


Graphic: magnifying glassAdamski has collected many insect specimens for identification purposes, especially if they prove to be a new crop pest. The velvetworm, which doesn't pester crops, is among the weirdest, he says.

For one, it is something between an insect and a worm--like a millipede or centipede. Such creatures are called Onycophora (Onee cough-ora). With 14 to 43 pairs of legs--28 to 86 total--you'd think velvetworms move really fast.

Not so, says Adamski: "It's probably not something you'd see speeding along on the arthropod highway. But even though it's slow, it has a way of getting at the animals it preys on as food."

Graphic: Velvetworm spies a cricket / by Bill Johnson, ARS InfoGraphic: InsectWhen a velvetworm spies a tasty termite or cricket, for example, it fires a crisscross stream of goo at the insect's legs. This trips the insect up and traps it so the velvetworm can dine.

At night, the velvetworm is a lone hunter. By day, it takes shelter under rocks, logs or leaves with other velvetworms. At least, that's what scientists believe about this secretive creature.

Such behavior is perhaps one reason why velvetworms are great evolutionary survivors, and maybe even a missing link between insects and worms.

Photo: Coelacanth fishIndeed, they are considered "living fossils," like this Coelacanth fish, found in the Indian Ocean and coastal waters of Indonesia.

Graphic: DinosaurNathan Erwin, director of the museum's Insect Zoo, says velvetworms "go back in the fossil Graphic: Dinosaurrecord 500 million years. They're very ancient, and of course, they've outlived the dinosaurs."

Yet it wasn't until roughly 1825 that scientists discovered the velvetworm. One-hundred and seventy-five years later, there's still much to be learned about this living legend.

So when Adamski's specimens arrived at the Insect Zoo, researchers carefully watched over them. They wanted to learn as much as possible about the new arrivals.

One female velvetworm actually gave birth to several live young. Not many insects give live birth; most lay eggs, . Adamski says. Unfortunately, none of the offspring or their parents are alive today. "They're difficult to maintain in captivity," Dr. Adamski says. However, "even a dead specimen can give us a lot of information."

Graphic: SpiderHe has since preserved the velvetworms so his colleague Gerald Baker can examine the creatures' insides at his lab at Mississippi State University.

Photo: Tubercles on velvetworm / Thank you Dr. Eric Schabtach, University of Oregon!Mainly found in tropical forests, velvetworms get their names from rows of tiny knobs that cover their cylindrical bodies, much like the ones in this microscope image. These knobs are called tubercles (tuber culls). Graphic: Question marks

What exact purpose they serve is just one more mystery that is the velvetworm.

— By Jan Suszkiw, Agricultural Research Service, Information Staff.

Links

Graphic: ButtonCurious about Coelacanths? Then click here to visit a site by the American Museum of Natural History.


Graphic: ButtonWant to see more photos of Costa Rica, and its inhabitants? Click here and visit Dr. Charles Brown's page at Santa Rosa Junior College.


Graphic: ButtonCurious about Albertosaurus and other dinosaurs? Visit the Field Museum of Natural History in Chicago at http://www.fmnh.org/exhibits/dino/Cretaceous.htm


Graphic: ButtonLast but not least is a site by photomicrograher, Dennis Kunkel, formerly with the University of Hawaii's Pacific Biomedical Research Center in Manoa. His site, Dennis Kunkel Microscopy, Inc., also features cool images taken with a high-powered, scanning electron microscope. Check 'em out at: http://www.DennisKunkel.com

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Last Modified: 2/14/2011
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