Lophopus crystallinus (Pallas 1768)

Verder in Nederlands

  1. More information
  2. Photos
  3. Microscope photos and videos
  4. Statoblasts

Proposal for common name: Sackformed bryozoan or moss animal

Lophopus crystallinus


Class Family Genus Species First described by
Phylactolaemata Lophopodiae Lophopus L. crystallinus Pallas 1768


The following synonyms have been used to indicate Lophopus crystallinus:

  1. Tubularia crystallina (Pallas 1768)
  2. Lophopus trembleyi (Jullien 1885)
  3. Lophopus crystallinus (Abrikosov 1925)


Also see the generic class and genus description in the classification page.
A combination of literature has been used to create this description.

  1. Jelly like body stiff and fully translucent
  2. If at all encrusted in the base part
  3. The cystid is reduced to the mouth cone
  4. The large polypids extend significantly from the jelly formed body
  5. Colonies are sack - fan shaped
  6. Colonies never branch
  7. Colonies are sometimes lobed by extensions at the surface
  8. The lophofores are oriented in one direction and extend at one side of the sack-like colony
  9. 10 to 20 zooids form one colony
Color Light colored; color depends soley on polyp gut contents;
often yellow-green
Tentacle crown Horseshoe shaped tentacle crown with 60 to 70 tentacles.
Size One zooid is about 2 mm long
A colony 4 cm maximum
Statoblasts Statoblasts in floating form (floatoblasts) spool shaped with sharp (blunt?) points at the poles
Statoblasts in sinking form (sessoblasts) more asymmetrical oval
Each polipide has one statoblast
Conditions Often on aquatic plants in cool waters
Distribution No information found in literature
Additional Rare

Relevant literature

To be completed

  1. [Mundy] - A key to the British and European Freshwater Bryozoans
  2. [Wood II] - A new key to the freshwater bryozoans of Britain, Ireland and Continental Europe

My observations

  1. The only location I found Lophopus was at 12 m depth at 12 oC in a fairly eutrophic environment (sight depth about 50 cm)
  2. More shallow, above 7 meter, it was warmer and en less eutrophic (5 m sight depth) and no Lophopus could be found
  3. There were hundreds of colonies, many of which were splitting up or showed signs of recently having done so
  4. Given the slime trails, it was clear that many colonies had actively moved. Often several times their own size
  5. Inside some colonies could be seen how new zooids were forming in the sack formed colony base.
  6. The surface of the - jelly like - sack has a noticeable shine. This is unlike any other freshwater bryozoan.
  7. Also it is immediately apparent that all zooids extend on one side of the colony sack. From what I saw typically the zooids extend in the direction the colony is crawling.
    The literature gives as explanation that young zooids grow on top of older zooids making them all extend in the same direction.
    This photo shows the relation between crawling direction and zooid direction.
  8. Under a microscope Lophopus is irritating. Every time a nice image has been found, the colony crawls a bit changing the image.
    The crawling itself can be easily seen with a little patience. Clear movements of some areas of the colony sack can be seen within 1 minute.
  9. Lophopus crystallinus was growing on wood and not on aquatic plants in this location. At the depth the colonies were living no aquatic plants were available as it was too dark and probably too cold. Lophopus seemed to avoid metal parts of the boat it was living on.
  10. The differences in colony size were also significant; ranging from a few zooids to 30 or 40.
  11. The sack formed part of the colony is certainly clear but not really stiff. It has a flexible quality like an amoeba.
  12. Observations by Silvia Waajen and Jan Vossen in the same location in wintertime shows that Lophopus crystallinus moves to shallower waters as temperature drops and will grow on aquatic plants and on rock