Method description search key Dutch freshwater bryozoans

Verder in Nederlands

  1. Search
  2. Site information

This page provides an overview of the method and definitions i developed for describing the Dutch freshwater bryozoans.
A complete list of definitions, a glossary, can be found here.

To describe freshwater bryozoans i use several 'aspect areas' with several well defined terms for each area. These are described below and have been worked out in the following aspect areas:

  1. Colony shape
  2. Branching pattern of the zooids
  3. Appearance of a polypid or the colony
  4. Polypid form
  5. Position of the polypid
  6. Number of tentacles per polypide
  7. Habitat
  8. Additional remarks

Area Term Description Examples Remarks
Colony shape Tree shaped Colony branches and is free standing or hanging and not gelatinous Tree shaped Tree shaped Tree shaped F. sultana
P. emarginata
P. fruticosa
Crawling Colony tubes follow the substrate
zooids not densly packed
Crawling Crawling P. casmiana
P. repens
P. fungosa
P. articulata
Hanging Colony has one point of attachment and is free hanging in the water (not tree-shaped) Hanging Hanging P. repens
C. mucedo
Encrusting Zooids densly packed and in one plane following the substrate
Also called fungoïde: "resembles a fungus", think of mouldy bread
Also compared to a lawn
Zooids densly packed"
Encrusting Encrusting P. fungosa
P. repens
P. magnifica
Knoll shaped Zooids densly packed and not in one plane
Colony has a three dimensional shape like a ball or a spindle
Knoll shaped P. magnifica Knoll shaped P. repens Knoll shaped P. fungosa P. magnifica
P. fungosa
soms P. repens
Caterpillar shaped The colony resembles a caterpillar
Also called band-shaped
A small colony is a circle
Caterpillar shaped - C. mucedo C. mucedo
Sack shaped The colony is sack shaped
Can be irregular, lobbed
Sack shaped - L. crystallinus L. crystallinus
Bushy Structure not well defined
Zooids grow in all directions and are entertwining
Only for non-gelatinous species
Bushy P. articulata
Branching pattern
of the zooids
- the way the colony branches (multiple approaches)
Regular Dichrotomous branching
Strictly regular branching, same way on each level
Regular branching Regular branching F. sultana
P. articulata
Irregular Antler shaped
Irregular branching pattern
on higer levels (further from point of adherence) smaller branches
onregelmatig vertakt P. repens
P. fungosa
Not branching The colony does not branch Not branching Not branching Not branching C. mucedo
P. magnifica
L. crystallinus
Open structure Structure of the zooid tubes easy to see open structure open structure open structure open structuur F. sultana
P. repens
P. fruticosa
P. emarginata
P. articulata
Closed structure Zoöids closely packed
structure of the zooid tubes not easy to see
Closed structure Closed structure P. fungosa
P. repens
Adhering tubes In combination with branching or crawling
Zooid tubes fuse (partially) when aligned
Adhering tubes P. emarginata
Non-adhering tubes In combination with branching or crawling
Zooid tubes never fuse; are always distincly separated
Non-adhering tubes Non-adhering tubes Non-adhering tubes F. sultana
P. fruticosa
Appearance of a polypid or the colony
- the way a zooid appears
Encrusted Zooid wall encrusted with sand, diatom shells and/or other material Covered F. sultana
Smooth Zooid wall smooth (not covered) Smooth P. articulata
C. mucedo
P. magnifica
Gelatinous Zooid part of a 'clump of yelly' Jelly like Jelly like P. magnifica
C. mucedo
L. crystallinus
Chitin shine Zooid wall has a chitin shine like beetles sometimes have
Never in combination with covered
Chitin shine P. articulata
Rimpled Zooid wall has clear rimples or rings around the zooid aperture Rings - H. punctata H. punctata
Spotted Zoöid wall has spots or splodges Spotted - H. punctata H. punctata
Transparent Zooid wall (almost) transparent Transparent H. punctata
P. magnifica
P. geimermassardi
Opaque Zooid wall cannot be seen through (and is not covered) Ondoorzichtig F. sultana
Sturdy Zooid impression is sturdy Sturdy F. sultana
P. emarginata
Brittle - slender Zooid seems brittle, fragile Brittle P. fruticosa
- of the polypide
Round Tentacle crown is (almost) round Round Round F. sultana
V. pavida
Horseshoe shaped Tentacle crown is horseshoe shaped
Also called U shaped
Horseshoe shaped Horseshoe shaped C. mucedo
P. fruticosa
P. magnifica
P. repens
Position of the polypid
- the way the polypide aperture is located in the zooid
Terminal At the end of a zooid tube / branch Terminal Terminal F. sultana
P. fruticosa
Sideways Sideways from one zooid
Not at the end of one zooid
Sideways P. articulata
Somewhere Multiple apertures from one tube (of fused zooids) Somewhere from the cystid tube P. repens
Anywhere Applicable to non-tube forming (gelatinous) colonies Somewhere from a colony Somewhere from a colony P. fungosa
C. mucedo
P. magnifica
Number of tentacles per polypide Low Fewer than 10 tentakels per polypide tentacle crown Tentakels per polypide laag V. pavida (8)
Average More than 10 and less than 50 tentacles per polypide tentacle crown Tentakels per polypide gemiddeld Tentakels per polypide gemiddeld F. sultana (16 - 30)
P. articulata (10 - 20)
P. casmiana (< 50)
P. emarginata (30 - 60)
P. fruticosa (30 - 60)
P. geimermassardi (30 - 40)
High more than 50 tentacles per polypide tentacle crown Tentakels per polypide hoog C. mucedo (80 - 100)
L. crystallinus (60 - 70)
P. magnifica (50 - 80)
H. punctata (40 - 70)
P. fungosa (< 70)
P. repens (40 - 70)
Habitat Fresh water Fresh standing or lightly flowing water - eutrophy does not matter Freshwater habitat Freshwater habitat C. mucedo
F. sultana
P. magnifica
Clean fresh water Fresh standing or lightly flowing water - low in pollution Clear fresh environment H. punctata
Brackish water Tastes salt, may vary in salinity Brackish habitat V. pavida
Additional remarks Important aspects not yet covered Example: usually on top of substrate Example: on top of substrate C. mucedo