Subject: Pectinatella magnifica
Date: Thu, 14 Aug 1997 18:54:12 -0500 (EST)
I was in Massachusetts
in 1977 (coincidentally, I was
attending the International Bryozoology Association
conference held at Woods Hole) and, in the course of some of
our explorations, we came across a pond containing a number
of large colonies of P. magnifica, much as you describe - so
this is certainly not a new phenomenon in Massachusetts.
It may be that
in some years colonies of this species are
relatively small or few and far between - but in other
years, for unknown reasons (perhaps a good food supply,
perhaps relatively little disturbance) there is a build-up
of many large colonies (and they can, under optimum
circumstances, get as large as a bushel basket!). Most of
the mass is a secreted gelatinous material; the actual
living colony is fairly close to the surface, and this is
also where you find the statoblasts. A number of other
organisms (particularly nematodes, insect larvae etc.) may
burrow into the gelatinous mass. It is possible that the
living colony (which consists of relatively small feeding
zooids) will die off, leaving the gelatinous mass with
statoblasts (the gelatinous mass disintegrates within a few
For what it is
worth, I believe that the so-called
freshwater "bryozoans" or phylactolaemates are not really
bryozoans at all, but are freshwater phoronids, and the
statoblasts (which you have described) are derived from the
so-called "fat body" of phoronids. Most of my work on these
organisms has been on their chromosomes (the chromosome
number for P. magnifica is 18).
are for reproduction; each statoblast is
capable of producing a new massive colony. Since
statoblasts are produced asexually, each of these new
colonies will be genetically identical to the parent colony.
The statoblasts produced at this time of year will probably
not germinate, however, until next spring.
magnifica can be a nuisance, as the large
gelatinous colonies can clog up water intake pipes. However,
as previously indicated, insect larvae and other organisms
may burrow into the gelatinous material, and it may have
some food value for them. I think it is possible that other
organisms may eat the colonies too - I believe a raccoon ate
a specimen I collected several years ago.
If you have any
additional questions, or observations, feel
free to get in touch. This is actually such an obscure
field, that I find it amazing that a number of people have
gotten in touch with me over the Internet!
Byron T. Backus
Subject: Pectinatella magnifica
Date: Fri, 15 Aug 1997 13:50:53 -0500 (EST)
From: Byron Backus <BACKUS.BYRON@epamail.epa.gov>
I am not aware
of any health hazard associated with
Pectinatella magnifica (other than the possibility of
someone slipping on a colony). I have handled colonies with
my bare hands, and have never had any signs of irritation.
If you take a colony and put it in a bucket, it will start
to smell after a few hours, and it may be that this is
indicative of some sort of bacterial decay process, but, as
far as I know, there is no potential for infection.
zooids that make up a P. magnifica colony are
filter feeders, so it is possible that the large number of
colonies are making a significant contribution to clearing
Most of the phylactolaemates
are either small and
inconspicuous organisms, or have a "mossy" appearance. P.
magnifica and Asajirella gelatinosa (formerly known as
Pectinatella gelatinosa) are capable of forming large
gelatinous colonies (sometimes, possibly under less than
optimum conditions, they form small colonies - about the
size of a fingernail). Asajirella gelatinosa is found in
Japan and other areas of Asia, although I am aware that it
has also been collected in Panama. I have worked with
budding statoblasts of Asajirella gelatinosa (the
statoblasts were sent to me by a Japanese scientist) and
obtained chromosome spreads. I was informed a few years ago
that Asajirella gelatinosa has been largely displaced from
Lake Tatara-numa (the source of his material) by
Pectinatella magnifica. Incidentally, P. magnifica and A.
gelatinosa are not that closely related - the massive
gelatinous growth form in both species is apparently an
example of convergent or independent evolution.
that you might look for (and I also observed
it in Massachusetts) is Cristatella mucedo. The colonies
are gelatinous, but considerably smaller than those of P.
magnifica. They tend to be elongate, perhaps 1-2 inches
long (but they can get longer - to 6 or 8 inches) and
perhaps 1/3 to 3/4 inch thick. They look like submerged
caterpillars. Usually, a number of colonies of C. mucedo
are found together in close proximity. The statoblast is
somewhat like that of P. magnifica, but with more spines,
and it tends to be somewhat smaller and more circular. The
statoblast of P. magnifica tends to have a saddle-shape when
seen in profile, while that of C. mucedo is flatter.
The person who
is probably the expert on Massachusetts
phylactolaemates is Doug Smith, at the University of
Massachusetts at Amherst, Dept. of Zoology. He has
collected a number of different species from the streams and
lakes of Massachusetts, and wrote a book a few years ago
describing the different species and the localities from which
he had collected them.
I will add here
that A. gelatinosa and a closely-related
species (to A. gelatinosa), Lophopodella carteri, have been
shown to contain a substance (or substances) which are toxic
to fish. This material is released when the colony is
damaged. If the colony is not damaged, then the fish and
phylactolaemate can co-exist. The toxin damages the gill
tissue, and is apparently not toxic to mammalian species.
However, I am not aware of any research along these lines
which has been conducted with P. magnifica. Incidentally,
Doug Smith has collected Lophopodella carteri in
Massachusetts (colonies tend to be greenish-gray in color,
about the size of a pea, and, when they are found, usually
are present in great numbers).
Byron T. Backus
Subject: Re: Pectinatella magnifica
Date: Mon, 29 Sep 1997 10:33:06 -0500 (EST)
To: Dick and Jill Miller <DMiller@gis.net>
I recently received
a query as to the composition of the
jelly-like substance of Pectinatella magnifica, and the
person indicated that this information was not on the
website, so here is the information that I have managed to
is from The Invertebrates, vol. 5, by L.H.
Hyman (1959): "The jelly of Pectinatella (Kraepelin, 1887)
consists of 99.7% water; the mass left by pressing out as
much water as possible was composed of 89.23% water, 0.88%
ash (salts), 6% protein, 1.25% chitin and 2.64% other
organic material. The presence of chitin was checked out by
crystallizing out glucosamine. Similar results were obtained
by Morse (1930), who also crystallized glucosamine; he found
that a mass of jelly weighing 1200 g when fresh dried to 5
The short article
by Withrow Morse on the composition of
Pectinatella magnifica appears in Science, in the issue of
March 7, 1930, p. 265 (Vol. LXXI), and includes the
secretion is not of the order of collagen
but of true protein... Protein reactions were typical of
such proteins as ovalbumin, serum albumin etc. The biuret
reaction was positive and typical, that is, like that of
white of egg and not like that of gelatin or peptone."
amino-acids were demonstrated: tyrosin,
tryptophane, cystin. In a cold extract of the dried material
all three were positive, but the reactions were intensifed
after acid hydrolysis. This was especially true of cystin.
The protein was heat coagulable."
"Of the inorganic
substances, sodium chloride was
demonstrable. Phosphorus was negative before hydrolysis, and
after boiling with equal volumes of sulphuric and nitric
acids, none was demonstrable. Calcium is present in copious
amounts, as one would suspect from the calcareous nature of
the body and statoblasts."
of these organisms is the supporting
structure composed of chitin. In the specimen, examined
chemically, glucosamine (galactosamine?) was readily
demonstrable after hydrolysis."
The only problem
I have with the above is the statement:
"...as one would suspect from the calcareous nature of the
body and statoblasts." I believe that Morse did not
actually analyze these, but relied on information from other