Tim Wood on Bryozoa

Subject: Pectinatella magnifica
    Date: Fri, 15 Aug 1997 09:33:45 -0500 (EST)
   From: TWOOD@desire.wright.edu
       To: dmiller@ziplink.net

Hello, Dick! Thanks for your inquiry about Pectinatella. I also read your
very interesting account on the web. Welcome to bryozoans!!

The 70-page book you mentioned deals with Ohio bryozoans in general with a
small section on Pectinatella. Unfortunately, it not in electronic format,
although I could mail you a copy along with other papers and articles about
the species. It may depend on how much detail you'd like about life history,
ecology, genetics, histology, etc.

Pectinatella magnifica is a true North American species, first reported from
Massachusetts in 1866. Current records for the state are maintained by Doug
Smith, Zoology Department, 348 Morrill Science Center, University of Massachu-
setts, Amherst, MA  01003-5810.  Tel. (413) 545-1956. Email: dgsmith@bio.umass.
edu.  PMAG (as we call it here) was reported from eastern Texas in the early
1980's, has crossed the Pacific to Japan and recently invaded Korea. In Japan
the colonies are described as reaching the size of a large sheep.

Bryozoans in general, and PMAG in particular, removed large quantities of
suspended material from the water, including both suspended algae and
inorganic clay/silt. If colonies are abundant in the lake this year they
could well be responsible for at least some of the water transparency.

Pectinatella populations rise and fall. A large number of colonies this year
does not mean you will see them at all next year. Statoblasts do not survive
freezing very well. Normally they attach to free clumps of algae or other
debris which then sinks to the bottom in the fall. The following spring as
that material decays the statoblasts are released to bob back to the surface
and germinate. (At least that's the current overwintering theory). An early
summer generation produces quantities of "larvae," which are actually little
ciliated colonies looking a lot like miniature blimps. These are free-swimming
for 2-24 hours, then settle on a suitable substrate and establish new colonies
for a late summer statoblast-producing generation.

Most freshwater bryozoan grow directly on submerged surfaces, which can soon
become crowded with attached animals. Pectinatella makes its own substrate
with that massive gelatinous core so enormous numbers of zooids can lodge
on small twigs. The slimy surface with its distinctive odor is thought to
repel potential predators, although very little is actually known about that
aspect.

All the best,
Tim
Dr. Timothy S. Wood
Department of Biological Sciences
Wright State University
Dayton, OH  45435
Tel: (937) 775-2542; Fax: (937) 775-3320
Email: twood@wright.edu