Byron Backus on Bryozoa

Subject: Pectinatella magnifica
    Date: Thu, 14 Aug 1997 18:54:12 -0500 (EST)
   From: BACKUS.BYRON@epamail.epa.gov
       To: DMiller@ziplink.net

          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
          days).

          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).

          The statoblasts 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.

          Pectinatella 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
          703-305-7043(W)
          301-984-9164(H)
 

Subject: Pectinatella magnifica
   Date:  Fri, 15 Aug 1997 13:50:53 -0500 (EST)
   From: Byron Backus <BACKUS.BYRON@epamail.epa.gov>
     To:   DMiller@ziplink.net

          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.

          The individual 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
          the water.

          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.

          Another species 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
          703-305-7043(W)
          301-984-9164(H)

 
Subject: Re[2]: Pectinatella magnifica
    Date: Mon, 29 Sep 1997 10:33:06 -0500 (EST)
   From: BACKUS.BYRON@epamail.epa.gov
       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
          obtain:

          The following 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
          g."

          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
          following:

          "...the jelly-like 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."

          "The following 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."

          "Characteristic 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
          sources.

          -Byron