Bispira
brunnea
a brown morph photographed in the Bahamas.
One
of my favorite things to show someone new to the marine
environment is the beautiful crown of a feather duster worm. This
"flower,” I explain, is the crown of a worm that lives in a
tube, and it is both a feeding apparatus and a breathing gill.
Next I ask the observer to slowly try to touch the crown. The
instant disappearance of it as the worm reflexively withdraws into
its tube always leaves a great impression!
I
can observe numerous varieties of these creatures along the shore
of Biscayne Bay here in Miami, and I have also kept many varieties
of them in my reef aquariums. Some of them reproduce, some thrive,
others are more delicate and just survive for extended periods of
up to two years. This article covers the genera most often seen in
aquaria.
The
structure of the crown
The
crown of feather duster worms is composed of a series of
feather-shaped rays called radioles. The radioles are arranged in
two half circles that form a funnel shape in many species. In some
they form a horseshoe shape or one or two spirals. Cilia on the
radioles generate currents that draw water upward into and out of
the crown, and they also move particles trapped on the radioles
into a groove that conducts the food particles down to the base of
the radiole where they are sorted. More on that in a moment.
Water
movement
While
some species are capable of living in quiet waters (for example,
behind live rock) because of the effective pumping by the cilia,
in most species the movement of water through the crown is
assisted by water currents in the environment. These species occur
only where they typically receive moderately strong laminar water
currents. Others, such as the Serpulids withchristmas-tree-shaped crowns, tolerate turbulent and
multidirectional flows and waves, in addition to laminar currents.
Feeding
The
sorting of trapped particles in the crown begins in the conducting
grooves on the radioles and finishes at the base of the crown.
Large particles ride high on the conducting grooves and they are
rejected and emitted up into the current stream at the base.
Medium sized particles pass along the center of the conducting
grooves and are moved to storage areas where they are subsequently
used in the construction of the tube in soft tube species. Fine
particles are moved by cilia along the lower portion of the
conducting groove into tracts that lead into the mouth. The food
includes bacteria, fine detritus and other particulate organic
matter, phytoplankton, and tiny microorganisms
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Taxonomy
Feather
duster worms are members of the Phylum annelida, the segmented worms,
which includes the common earthworm. The feather dusters belong to the
class Polychaeta, one of the four classes of annelids. The Polychaetes
(literally "many hairs") have segmented bodies, and each
segment bears two or more appendages called parapodia. The appendages
are often hair-like, hence the name bristle worms for many varieties of
polychaets. In feather duster worms the hair-like chaetae are much
reduced. The feather duster worms belong to several families and
subfamilies of Polychaeta. Those with soft tubes consisting of a
polysaccharide matrix and trapped detritus are in the family Sabellidae,
which has only one genus with an exceptional calcareous tube. Most
"hard-tube" feather dusters belong to the family Serpulidae,
and many members of this family have an operculum that is formed from a
modified radiole in their crown. The operculum is a "trap
door" that shuts the entrance to the tube when the worm withdraws.
The ornamentation of the operculum is used for identification of some
species.
This
species of Salmacis photographed under a ledge in
the Solomon Islands has tiny white branchial crowns.
Other Species have red crowns, like most Filogranella
spp.
Reproduction
Feather
duster worms reproduce both sexually and asexually. Sexual
reproduction involves the release of gametes into the water
where the fertilized eggs develop into free-swimming larvae that
eventually settle in an appropriate habitat. In the case of
Serpulids, they settle on corals and the coral grows around the
calcareous tube they build, making asexual reproduction nearly
an impossibility for them. Soft tube varieties reproduce
sexually, but many form dense colonies of clones by a budding
process called scissipary. In this process the posterior end of
the worm breaks off and develops a new crown while the
"parent" grows a new posterior.
Shedding
the crown
Many
varieties of feather dusters periodically shed their crown,
leaving the novice aquarist horrified and believing the precious
creature has died. Don't remove the tube! The feather duster
will re-grow its crown in a matter of weeks. Sometimes shedding
of the crown is an indication of starvation or that something
about the environment is irritating. If the occurrence is
infrequent, it is nothing to worry about. If it occurs every
couple of months, there may be an aggravating factor.
Escaping
the tube
Sometimes
Sabellastarte spp. leave their tube. This exposes the worm, making it
vulnerable to predators. In general it is best not to try to re-insert
the worm into its tube. One is more likely to injure it this way, and it
is likely that it left the tube for a good reason. Usually they move
this way to a better position, in a stronger current. The worm can build
a new transparent tube in a matter of hours, and it will coat the tube
with sand and detritus over a matter of a few days.
Following
is a review of the common varieties that are kept in aquaria, noting
important husbandry considerations and comments regarding hardiness.
Bispira
The
genus Bispira contains some
common and popular species imported for the aquarium trade, and it also
contains some species that reproduce prolifically in aquaria, being
introduced with live rock. Not all Bispira
spp. reproduce prolifically, however, and one species, the common
"cluster duster," Bispirabrunnea, rarely survives in aquaria. With a little trick, however,
one can change its captive fate, as I'll shortly explain.
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Bispira
viola
is the most common species in aquaria. It seems to be ubiquitous-
by definition it can be found in most reef aquariums around the
world. It is possible that many species exist with essentially the
same appearance, but it is equally possible that a single prolific
species is widespread in both temperate and tropical oceans. Bispira
variegata from the Caribbean has essentially the same
appearance, but it grows larger and tends to burrow in sand while B.
viola is common up high on rocks and on algae. Bispira
tricyclia is superficially identical to B.
variegata, and lives in the same habitat, but in the
Indo-Pacific region. Both are occasionally harvested for
aquariums, and they are long-lived. They reproduce in aquariums by
fission, but much more slowly than B.
viola. Bispira guinensis is one of my favorite species. It forms a spiral
crown when fully developed. Newly formed crowns are funnel shaped
and essentially identical in appearance to Bispira
tricyclia and B.
variegata.
Bispira
brunnea,
the cluster duster, superficially resembles other member of this genus,
but it has a habit so different that I personally believe it should be
placed in a separate genus. It forms clusters of clones attached to a
hard substrate at a central point. The tubes do not migrate and
proliferate onto adjacent substrate like other members of the genus, but
develop parallel to one another forming a larger ball of straight tubes.
Asexual reproduction thus does not spread the species; it simply
increases the colony size. This species is harvested for aquariums from
Haiti and the Dominican republic. It is extremely common throughout the
Caribbean, including the Bahamas, but mysteriously does not occur in
Florida. The harvested specimens have been removed from the rock,
something easy to do since they are loosely attached. They do not
readily reattach to rocks when placed in the aquarium, and it is for
this reason that they usually perish with a few weeks or months. I have
solved this problem with a neat trick. The cyanoacrylate gels now
popularly used to attach stony coral fragments to rock can likewise be
used to attach Bispira brunnea
to rock. I show a photograph demonstrating a colony attached to glass
this way. After taking the photograph for demonstration purposes I moved
the colony and attached it to a rock. The rigid bonds of cyanoacrylate
do not adhere permanently to glass because glass is a special form of
liquid (even though it is hard) with molecules in constant motion that
break the rigid bonds. Attached B.brunnea appear to be
long-lived in aquaria, provided they are given a moderate current and
weekly additions of foods such as live or spray dried phytoplankton.
They also feed on bacteria and plankton generated within the tank, so
one does not need to offer supplemental food every day.
Branchiomma
cf. curtum
This
tiny species was first described in aquarium literature by Fossa and
Nilsen (2000). It is a common inhabitant of reef aquariums that is
introduced with live rock, live corals, algae, or other substrates. It
reproduces prolifically in sumps, refugia, and all over live rock and
among algae. Aquarists who first see this species often mistake it for
small Sabellastarte, because
it has a similarly patterned crown. Reports of mass reproduction of Sabellastarte
in aquariums are generally due to misidentification of Branchiomma.
Sabellastarte
The
ever-popular giant feather dusters imported from Puerto Rico, Haiti,
Hawaii and Indonesia belong to the genus Sabellastarte.
The color of the crown is variable, and includes shades of brown, white,orange, and maroon. Sabellastarte spp. can be long-lived in aquaria, but often they
"last" for several months only. It is a commonplace occurrence
for them to occasionally shed their crown, for reasons not well known.
They readily re-grow the crown within a few weeks or months. When fed
liquid invertebrate foods and phytoplankton frequently, they can live
for several years in captivity.
Notaulax
Notaulax
spp. are rarely harvested directly, being introduced to aquariums with
live rock. They have a soft brown parchment-like tube and occur imbedded
in the rock. Their crowns can be cryptic, but some varieties are
brightly colored. The yellow Notaulax
occidentalis found on reefs in Florida and the Caribbean are among
my favorite feather dusters. They look like eyelashes that can suddenly
"blink" out of sight. They do not reproduce in captivity, but
they are very long lived- thriving for many years.
Protula
bispiralis
The
Hard tube "Coco worm" from Indonesia is a popular and
expensive creature that is not recommended for the beginner. Its life
span is not very long in captivity, usually not more than two years, and
often much less than that. It has not been reported to reproduce in
captivity. One should provide sufficient calcium and alkalinity for it
to build its calcareous tube, and plenty of food, such as liquid
invertebrate foods, live phytoplankton, or spray-dried phytoplankton.
Christmas
Tree worms
The
Christmas tree worms belong to the genus Spirobranchus. They are
typicaly found imbedded in the skeletons of living scleractinian corals
or in fire corals (Milepora
spp.). The sight of a large colony of them in a head of Porites
(their most common "host") is a treasure common to coral reefs
around the world. Each crown has a different color pattern, so the look
is like a bed of wildflowers or a pansy patch. Christmas tree worms are
occasionally imported for aquariums from Indonesia. They can survive if
their host coral dies, but they may have to compete with algae if it
grows on the coral skeleton, something they cannot do. They appear to
gain some nutrition from their host's mucus as well, and so it is
generally believed that long term survival of Spirobranchus
spp. requires that the coral host be maintained in a healthy growing
condition. Novice aquarists often fail to recognize that maintaining the
coral requires sufficient light intensity, water movement, calcium and
alkalinity levels, and low phosphate levels. The small Porites
colonies harvested for aquaria are from shallow, brightly illuminated
zones with strong currents. Feeding is important for Spirobranchus
spp. Offer plenty of food, such as liquid invertebrate foods, live
phytoplankton, or spray-dried phytoplankton. Strong currents assist them
in gathering the food.
Filogranella
and Salmacis, and Vermiliopsis
Members
of these genera form small calcareous tubes and have red or white
crowns. They reproduce in aquaria, and can be found on and inside pumps
and plumbing, as well as on the undersides of live rock or on the walls
of the aquarium or sump. Thick colonies of them sometimes occur on
reefs, and they are occasionally harvested from the Caribbean.
The
"Coco Worm" or "Hard tube duster," Protula
bispiralis is a popular and expensive species occasionally
harvested for aquariums. With care it can survive for a couple
of years, but it often has a shorter lifespan in captivity.
Bispira
cf.
tricyclia photographed in the Solomon Islands. Dense
colonies develop in fine sand in quiet places on the reef, often
under ledges.
This
photo demonstrates the use of Cyanoacrylate gel glue to attach Bispira
brunnea. See text.
These
Spirobranchus spp. photographed in the Solomon Islands
are in their preferred host coral, Porites.
Bispira
brunnea
a purple morph photographed in the Bahamas.
Bispira
viola
may reproduce prolifically in reef aquariums. Its ability to
trap detritus, used to build the tubes, serves a useful function
in aquariums, and can help to limit the growth of algae that
trap and use detritus.
Branchiomma
cf. curtum reproduces prolifically in aquariums, often
leading to the mistaken impression that it is the offspring of
much larger Sabellastarte.
Filogranella
sp. from the Bahamas. These form calcareous tubes and survive
and reproduce in aquariums. They should be maintained in the
shade to prevent algae from smothering them, and they prefer
moderate laminar water flow.
This
unidentified feather duster with a 3 inch diameter crown is
common on reefs in Southern Japan. It has a soft tube
imbedded in rock like Notaulax spp.
The
same species of feather duster in Japan has a variety of color
morphs. It is popular with aquarists there.
Notaulax
occidentalis
look like yellow false eyelashes under ledges on reefs in
Florida and the Caribbean. Their tube is imbedded in rock so,
unfortunately, they cannot be harvested without rock.
Closeup
photo of Pileolaria sp. reveals a coiled tube reminiscent
of the shell of a Nautilus.
This
tiny feather duster with a calcareous tube commonly reproduces
sexually in aquariums, settling all over the glass, rocks,
pipes, and pumps. It is a Pileolaria sp.
The
classic shape of a feather duster crown, with pinnate radioles.
This is a Sabellastarte sp. photographed in the Solomon
Islands.
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Predators
It is
important to consider leaving out potential predators of feather
duster worms when designing an aquarium to house them.
Butterflyfishes quickly decimate them as the feather duster crown
is a delicacy they really appreciate for dinner, lunch, and
breakfast, while the worm left in the tube is finished for desert.
Crabs of many kinds find great pleasure first in making the crown
withdraw, then pinching the tube, squeezing the life out of the
worm and finishing it off in a single session. Some (but not all)
wrasses will make short work of feather dusters, eating them so
quickly that the worm probably hardly realizes it is no longer
safely in its tube. Some hawkfishes likewise will eat them.
Serpent stars are generally safe, but they may pick apart a colony
of Bispira brunnea,
especially when the colony is first introduced to the aquarium and
it smells like your fish-food flavored finger tips.
References
Barnes,
R. D. 1980. Invertebrate Zoology. Saunders College, Philadelphia.
Fossa
S. and A. Nilsen. 2000. The
Modern Coral Reef Aquarium. Vol 3. Birgit Schmettkamp Verlag.
Humann,
P. 1994. Reef Creatures.
New World Publications, Inc.
Sprung,
J. 2001. Invertebrates: A
Quick Reference Guide. Ricordea Publishing.
