Photo of the day (18): Pseudosuccinea columella

Pseudosuccinea columella is a freshwater snail from the family Lymnaeidae and it is native to Americas. It is also well known species in Europe as a “hothouse alien”. It is inadvertently spreading in aquaria and in ponds within greenhouses. Unfortunately it has been found also in the wild in Europe.

The shell of Pseudosuccinea columella resembles a shell of a Succinea land snail. The height of the shell of this specimen is 10.5 mm.


It can float on the water.


As all other Lymnaeidae it has its eyes at the base of its non-retractile tentacles.


And as all other Lymnaeidae it is exchanging gas trough a breathing pore (pneumostome). Pseudosuccinea columella can slide up its tube like pneumostome like this:


Another sequence:


Ventral view with pneumostome extended:



(in Polish) Jackiewicz M. 2000: Błotniarki Europy, Gastropoda, Pulmonata, Lymnaeidae.Wydawnictwo Kontekst, Poznań 116 pp., pages 28-29. ISBN 83-911532-4-0.

Pointier J. P., Coustau C., Rondelaud D. & Theron A. 2007. Pseudosuccinea columella (Say 1817) (Gastropoda, Lymnaeidae), snail host of Fasciola hepatica: First record for France in the wild. Parasitology Research 101(5): 1389–1392. doi:10.1007/s00436-007-0656-y


Photo of the day (14): Helisoma anceps

Helisoma anceps, synonym: Planorbella anceps, is a freshwater snail from family Planorbidae. It is native to North America. It is sometimes kept in aquaria in Europe.

Planorbidae are breathing free air and their breathing pore is called pneumostome (it is the same as in land snails). The pneumostome is on the right side of the body, but it is close to the median line (= to the center).

The very large pneumostome is visible on this photo of juvenile Helisoma anceps:


Additionally Planorbidae have another breathing organ, that is used for breathing underwater. It is called pseudobranch and it is placed on the left side of the body. It evolved by extending of the anal region and therefore anus is always close to the pseudobranch. The pad-like pseudobranch of an adult Helisoma anceps is about 2 mm wide and 1 mm high. You can see the pseudobranch easily, if you will watch to the left side of your planorbid snails crawling in the water.

The following two photos shows the extended pseudobranch of the same specimen of juvenile Helisoma anceps:



Baker F. C. 1945: The molluscan family Planorbidae. The University of Illinois Press, Urbana. page 3 and page 126. Plate 23, figure 4.