Featured Research

from universities, journals, and other organizations

Peanut worms are annelids

Date:
March 8, 2011
Source:
Universität Mainz
Summary:
Recent molecular phylogenetic analysis has shown that the marine animals known as peanut worms are not a separate phylum, but are definitely part of the family of annelids, also known as segmented worms. This is a classification that seemed questionable in the past in view of the fact that peanut worms -- or the Sipunculidae, to give them their scientific name -- have neither segments nor bristles. The latter are considered typical characteristics of annelids, which include more than 16,500 identified species and to which our common earthworm belongs.

Sipunculus nudus of the group of Sipunculidae with a length of about 8 centimeters.
Credit: Copyright Dr Anja Schulze, Texas A&M University at Galveston, USA

Recent molecular phylogenetic analysis has shown that the marine animals known as peanut worms are not a separate phylum, but are definitely part of the family of annelids, also known as segmented worms. This is a classification that seemed questionable in the past in view of the fact that peanut worms -- or the Sipunculidae, to give them their scientific name -- have neither segments nor bristles. The latter are considered typical characteristics of annelids, which include more than 16,500 identified species and to which our common earthworm belongs.

Related Articles


"Our molecular data clearly demonstrates that there is no doubt anymore that the Sipunculidae should be classified as members of these segmented worms," explains Dr Bernhard Lieb of the Institute of Zoology at Johannes Gutenberg University Mainz (JGU). The results were obtained as part of a broad study in which the phylogenetic development and relationships within the phylum Annelida were analyzed in terms of basic molecular biology to be then re-evaluated. Participating in the project are the universities of Osnabrück, Potsdam, Mainz, and Leipzig, together with the Max Planck Institute of Molecular Genetics in Berlin. The results have now been published online in the journal Nature.

"The relationships between the various annelids with regard to both morphological and molecular biological aspects have been a matter of dispute," states Lieb. Segmented worms are the most prevalent of marine macrofauna -- their habitat ranges from tidal zones to the deep oceans. Usually, they have been divided into two main classes: the Clitellata, which have few bristles, e.g. earthworms, and leeches on the one hand and the Polychaeta, literally the 'many bristled', on the other hand. The evolutionary and deep branching patterns of annelid lineage are still the subject of on-going scientific debate, although it has become increasingly clear that other groups that had previously been classified separately, such as peanut worms and beard worms, are actually members of this phylum.

By means of identifying some 48,000 amino acid positions in 34 different representatives of the phylum Annelida, the research group headed by the universities of Osnabrück and Potsdam has put together the hitherto most detailed database for the family of segmented worms. This has enabled the group to re-evaluate and reconstruct the phylogenetic interrelationships and evolution of this extensive and highly diverse group of animals.

The molecular data on Sipunculus nudus -- the peanut worm -- gathered by the team in Mainz led by Bernhard Lieb shows that the genetic characteristics of the worm, which lives in sand and silt at the bottom of the sea, clearly indicates that it is a member of the annelid family. In evolutionary terms the peanut worm is likely to be a basal group that diverged very early during evolution. It is conjectured on the basis of the sparse fossil record that the annelids first appeared in the Cambrian Period, roughly 550-490 million years ago. "We assume that segmentation was a very early characteristic of the annelids and that the peanut worm has lost its segmentation during the course of evolution," clarifies Lieb.

Primarily, new DNA sequencing technologies, so-called next-generation sequencing (NGS), made such comprehensive genetic investigations become possible. The Illumina Hiseq2000 sequencer recently acquired by the Institute of Genetics at JGU can analyze vast amounts of data, and sequence up to 200 gigabases of DNA per run within a single week. This means that whole genomes can be sequenced in a relatively short time, opening up completely new avenues for wide-ranging research.


Story Source:

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


Journal Reference:

  1. Torsten H. Struck, Christiane Paul, Natascha Hill, Stefanie Hartmann, Christoph Hösel, Michael Kube, Bernhard Lieb, Achim Meyer, Ralph Tiedemann, Günter Purschke, Christoph Bleidorn. Phylogenomic analyses unravel annelid evolution. Nature, March 3, 2011 DOI: 10.1038/nature09854

Cite This Page:

Universität Mainz. "Peanut worms are annelids." ScienceDaily. ScienceDaily, 8 March 2011. <www.sciencedaily.com/releases/2011/03/110302184042.htm>.
Universität Mainz. (2011, March 8). Peanut worms are annelids. ScienceDaily. Retrieved December 18, 2014 from www.sciencedaily.com/releases/2011/03/110302184042.htm
Universität Mainz. "Peanut worms are annelids." ScienceDaily. www.sciencedaily.com/releases/2011/03/110302184042.htm (accessed December 18, 2014).

Share This


More From ScienceDaily



More Plants & Animals News

Thursday, December 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) — The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
Kids Die While Under Protective Services

Kids Die While Under Protective Services

AP (Dec. 18, 2014) — As part of a six-month investigation of child maltreatment deaths, the AP found that hundreds of deaths from horrific abuse and neglect could have been prevented. AP's Haven Daley reports. (Dec. 18) Video provided by AP
Powered by NewsLook.com
When You Lose Weight, This Is Where The Fat Goes

When You Lose Weight, This Is Where The Fat Goes

Newsy (Dec. 17, 2014) — Can fat disappear into thin air? New research finds that during weight loss, over 80 percent of a person's fat molecules escape through the lungs. Video provided by Newsy
Powered by NewsLook.com
The Hottest Food Trends for 2015

The Hottest Food Trends for 2015

Buzz60 (Dec. 17, 2014) — Urbanspoon predicts whicg food trends will dominate the culinary scene in 2015. Mara Montalbano (@maramontalbano) has the story. Video provided by Buzz60
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