Paranemertes peregrina Coe, 1901

Common name(s):  Purple ribbon worm, restless ribbon worm, wandering ribbon worm, mud nemertean

Synonyms: Paranemertes peregrina
Class Enopla 
Order Hoploonemertea 
Suborder Monostilifera 
Family Emplectonematidae 
Paranemertes peregrina from Padilla Bay mudflats.  This individual is about 8 cm long.
(Photo by: Dave Cowles, July 2009)
Description:   As a member of Class Enopla, the mouth and proboscis pore are united and at the anterior tip of the head (photo) and the proboscis is armed with a stylet.  In P. peregrina the stylet has a substantial shaft with helical grooves and ridges.  The proboscis sheath is more than 1/5 the length of the body.  Typically there are 2-3 sacs of reserve stylets, with about 4 stylets in each sac.  Has numerous ocelli, but these do not extend behind the cerebral ganglia.  It does not have a statocyst.  The species does not usually live commensally with other species such as crustaceans or clams.   Dorsal surface is brown to purplish-brown (sometimes orange-brown) and the ventral surface is yellow to creamy white.  There is a lighter dorsal band near the borders and back of the head which extends across the posterior groups of ocelli (about 5-12 ocelli on each side).  The tail may be pointed.  Up to over 25 cm long but usually 6-15 cm.

Note:  Coe (2005) described two morphological types, one of which has strong spiral fluting on its stylets and is brownish dorsally, the other of which has little if any spiral fluting on the stylets and is more purple dorsally.

How to Distinguish from Similar Species: Emplectonema purpuratum may also be purple or brownish-purple but it is much longer and often has light brown specks.  Paranemertes sanjuanensis is similar in structure but is colored pale orange to flesh color.

Geographical Range:   Japan; Kamchatka; Aleutian Islands, Alaska to Ensenada, Baja California, Mexico

Depth Range:  Mid and low intertidal; shallow subtidal

Habitat:  Under rocks and under algae on wave-swept shores; or in the Pacific Northwest most commonly within or on muddy sediments or under stones in quieter environments.

Biology/Natural History:   This common species feeds on polychaetes, especially nereids, at low tide.  At high tide it remains mostly under cover but it is often seen crawling along rocks or mud, hunting during early-morning or nighttime low tides.  It can swallow prey slightly larger than itself.  In Washington a primary prey species is the small nereid Platynereis bicanaliculata which builds small tubes on Ulva, while in Alaska Nereis vexillosa is common prey.  Many Nereids show strong escape behavior after coming in contact with P. peregrina.  It seems to need to actually physically contact prey in order to detect its presence.  On contact with nereid prey, P. peregrina pulls its head back and everts its light-colored proboscis, which wraps around the prey.  The prey is soon paralyzed, probably by the alkaloid neurotoxin anabaseine from the stylet or from posterior proboscis glands.  P. peregrina then swallows the nereid.  After feeding it follows its own slime trail back to its burrow.  It eats about one prey worm per day and seems to reuse its stylet on multiple prey.  It can readily be induced to attack nereid worms in a laboratory dish.  It sometimes also preys on nephtyid, syllid, or spionid worms as well.

Exposure to fresh water may trigger eversion of the proboscis.  In many populations, many more females are found than males.  Spawning is mostly in spring and summer but may extend through the fall and into winter.  Populations in any one place tend to spawn within about a month of each other.  The orange-brown eggs are deposited singly or in gelatinous clusters and hatch in about 3 days.  Worms live about 1 1/2 years.

Some evidence suggests that anabaseine may be useful against Alzheimer's disease in humans.



 

References:

Dichotomous Keys:
  Carlton, 2007
  Flora and Fairbanks, 1966
  Kozloff, 1987, 1996

General References:
  Brusca and Brusca, 1978
  Johnson and Snook, 1955
  Kozloff, 1993
  Lamb and Hanby, 2005
  MacGinitie and MacGinitie, 1949
  Morris et al., 1980
  Niesen, 1994
  Niesen, 1997
  O'Clair and O'Clair, 1998
  Rickets et al., 1985

Scientific Articles:

Web sites:


General Notes and Observations:  Locations, abundances, unusual behaviors:

Head
This view of the head shows the lighter colored band along the edge of the head and across the back of the head.  The most posterior clusters of ocelli are near the posterior end of the band along the border.
 

Mouth

This view of the front of the head (contracted, alcohol-preserved specimen) shows the combined mouth and proboscis at the front of the head.
Photo by Dave Cowles, March 2010


The following set of photos showing Paranemertes peregrina attacking a Nereid worm in the mid to high rocky intertidal were taken by Rebecca Kordas at Eagle Cove on the SE side of Salt Spring Island, British Columbia on Sept 15, 2009.  Rebecca is from the zoology dept at the University of British Columbia.  Salt Spring Island is SE of Vancouver Island.  
Capturing nereid 1Capturing nemertean 2
When Rebecca first encountered the pair, the nemertean had already extended its proboscis and contacted the nereid worm as seen above.  The nereid was struggling and trying to crawl away into a nearby crack, pulling on the nemertean's proboscis.  The proboscis was not wrapped around the nereid's body but it appeared to be sticking to it.  
Nemertean with extended proboscisThe injured nereid
After the nereid thrashed back and forth some more it managed to shake off the nemertean's proboscis, which was slowly drawn back inside the nemertean (left).  The nereid's body, meanwhile, appeared damaged and flattened in the region where it had been contacted by the proboscis (right), but eventually it crawled away.



Authors and Editors of Page:
Dave Cowles (2009):  Created original page
CSS coding for page developed by Jonathan Cowles (2007)