Featured Research

from universities, journals, and other organizations

Velvet Worm Brains Reveal Secret Sisterhood With Spiders

Date:
July 25, 2006
Source:
University of Arizona
Summary:
Velvet worms, living fossils that look like a child's rendition of caterpillars, are more closely related to spiders and scorpions than to butterflies, according to new research. Known to scientists as onychophorans, velvet worms have been thought to be similar to the ancestors of modern arthropods, the jointed-legged creatures that includes insects. Fossils that look very much like today's onychophorans can be found in rocks 540 million years old.

Velvet worms, living fossils that look like a child's rendition of caterpillars, are more closely related to spiders and scorpions than to butterflies, according to new research.

Related Articles


Known to scientists as onychophorans, velvet worms have been thought to be similar to the ancestors of modern arthropods, the jointed-legged creatures that includes insects.

Fossils that look very much like today's onychophorans can be found in rocks 540 million years old.

"When I looked at their brains, I was shocked because I didn't expect to see what I saw," said Nicholas J. Strausfeld of The University of Arizona in Tucson. "I just felt from their organization that these looked like spider brains, that they had more in common with spider brains than with other arthropod brains."

Strausfeld, a UA Regents' Professor of neurobiology and the director of UA's Center for Insect Science, is a pioneer in using the architectures of cell arrangements within brains to tease out evolutionary relationships among arthropods, the animal phylum that includes all kinds of creepy crawlies, including insects, crustaceans such as lobsters and crabs, and spiders and scorpions.

Onychophora live in groups, defend territories and subdue their prey with sticky goo. The small, sometimes brightly colored, worm-like carnivorous creatures have lobed appendages and live in leaf litter in tropical areas.

"They are very difficult to approach with a pair of forceps because they squirt out this gluey substance that bungs up one's dissection tools. In the wild they use it to immobilize their prey," Strausfeld said of the 2-inch-long critters. "They're really quite extraordinary."

Strausfeld and his colleagues compared the brain architecture of onychophorans with a range of arthropods, including spiders, scorpions, dragonflies, bees, crabs, shrimps and centipedes.

"There are certain ground rules that seem to apply to all brain structures. If we look at the olfactory systems in an onychophoran, the architectural entities that define that system are the same as in an insect or a crustacean or a human being," he said.

"So if we look at these representatives of early brains, we might get insights about how brains evolved in the first place."

Understanding the evolutionary origin of onychophorans could be the key to understanding the evolution of arthropods.

For hundreds of years, biologists have derived evolutionary relationships between groups of animals on the basis of their appearances. In the latter part of the 20th century, new molecular biology techniques allowed biologists to sort out the relationships among animals by analyzing bits of DNA or protein.

Such molecular lineages showed that onychophorans share a common ancestor with all modern arthropods.

Strausfeld had begun a comparative study of the microscopic structure of insect brains in the mid-1990s. He expanded that to include the brains of other arthropods.

The work revealed to him that different types of insects had distinctly different brains: beetles had beetle brains, bees had bee brains, flies had fly brains. Other arthropods, too, had brains that were uniquely their own: spiders, scorpions, centipedes and crabs could all be told apart by their brains.

Onychophoran brains were initially a puzzle. But once he took a hard look he realized "there were structures in the onychophoran brain that looked like those in a spider brain." So he compared onychophoran brains with other animals thought to be related to spiders, such as scorpions and horseshoe crabs.

"In every case these animals had certain traits, certain characters in common that were different from characters shared among the other arthropods, the insects and crustaceans."

Strausfeld and his colleagues cataloged many aspects of the microanatomy of various arthropod brains. The scientists then loaded the information into a computer program designed to sort out lineages based on the degree to which degree traits are shared by a defined group of animals.

Contrary to what most molecular analyses had shown, the computer-generated lineage based on brain microanatomy showed that onychophorans and the spider/scorpion group were more closely related to each other than thought before.

Not much is yet known about onychophorans, at least compared with some other arthropods, Strausfeld said.

"The animal looks simple, but the brain is not simple. Onychophora have pretty complicated behaviors. Colleagues in Australia have discovered that they have fascinating rivalry behaviors, interesting group behaviors and group interactions. Their ecology and genetics are fascinating, and they have really weird sex."

Strausfeld said the new finding suggests that the arrangement of onychophoran brains is an ancient one.

"It's another window into how something very important seems to have appeared very early in life's history," he said. "The very important thing being the brain, a complex brain at that."

The research article is scheduled for publication in the August 7 issue of the Proceedings of the Royal Society B. The work was supported by the John Simon Guggenheim Memorial Foundation and the John D. and Catherine T. MacArthur Foundation.

Strausfeld's coauthors on the research article, "Arthropod phylogeny: onychophoran brain organisation suggests an archaic relationship with the chelicerate stem lineage," are Camilla Mok Strausfeld of the UA; Rudi Loesel of the Institut fūr Biologie II (Zoologie) der RWTH Aachen, Germany; and David Rowell and Sally Stowe of The Australian National University in Canberra.


Story Source:

The above story is based on materials provided by University of Arizona. Note: Materials may be edited for content and length.


Cite This Page:

University of Arizona. "Velvet Worm Brains Reveal Secret Sisterhood With Spiders." ScienceDaily. ScienceDaily, 25 July 2006. <www.sciencedaily.com/releases/2006/07/060725074159.htm>.
University of Arizona. (2006, July 25). Velvet Worm Brains Reveal Secret Sisterhood With Spiders. ScienceDaily. Retrieved December 22, 2014 from www.sciencedaily.com/releases/2006/07/060725074159.htm
University of Arizona. "Velvet Worm Brains Reveal Secret Sisterhood With Spiders." ScienceDaily. www.sciencedaily.com/releases/2006/07/060725074159.htm (accessed December 22, 2014).

Share This


More From ScienceDaily



More Plants & Animals News

Monday, December 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Christmas Kissing Good for Health

Christmas Kissing Good for Health

Reuters - Innovations Video Online (Dec. 22, 2014) — Scientists in Amsterdam say couples transfer tens of millions of microbes when they kiss, encouraging healthy exposure to bacteria. Suzannah Butcher reports. Video provided by Reuters
Powered by NewsLook.com
Brain-Dwelling Tapeworm Reveals Genetic Secrets

Brain-Dwelling Tapeworm Reveals Genetic Secrets

Reuters - Innovations Video Online (Dec. 22, 2014) — Cambridge scientists have unravelled the genetic code of a rare tapeworm that lived inside a patient's brain for at least four year. Researchers hope it will present new opportunities to diagnose and treat this invasive parasite. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
New Fish Species Discovered, Setting Record for World's Deepest

New Fish Species Discovered, Setting Record for World's Deepest

Buzz60 (Dec. 22, 2014) — A new species of fish is discovered living five miles beneath the ocean surface, making it the deepest living fish on earth. Jen Markham has the story. Video provided by Buzz60
Powered by NewsLook.com
Earthworms Provide Cancer-Fighting Bacteria

Earthworms Provide Cancer-Fighting Bacteria

Reuters - Innovations Video Online (Dec. 21, 2014) — Polish scientists isolate bacteria from earthworm intestines which they say may be used in antibiotics and cancer treatments. Suzannah Butcher reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins