Introduction

Phylum Nemertea, an enigmatic group of worms found in oceans worldwide and occasionally in freshwater and even a few on land. Commonly called ribbon worms, this phylum contains over 1100 identified species of predatory worms with a wide range of sizes; some as small as 10-30 mm, others ranging 50-100 cm, and then some recordings such as Lineus longissimus that has been known to reach 30 m or more (Gibson 1993.) Their talents can seem quite fantastic, as they are rather serious predators in their respective fields. Their primary attack is the release of a neuro-toxin on a stylet protracted by their most outstanding feature, an eversible proboscis.

Worldwide these creatures have evolved to suit their respective habitats, yet leaving few links between the evolved variants. Extreme diversity within the group further complicates the matter as many species taxonomically distance themselves to the point of seeming quite unrelated. Though extensive research has been done on the taxonomy of these creatures, due to poor collection habits many of their previous exploits have been largely misnomered. But a team on nemertean research led by Dr. Jon L. Norenburg is dealing with the problem.

Material & Methods

Distribution Data
Nemerteans can be found practically anywhere on the globe, thus their distributionary data must be stored and catalogued by a large system. This is where the nemertean Global Mapping System (or NGMS) comes into play. Originally a Java based program, it has necessarily evolved to utilize an ArcIMS server to display data to nemertologists worldwide and will shortly be accessible via the Nemertes web page.

Samples Preparation
The nemertean samples shown here were collected by various means but most all share the following method of sample creation.

• Begin with the Paraffin Method:

I. Fixation
II. Washing
III. Dehydration – replace all water in tissue with alcohol
IV. De-Alcoholization (Clearing) – since paraffin and ETOH react undesirably, the alcohol is replaced with a liquid that can dissolve the paraffin, such as xylene
V. Infiltration with Paraffin – paraffin wax applied and allowed to cool
VI. Un-Molding, Trimming, and Attaching to Block
VII. Sectioning – Barber Optics Microtome used to cut sections at desired thickness, sections band together in a string that is cut and placed on slides in Glycerin Albumen solution and allowed to dry on warming plate overnight

• Next Phase is Staining

Crandall’s Staining Protocol (Butvar B-98; Edwards, R. & Price, R.; Stain Technology, January 1982) with the *Norenburg modification.

• Completion

Upon completion of staining, the slides are ready to be checked, cover slipped, dried, and viewed. If stains are not as desired, repeats of certain steps may be done to compensate.

Results

Cross section of Prosorhochmus sp. in capturing program used to create computer images; purpose of sectioning this portion was to test for reproductive organs in anterior mid-body. A partially resorbed ovary noted above proves the organ is present (Nemerteans are known to resorb reproductive organs after being captive for a while).

Cross section of Tubulanus sp. This section shows two sections of inverted proboscis within the rhynchocoel. The proboscis of the group represented here has two nerve cords running along the proboscis. The proboscis epithelium is split into two major portions, the bottom being the more glandular region that secretes adhesive mucus used to latch onto prey.

Cross section of Balaenanemertes sp. This diagram shows many characteristics commonly found in Nemerteans such as the proboscis sheath (the wall of the fluid-filled rhynchocoel) and a specialized and highly efficient stomach. The proboscis of this group has 10-12 nerve cords. Noteworthy of this image is the blown up section that shows the multiple nerve cords found along the proboscis. Noteworthy of this section and specific group of nemerteans is that testes are always located close to the brain.

Image of Poseidonemertes sp. Seen here is the variant of nemertean that uses only a single stylet to subdue its prey. Replacements are produced in accessory pouches should the primary one be lost. To the lower right of the granular basis is a canal through with neuro-toxin is pumped around the stylet, when it pierces a prey, and into the wound (Stricker & Cloney 1981.)

Image of Drepanophorus sp. This is a variant of nemertean that has up to 15 tiny stylets in a row on a basis that is sort of like the keel of a boat (Kirsteuer 1973). One hypothesis is that they use this in a scraping action upon prey. There is an accessory stylet sac for each stylet on the basis.

Acknowledgements

The author would like to extend his thanks to the National Science Foundation for making this internship possible by funding the NSF PEET grant (DEB 9712463) to Jon Norenburg and Diana Lipscomb. Personal thanks go out to Dr. Jon L. Norenburg for being the proboscis of my nemertean experience. Special thanks given to Barbara Littman for carefully walking me thru all lab proceedings with infinite patience. Thanks are also given to Dr. Pam Roe, and Frank B. Crandall for their knowledge, insight, and interesting stories. A warm thanks is placed upon Mary Sangrey for being the ringmaster of my stay here, and also to Elisa Maldonado for aiding in the finer details of my stay. Background image by Digital Blasphemy.

Literature Cited

Gibson, R. (1993). Phylum Nemertea – Ribbon Worms. In: P. Mather & I. Bennett (eds) A coral reef handbook, 3rd edition, pp 84-87.

Kirsteuer, E. (1973). A new polystiliferous hoplonemertean, Curranemertes natans gen. et sp. n., from the Caribbean Sea (Nemertina, Polystilifera Reptantia). Zool. Scr., 2: 125-140.

Stricker, S. A. & Cloney, R. A. (1981). The stylet apparatus of the nemertean Paranemertes peregrinaits ultrastructure and role in prey capture. Zoomorphology, 97: 205-223.

ENTOMOLOGY

Sebastian Patino
Research Assistantships for Minority High School Students

"Databasing Moth Genitalia Facts"

Poster
Abstract / Summary
Letter

More RTP Class of '03 Links