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Worms - Phyla Annelida, Nemertea, Platyhelminthes (Flatworms)
Text and Photos by Jim Young

Annelids (Polychaetes)
Nereis latescens
Nereis Worm
Oregon to Mexico (estimated)
Family Nereididae

Dense populations of this small polychaete worm were found residing in the mud flats at the south end of Netarts Bay in numbers of hundreds per square meter.  Generally, less than two inches long, it best fit keys for Nereis latescens, although this is not certain.  Further attempts at verification will continue. 

The genus Nereis and its close family relatives are among the most common polychaetes along the Northwest Pacific shoreline.  They are characterized by two palps on the prostomium and four pairs of tentacular cirri arising from the anterolateral corners of peristomium.  There are usually two pairs of eyes and an eversible proboscis bearing two fang-like, often serrated, jaws.  They are predators and scavengers.   Large species of Nereis are commonly use in teaching laboratories and are collected for fish bait. 

Nereis holes
Nereis vexillosa
Mussel Worm
Alaska to California
Family Nereididae

Also called the Banner Sea-Nymph because of it long and large strap-like notopodial (dorsal) lobes on its posterior parapodia that it waves like banners, it is found in beds of California Mussels (Mytilus californianus), hiding among the byssal threads.  It is often collected for fish bait by anglers.  It may grow up to six inches (15 cm) long, and is colored a dark gray to brown with tones of iridescent green, blue, and red.  It has an extendable proboscis equipped with a pair of serrated jaws it uses to clip off pieces of algae for food.  It reproduces by the nereid brand of epitoky, where the worm transforms into a heteronereid that has posterior body parts
swollen with gametes.  When conditions are right, usually winter and spring, the males swarm first followed by the females whose body wall ruptures to release the eggs which are then fertilized by the spawned sperm.  Afterwards, both males and females die.

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Alitta brandti/Alitta virens 
Giant Piling Sea-Nymph/Clam Worm
Alaska to California
Family Nereididae

These two nereids, which used to be in the genera Nereis and Neanthes, are often grouped together in identification keys because they are difficult to separate morphologically, and they occupy similar habitats and ranges.  They are large, up to more than four feet long (1.5 meters), live in sand and mud flats, have massive jaws used for defense that can produce a painful bite when handled, but feed mostly on algae.  The upper lobe (notopodial lobe) of their posterior parapodia is large and paddle-like, distinguishing them from the similar but slightly smaller N. vexillosa, the mussel worm, which has a long strap-like upper lobe.  These worms, like other nereids, reproduce by a phenomenon called epitoky, the production of a sexually reproductive worm from an asexual individual.  This sexual "epitoke" or heteronereid is filled with gametes, its parapodia enlarge enabling it to swim, and it enters a swarm with other heteronereids where they all spawn together, ensuring fertilization.  This swarming is linked to phases of the moon and usually occurs during summer nights.
Alitta succinea
Common Clam Worm
Washington to California
Family Nereididae

This specimen was found on outer shore rocks at Oceanside, associated with a sea cabbage (Saccharina sessilis) holdfast.   Alitta succina ranges world-wide in both temperate and tropical waters but is not native to the Pacific coast of North America.  It is native to the Atlantic coast and was possibly introduced here and elsewhere through ballast water released from ships, fouled hulls, or by natural dispersion.  It is now common on our shores.   It lives in a variety of intertidal and subtidal habitats, in and out of sand and mud bottoms, in rocky areas, eelgrass beds, and among mussels and oysters.  It is euryhaline, living happily in both hyper- and hyposaline conditions.  It can survive a reported temperature range of 12-35 degrees Celsius. 

It is an opportunist feeder, digesting micro-organisms on ingested sand grains, clipping off chunks of algae with its two jaws, and capturing small invertebrates. 

Reproduction, as in other nereids, is by epitoky where the worms metamorphose into heteronereids (the epitoke stage), swim to the surface, spawn in masse, then die.  Metamorphosis and swarming can be stimulated by temperature changes in association with phases of the moon.

Alitta succinea, in the past, was called both Neanthes succinea and Nereis succinea.
Nephtys caecoides/ Nephtys californiensis
Sand Worm/Redlined Worm
Alaska to South America
Family Nephtyidae

While treading across the sandy flats of Netarts Bay, you will see many small holes often surrounded by small mounds of sediment that are made by a host of segmented worms.  Some may be the burrows of the polychaete worm Nephtys caecoides, or the sand worm.  It is a carnivorous predator that resembles a nereid but has an anterior end that is entirely different.  Its antennae (tentacular cirri) are short, not long like those on Nereis.  Its proboscis, short and wide, bears a variety of papillae rather than the jaws of nereids.  If you pick it up then replace it on the sand, it will immediately begin to burrow.

A related species Nephtys californiensis occurs on the sandy beaches of the open coast such as that between Netarts and Oceanside.

Pista pacifica  
Fringed-Hood Spaghetti-Worm
British Columbia to California
Family Tereibellidae. 

Sticking out of the sand and mud flats you may find a strange-looking tube with a bent, fringed, triangular hood covering the opening.  It contains a tentacled polychaete, Pista pacifica, in the family Tereibellidae.  The tube is composed of sand and mucous and extends vertically into the sediment to about 80 centimeters.  The worm itself is about 30 centimeters long and can move up the tube to feed or down to protect itself from predators.  It will invert itself when it has to defecate so its anus is at the tube opening, allowing the feces to wash away.  The body of the worm is soft, fragile, and bright red, the color due to oxygen-carrying hemoglobin.  It feeds by capturing detritus with its tentacles which it carries to the mouth, and its hood is oriented about 90 degrees to the prevailing current, which allows more exposure to passing detritus.  Another polychaete, the scale worm Halosydna brevisetosa, often lives its tube. 
Olive snail.
At low tide across some sand flats in Netarts Bay you may encounter meandering and crisscrossing trails of the beautiful little purple olive snail.
Click here for more information!

Worm extracted from tube.
Arctonoe fragillis
Fragile Ruffled Scale Worm
Alaska to California
Family Polynoidae

  Fragile Ruffled Scale Worm is commensal with its most common host Evasterias troschelii, the Mottled Sea Star, although it may live with other sea stars or be free living.  It resides mostly in the ambulacral grooves on the underside of the sea star's arms.  It's scales, called elytra, are fragile and will easily dislodge, hence the specific name fragillis.  The elytra have a frilled edge and their point of attachment to the body is often white. 

The term commensal means that in a close association between the two organisms, one member derives benefit from the relationship but offers no disadvantage or advantage to the other member.   This has been thought to be the case with Arctonoe, where the sea star host gains nothing.   There is evidence, however, that points to a truly mutualistic relationship between Arctonoe and its partner, a relationship where each benefits.  The worm is attracted to the host by its "smell", that is it is chemically attracted, where it feeds on detritus that settles on the sea star.   It has also been shown that the sea star is chemically attracted to the scale worm and will consistently choose the worm over food (Wagner et. al., 1979).  The advantage may be cleaning of the sea star surface.

Halosydna brevisetosa
Eighteen Scale Worm
Alaska to Mexico
Family Polynoidae

Halosydna brevisetosa can be free living under rocks, on pilings, and in mussel beds.   This specimen was found on outer shore rocks associated with sea cabbage holdfast. It can also live commensally with other invertebrates including moon snails, hermit crabs, and tubeworms, especially the tube dwelling terebellids, apparently not by chemical attraction but more likely by water currents created by the host or just by a tactile connection.  It’s a polynoid, one of the scale worms that have paired scales called elytra on their dorsal sides, in this case eighteen pairs of elytra.  Free living individuals can reach three inches (8 cm), commensal ones up to four inches (11 cm).  It is a predator feeding on other worms, but also sharing food with its host when commensal.  It reproduces during summer.
Olive snail.
At low tide across some sand flats in Netarts Bay you may encounter meandering and crisscrossing trails of the beautiful little purple olive snail.
Click here for more information!
Serpula columbiana
Red Trumpet Calcareous Worm
Alaska to California
Family Serpulidae

Serpula columbiana is common in the lower intertidal and subtidal zones in rocky environments, though it is also found attached to pilings, docks, and floats.  It lives in a serpentine calcareous tube that is attached to a substrate full length except the open end which is curved outward.  The tube is secreted by two calcium sacs near the posterior end of the peristomium, the worm’s second anterior segment.  Its anterior end displays an array of feather-like gills that can be drawn quickly inside the tube and sealed with a funnel-shaped operculum when the worm is disturbed.  The gills and operculum are bright red.  It has two eyes on the peristomium, but none on the gills.  Along with a closely related family, the Sabelliidae, the Serpulidae contain the blood pigment chlorocruorin which is green when oxygenated but dark reddish brown when deoxygenated.  It is a filter feeder, using its extended gills to capture detritus and small organisms.  The gills, also called radioles, are lined with cilia that convey food to the mouth.  Look for on the rocks at Oceanside, especially in protected hollows.

In older books this worm was called Serpula vermicularis, but that name is reserved for similar worms on the Atlantic coast.
Olive snail.
At low tide across some sand flats in Netarts Bay you may encounter meandering and crisscrossing trails of the beautiful little purple olive snail.
Click here for more information!

Eudistylia vancouveri
Vancouver Feather-Duster Worm
Alaska to California
Family Sabellidae

This feather-duster worm lives in a rubbery, parchment-like tube that is attached to rocks, pilings, or even muddy bottoms.  You can find a few of these tube worms tucked into crevices in the outer rocks of Tunnel Beach.  The tube is tough, flexible and ideally suited to rough, wave-swept environments as well as the more benign waters of bays with good circulation.  Its gills, also called radioles, crown its anterior end and extend from its protective tube in a blaze of alternating red and green bands of color, making the worm one of the more beautiful invertebrates on our coast.  When disturbed, the gills, with the help of giant nerve fibers that run through the body, will zip back down the tube in a split second, frustrating any fish or crab looking for an easy bite for lunch.  It even has light-sensitive eye spots on the gills that can detect shadows cast by an oncoming predator.  This is a suspension feeder, and its gills serve a dual purpose, breathing and eating.  More on this in a bit.

These worms are large and muscular, up to a foot (30 cm) long and as big around as your finger.  Their tubes are even longer.  They usually live in clusters, sometimes in the hundreds, the bases of their tubes tightly intertwined.  Their blood contains the respiratory pigment chlorcruorin which is bright green when oxygenated, a deep metallic red-brown when unoxygenated.  They live in depths from low intertidal to subtidal.

As odd as it seems, I have a special relationship with this worm.  In the late 1970s and early 80s, when I was a research scientist working on the bioavailability and effects of heavy metals on marine organisms, E. vancouveri was my main test subject.  It turns out that its gills, those feather-like radioles sticking out from the end of its tube, were sensitive to copper, became necrotic, and began to disintegrate at very low levels of the metal (<10 ppb) in seawater.  It also turned out that the animal gradually, within a couple of weeks, was able to develop a protein that bound up the copper and detoxified it, allowing the gills to regenerate even though the worm was still being exposed to toxic levels of the metal.  As part of my research, I studied the gill’s microscopic structure, both before and after exposure to copper.  My bioavailability and toxicity results were published long ago, but much of the microscopic structure (ultrastructure) of the normal gills was not.  So, I present a summary of it here.

Each radiole consist of a shaft that I called the rachis, like the central shaft of a feather, with pinnules branching out at a 40 to 50-degree angle, curving away from the rachis in a pinnate arrangement.  Each pinnule has a frontal side with a food grove ciliated with both long and short cilia, and an abfrontal side with a narrow row of cilia along its rounded edge (see blue diagram) that stretches from the base of the pinnule to its tip.  Looking at the pinnule in cross section and working inward, there is an outer glandular epidermis, followed by a layer of inner fibrous connective tissue and longitudinal muscular layers that surround a lumen (a fluid-filled space) and a row of supportive cellular cartilage that extends the length of the pinnule and expands into the rachis.  The lumen contains a nerve chord and a single blind-ending branchial blood vessel which is branched from the rachis.  The blood flow is unusual in that there are no afferent and efferent vessels to circulate blood, only the single vessel through which blood sloshes back and forth. 

The epithelium has a microvillous surface and gland cells that secrete mucus-like substances to the outside of the pinnule that serve perhaps as a lubricant or a deterrent to predators, but also may help in conveying food along the food groove to the mouth.  The epithelium also contains the pigment granules that color the radioles.  Two types of cilia line the food groove, long ones that appear to be bundled in groups or ordered rows along the outer edges (the laterofrontal cilia) and short ones in the center of the groove.  The abfrontal cilia and the long cilia create currents that bring suspended food particles up between the pinnules where they can be directed into the frontal food groove.   Once particles enter the groove they are sorted into three size grades by both the short cilia and the shape of the groove which has a ridge on each side part way into its narrowing depth that runs the length of the pinnule.  The smallest particles can get past the ridge and go to the bottom of the groove to become food.  The medium ones, blocked by the ridge, are carried by the cilia to a ventral sack to be used in tube formation.  The largest particles are rejected by the palps.

This type of feeding, first described by Nicol in 1931, is typical of other sabellids and is featured in most of today’s invertebrate zoology textbooks.

Nicol, E. (1931). XXIII.-The Feeding Mechanism, Formation of the Tube, and Physiology of Digestion in Sabella pavonina. Transactions of the Royal Society of Edinburgh, 56(3), 537-598. doi:10.1017/S0080456800016495

Worms at Tunnel Beach retracted into their tubes.

1.  Single radiole with rachis (near bottom) supporting pinnules.

2.  Scanning electron micrograph (SEM) of pinnules.

3.  SEM of frontal food groove with long (fronterolateral) cilia and short groove cilia.

4.  Diagram of pinnule cross section.

5.  Diagram of food sorting mechanism in food groove.

6.  Transmission electron micrograph (TEM) of epithelial gland cell.

7.  Longitudinal TEM micrograph of pinnule showing glandular epithelium and cellular cartilage.

8.  TEM of non-glanular epithelium.  Dark bodies are pigment granules.

9.  TEM of cellular cartilage and chondrocyte, the cell that forms the cartilage.

10.  Oblique TEM of frontal food groove.

11.  TEM of grouped fronterolateral cilia.

Abarenicola pacifica
Pacific Neapolitan Lugworm
Alaska to California
Family Arenicolidae

Present in some of the more sandy and silty tidal flats, especially near the edges of southern end of Netarts Bay, is the Pacific Neapolitan Lugworm, easily recognized by its pile of coiled fecal castings.  It lives in a U- or J-shaped sand tube, head down, selectively feeding on organic matter and small organisms such as nematodes and protozoans by ingesting sand, organics, and organisms pumped through the tube.  It deposits its undigested material at the tube opening.  You may see the opening in the center of the fecal pile.  It has up to thirteen branched gills that are notopodial (dorsal part of the parapodia), filled with hemoglobin, and bright red.  The individuals photographed here are small, little more than an inch (3 cm), but the species can grow to over 5 inches (15 cm).

Coiled fecal pile.

Dodecaceria fewkesi
Pacific Fission Worm
British Columbia to California
Family Cirratulidae

While wandering our local beaches after a winter storm, you may find what looks like a piece of coral, a chalky white lump of rounded "rock" that is riddled with tiny holes and channels.  It is neither coral or rock but is a piece of a wave-weathered-home of a colony of the Pacific Fission Worms Dodecaceria fewkesi that has washed ashore.   You can see a small living colony attached to the side a rock outcrop in the lower intertidal zone on Tunnel Beach.  This worm secretes a calcium carbonate tube that is fused to adjacent tubes.  The colony begins with a single worm, the "founding father" which divides in half.  The daughter worms, when they mature, also divide in half, and their daughters divide, and so on, and the colony continues to grow, sometimes forming huge stony masses, especially on the open rocky coast. 

The larger colonies are mostly subtidal, and what you find on the beach are parts of colonies that have been dislodged by storms then rounded by the surf.  Some storm deposited chunks of "rock" may contain live worms, some not.  Dodecaceria feeds by capturing phytoplankton with two grooved palps that extend from the tube.

Photo from internet.

Owenia collaris (maybe)
Tube worm, Bamboo worm
Family Oweniidae (maybe)

I list this small polychaete worm because it is common in the nearshore sandflats along the east side of Netarts Bay.  Look for it in patches a few yards south of the kiosk on Netarts Bay road, about 20 to 200 feet from the base of the riprap.  Thin, fragile and no more than an inch long and a millimeter wide, it lives in sand tubes, tubes formed from sand grains cemented together in a mucus matrix, that stick above sediment surface.  You can see the worm itself by collecting the tubes and dissecting it out.

It seems to be a member of the Owenidae, and the 1976 Stout Report* includes O. collaris as occurring in Netarts Bay, but I may have misidentified it.  It does not appear to have a strong tentacular crown on its anterior end as illustrated by Hartman 1969, p493*, although the tentacles may have been retracted or folded and are not distinct.  It could be Galathowenia oculate, previously called Myriochele oculata.  Or, there is also a chance that I have completely misidentified this worm, and it may belong to the family Maldaniidae, the bamboo worms, such as Axiothella rubrocincta.  One indication of this is that the setae near the anterior end have more than two teeth.

If anyone has knowledge of this inscrutable worm, please let us know.

* See references.

Notomastus tenuis
Thread Sludgeworm
Alaska to California
Family Capitellidae

When digging for Butter or Gaper clams on Netarts Bay, you will almost always run into these bright red incredibly long thin polychaetes Notomastus tenuis.  They are common, gregarious, and live in sandy and silty mud.  To extract one whole is difficult.  You usually come out with pieces.  It may be up to 12 inches (30 centimeters) long and a millimeter thick.  It ingests sediments, digesting anything nutritious, and expels the remainder as small casting on the surface.  It has very small parapodia, hooked setae, and no tentacles.

Syllis elongata (maybe)
No Common Name
British Columbia to Mexico
Family Syllidae

This tiny syllid worm, about five-eighths of an inch long (15 mm) and 1 mm wide, was found crawling among the branches of the holdfast of sea cabbage Saccharina sessilis.  It’s a very common worm in brown algae holdfasts on rocky shores, but so are some other syllids.  The syllids are a complex group, but you can distinguish them from other polychaetes because they have a barrel-shaped muscular region in the anterior part of their digestive tract called a proventricle, a crop-like organ that can be seen through the body wall.  This syllid is in the subfamily Syllinae, members of which feed on the internal fluids of a several invertebrates.
  Many syllids reproduce by epigamy, some brooding their eggs, some not.  Others reproduce by schizogamy, producing sexual stolons filled with gametes that bud off from adult males and females.  

Scoletoma zonata
Iridescent Zone Worm
Alaska to Mexico
Family Lumbrineridae

Also called Lumbrinereis zonata, this polychaete is common in the cobbled/sandy substrate near the mouth of Netarts Bay, just south of Happy Camp where gaper clams are commonly dug.  It is a long worm, more than six inches, has conical, unadorned prostomium (the first segment) with no eyes or appendages, simple hooked and hooded setae, and a creamy light brown to pinkish color with a subtle iridescence.  It can also occur in mussel beds and in seaweed holdfasts.

Eupolymnia crescentris
Spaghetti worm
Alaska to Mexico
Family Terebellidae

Assemblages of this burrowing and tube-dwelling polychaetes can be found at low tide, just south of the clamming kiosk out near the eastern edge of the channel.  You will see numerous tube ends sticking up about and inch above the sediment, the buried part of the tube extending downward several inches into the sediment.  The worm is olive green with tentacles around the mouth and three pairs of reddish, highly branched branchia. The tentacles are used for gathering food, usually at night.  The greenish color is
due to granules of green pigment deposited in the coelomic cells and in the epidermis.  The common name is more appropriate to other species of Eupolymnia that have much longer, spaghetti-like feeding tentacles.

Eupolymnia heterobranchia is considered a synonym by the World Register of Marine Species (WoRMS).

Paranemertes peregrina
Purple Ribbon Worm, The Wanderer
Alaska to Mexico
Family Emplectonemeratidae

The Mud Nemertean, Paranemertes peregrina, lives in burrows among the bristle worms, Nereis spp., along the very edges of Netarts Bay.  It is an unsegmented ribbon worm (phylum Nemertea), up to a couple of inches long, and dark brown or purple on its dorsal side and a light tan underneath.  It is a formidable predator, feeding on its neighboring Nereis.  It crawls from its burrow just after the tide recedes, follows a trail of mucous left by Nereis, and upon contact with its prey, everts its proboscis that is armed with a poison-injecting stylet, stabs and paralyzes the worm, then eats it by swallowing it whole.  The poison is the neurotoxin, tetrodotoxin, the same toxin found in rough-skinned newts, puffer fish, and the blue-ringed octopus

Cerebratulus sp.
Ribbon Worm
Alaska to California.
Family Lineidae

This nemertean, possibly C. marginatus, is in the sandy and muddy sediments of Netarts Bay.  It is pale yellow or creamy white.  It is a member of the Order Heteronemertea which have an unarmed proboscis and a mouth that is below and behind the brain. It has deep cephalic slits.

It has unusual early life stages.  Its free-swimming larva, called a pilidium, develops a series of epidermal invaginations called imaginal discs.  These discs grow around the larval gut and, in time, become the juvenile worm.  Then the juvenile suddenly breaks out of the larva and often devours it as its first meal.  Visit https://bocasarts.weebly.com/nemertean-tools.html for more information.

Cephalic Slit

Cephalic Slit

Malacobdella siliquae 
The Razor Clam Ribbon Worm
British Columbia to Oregon
Family Malacobdellidae

This odd-looking worm, which may be mistaken for a parasitic fluke, is a nemertean, one of the ribbon worms, and it is only found in the mantle chamber of the Razor Clam Siliqua patula, attached to the chamber wall, usually near the base of the incurrent siphon, by a posterior sucker.  It feeds on small organisms and detritus sucked in by the clam as it feeds and breathes.  It was previously grouped with Malacobdella grossa, which inhabits several other bivalves and is more widespread, but was split off by Eugene Kosloff in 1991 and given the current specific name.  Another ribbon worm described by Kozloff (1991) is M.macomae which is hosted by Rexithaerus (Macoma) secta and Macoma nasuta.

The wavy structure in the figure is the gut, which is devoid of the diverticula found in other nemerteans.  The round bodies are probably gonads, and the sucker is to the left.  If you inadvertently eat this worm with a Razor Clam, it won’t hurt you.
Preserved specimen showing sucker at the left end
Live specimen

Amphiporus sp.
Many-Eyed Ribbon Worm
British Columbia to California
Family Amphiporidae

About a half-dozen of these tiny creamy-white nemerteans were found on outer shore rocks at Oceanside, nestled in sea cabbage (Saccharina sessilis) holdfasts.  There are several west coast species of Amphiporus, and these individuals were possibly A. cruentatus or A. imparisposus, both of which can be found in holdfasts.  The worm has many eyes, those black spots pictured here on the head of the worm, and the arrangement is like those of A. imparisporus.  Each worm that I found was about an inch and a half long (4 cm) when stretched out and less than 1 mm thick.  It is a carnivore with a single pointed stylet, probably venomous, on the end of the proboscis used to capture prey, and often feeds on barnacles and amphipods.

Platyhelminthes - Polyclad Flatworms
Polycladida (possibly Notocomplana acticola)
Polyclad Flatworms
Family Notoplanidae

Platyhelminthes is the phylum of flatworms that includes everything from free-living Turbellarians to parasitic flukes and tapeworms.  Most of those that are free-living are aquatic, including the small brownish, cross-eyed planarians we studied in high school biology.  The polyclads, which are marine, are in the order Polycladida, a hugely diverse and a worldwide but difficult group.  Often, outside of some that are spectacularly colored, they hard to identify, and there are many difficult species of polyclads along the Pacific coast.  Identification generally depends on internal anatomy, which means producing thin sections of the worms for microscopic examination.

That said, this common polyclad may be in the genus Notocomplana (=Notoplana).  It can be found under rocks, in mussel beds, in and around seaweed holdfasts.  This one was in a mussel bed.  Polyclads glide along a surface almost amoebic-like, adjusting their shapes to the topography.  They are carnivorous, feeding on molluscs, crustaceans, worms, or what ever invertebrates they can find.  The mouth is located centrally on the ventral side, and they have a folded pharynx that can be protruded through the mouth and extended over the prey where digestion begins.  Digested food is brought back through the mouth into and extensively branched gut.  Some polyclads have many eyes along their margins, some have eyes clustered anteriorly, as does this specimen.

Eye clusters

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